Patent Publication Number: US-2013245399-A1

Title: Apparatus and method for measuring skin moisture

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 2012-0026808 filed on Mar. 15, 2012, the entire disclosures of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present disclosure relates to an apparatus and a method for measuring moisture of a testee&#39;s skin, and particularly relates to a skin moisture measuring apparatus capable of providing measurement information of moisture of a testee&#39;s skin by using smart devices and a skin moisture measuring method using the same. 
     BACKGROUND OF THE INVENTION 
     A smart device is a mobile terminal device that is not limited in function and can be modified or extended in function by using an application program (generally, referred to as “application” or “app”). By way of example, the smart device may include a smart phone, a smart TV, a smart key, a smart card, and a tablet computer (or a smart pad). 
     By way of example, a smart phone combines a mobile phone (cellular phone) and a personal digital assistant (PDA) and is designed for scheduling, sending and receiving faxes, and data communication such as internet communication in addition to functions of a mobile phone. Particularly, unlike a conventional mobile phone sold and used as a complete product, the smart phone has functions which can be extended in various ways by additionally installing, executing and deleting various applications as well as functions of a mobile phone. 
     Typically, such a smart device performs a data processing with respect to external devices through wired/wireless data communication such as a USB and Bluetooth. In order to do so, the smart device requires a communication interface port for connection with the external devices and needs to use a complicated communication protocol. Further, the external devices require their own power supply sources. 
     Therefore, there is a need to connect a smart device with various external devices, perform a data processing, and supply power to the external devices in a more simple way. 
     In this regard, Korean Patent No. 10-0819270 (entitled “Earmicrophone apparatus for supplying power to a mobile terminal and the mobile terminal”) describes mobile terminal that includes a first conventional plug connected to an earset device and a second plug for supplying power to the earset device. 
     Meanwhile, skin is the soft outer covering of vertebrates and has functions such as protection, thermoregulation, excretion, respiration, and the like. It has been known that such functions of the skin are influenced by a skin condition, particularly a skin moisture content. 
     A lot of devices for measuring skin moisture have been disclosed. 
     By way of example, Korean Patent No. 10-0938403 (entitled “Device for measuring moisture on skin”) describes a skin moisture measuring apparatus that calculates a primary skin moisture content through skin moisture measurement and moisture measurement by using bioimpedance and then calculating a final skin moisture content by amending the primary skin moisture content with variables such as a temperature and humidity of the external environment. 
     Further, Korean Patent No. 10-0979886 (entitled “Sensor with multi skin checking means”) describes a skin condition measuring sensor capable of measuring skin moisture and skin elasticity at a time. 
     However, a conventional skin moisture measuring apparatus uses a personal computer or a separate device for measurement value analysis and input/output interface with a user, and, thus, the user requires a personal computer or a separate device including a program related to skin moisture measurement and needs to know how to use the device. Therefore, the conventional skin moisture measuring apparatus offers low transportability and convenience. 
     BRIEF SUMMARY OF THE INVENTION 
     In view of the foregoing, illustrative embodiments of the present disclosure provide a skin moisture measuring method and a skin moisture measuring apparatus with high convenience and transportability that is easily connected to a smart device via an earphone port of the smart device and offers a measurement result of a moisture content in a testee&#39;s skin through the smart device. 
     In accordance with one aspect of an illustrative embodiment, there is provided a skin moisture measuring apparatus that measures moisture in a testee&#39;s skin. The skin moisture measuring apparatus includes an earphone plug that is connected to an earphone port of a smart device and connects the skin moisture measuring apparatus to the smart device; an oscillation signal generation unit that generates an oscillation signal; and a sensor unit that includes two or more contact portions exposed to the outside to be in direct with the testee&#39;s skin, modifies the oscillation signal depending on an electrical resistance corresponding to a moisture content in the testee&#39;s skin and formed between the two or more contact portions, and generates a measurement signal. In the skin moisture measuring apparatus, the sensor unit transmits the measurement signal to the smart device through the earphone plug. 
     If the smart device receives the measurement signal, the smart device may draw skin moisture information corresponding to the received measurement signal and display the skin moisture information. 
     Further, in accordance with another aspect of the illustrative embodiment, there is provided a skin moisture measuring method that measures moisture in a testee&#39;s skin by using a skin moisture measuring apparatus to be connected to a smart device through an earphone port of the smart device. The skin moisture measuring method includes generating an oscillation signal based on power supplied to the skin moisture measuring apparatus; and generating a measurement signal by modifying the oscillation signal depending on a moisture content in the testee&#39;s skin. 
     In accordance with the present disclosure, the skin moisture measuring apparatus can be easily connected to the smart device via the earphone port of the smart device. Further, the skin moisture measuring apparatus connected to the smart device measures the moisture content contained in the testee&#39;s skin and displays the measurement result through the smart device. Therefore, the skin moisture measuring apparatus in accordance with the present disclosure can offer improved transportability and convenience as compared with a case where skin moisture measurement is carried out by a personal computer or a separate device with low mobility. 
     Herein, the skin moisture measuring apparatus is supplied with power from the smart device and does not require an additional power supply source. Therefore, a size and a weight of the skin moisture measuring apparatus can be reduced, and, thus, transportability can be further improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments will be described in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are, therefore, not to be intended to limit its scope, the disclosure will be described with specificity and detail through use of the accompanying drawings, in which: 
         FIG. 1  is a block diagram illustrating a skin moisture measuring system in accordance with an illustrative embodiment; 
         FIG. 2  is a block diagram illustrating an input/output port of  FIG. 1 ; 
         FIG. 3  a block diagram illustrating a smart device of  FIG. 1 ; 
         FIG. 4  is a block diagram illustrating a skin moisture measuring apparatus of  FIG. 1 ; 
         FIG. 5  provides an example of the skin moisture measuring apparatus of  FIG. 4 ; 
         FIG. 6  provides an example of the skin moisture measuring system of  FIG. 1 ; 
         FIG. 7  is a flow chart illustrating a skin moisture measuring method using a smart device in accordance with an illustrative embodiment; 
         FIG. 8  is a flow chart illustrating a step of executing a skin moisture measurement application of  FIG. 7 ; and 
         FIG. 9  is a flow chart illustrating a process of transmitting a measurement signal of  FIG. 8  by using a skin moisture measuring apparatus in accordance with an illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, examples of the present disclosure will be described in detail with reference to the accompanying drawings so that the present disclosure may be readily implemented by those skilled in the art. However, it is to be noted that the present disclosure is not limited to the embodiments but can be embodied in various other ways. In drawings, parts irrelevant to the description are omitted for the simplicity of explanation, and like reference numerals denote like parts through the whole document. 
     Through the whole document, the term “connected to” or “coupled to” that is used to designate a connection or coupling of one element to another element includes both a case that an element is “directly connected or coupled to” another element and a case that an element is “electronically connected or coupled to” another element via still another element. Further, the term “comprises or includes” and/or “comprising or including” used in the document means that one or more other components, steps, operation and/or existence or addition of elements are not excluded in addition to the described components, steps, operation and/or elements unless context dictates otherwise. 
     Hereinafter, a skin moisture measuring system in accordance with an illustrative embodiment will be explained in detail with reference to  FIG. 1 .  FIG. 1  is a block diagram illustrating a skin moisture measuring system in accordance with an illustrative embodiment. 
     As depicted in  FIG. 1 , a skin moisture measuring system  100  in accordance with an illustrative embodiment includes a smart device  10  and a skin moisture measuring apparatus  20 . 
     The smart device  10  is a mobile terminal that has preset functions and can be modified or extended in function by additionally installing, executing, and deleting an application program. 
     The smart device  10  includes at least one input/output port  11  for performing a data processing and supplying power to external devices. 
     The input/output port  11  is connected to any one earphone plug of multiple external devices which can be connected to the smart device  10 . Herein, the multiple external devices may include a data processing device, such as a printer, a keyboard, a joy stick, and a sensor, configured to be connected to the smart device  10  and perform data communication for executing various applications. 
     Typically, the smart device  10  includes an earphone port to be connected to a sound system including a speaker or an earphone that converts an electric signal to a sound for listening to music and movies, a microphone that converts a sound to an electric signal for recording, and an earset (earphone-microphone set) that combines an earphone with a microphone for hands-free phone call. Herein, the earphone port may be a socket of a cylindrical connector. 
     The skin moisture measuring apparatus  20  in accordance with an illustrative embodiment is connected to the smart device  10  via the earphone port among the multiple input/output ports  11  provided in the smart device  10 . Thus, the smart device  10  does not require a separate input/output port for connection between the smart device  10  and the skin moisture measuring apparatus  20 . 
     The smart device  10  and the input/output port  11  included therein will be explained in more detail with reference to  FIGS. 2 and 3 . 
     The skin moisture measuring apparatus  20  is connected to the smart device  10  via the input/output port  11  and driven by the smart device  10 . 
     That is, when the smart device  10  is connected to the skin moisture measuring apparatus  20  via the input/output port  11 , the smart device  10  supplies power to the skin moisture measuring apparatus  20 . If the skin moisture measuring apparatus  20  is in contact with a testee&#39;s skin selected by a user while being supplied with power from the smart device  10 , the skin moisture measuring apparatus  20  transmits a measurement signal corresponding to a moisture content in the testee&#39;s skin to the smart device  10 . When the smart device  10  receives the measurement signal from the skin moisture measuring apparatus  20 , the smart device  10  draws skin moisture information corresponding to the received measurement signal and displays the drawn skin moisture information for the user to see. 
     The skin moisture measuring apparatus  20  includes an input/output plug  21  connected to the input/output port  11  in order to be connected to the smart device  10 . Herein, the input/output plug  21  may be an earphone plug matched with the earphone port  11 . By way of example, the earphone plug  21  may be a cylindrical plug which can be connected to the earphone port  11 . 
     Hereinafter, the smart deice  10  of  FIG. 1  will be explained in more detail with reference to  FIGS. 2 and 3 .  FIG. 2  is a block diagram illustrating an input/output port of  FIG. 1  and  FIG. 3  a block diagram illustrating a smart device of  FIG. 1 . 
     As depicted in  FIG. 2 , the input/output port  11  of the smart device  10  may be an earphone port including a ground terminal  11   a,  a microphone terminal  11   b,  and first and second speaker terminals  11   c  and  11   d.    
     By way of example, if an earphone plug of an earset (not illustrated) among the multiple external devices is connected to the earphone port  11 , a connection signal of the earset may be input to the microphone terminal  11   b  and an audio signal collected by a microphone (not illustrated) of the earset may be input to the microphone terminal  11   b.  The first and second speaker terminals  11   c  and  11   d  respectively output audio signals to both earphones (not illustrated) of the earset. In this case, an input terminal of the earphone plug of the earset is connected to the microphone terminal  11   b  and an output terminal thereof is connected to the first and second speaker terminals  11   c  and  11   d.    
     If the earphone plug of the earset includes a ground terminal, the ground terminal of the earphone port of the smart device is connected to the ground terminal of the earphone plug of the earset, and, thus, the earset can be supplied with a ground voltage. 
     Further, at least one of the microphone terminal  11   b  and the first and second speaker terminals  11   c  and  11   d  may be used to supply power to the multiple external devices including the earset. That is, only one of the microphone terminal  11   b  and the first and second speaker terminals  11   c  and  11   d  may be used to supply power. Otherwise, all of the microphone terminal  11   b  and the first and second speaker terminals  11   c  and  11   d  may be used to supply power. The ground terminal  11   a  connected to the ground terminal of the earphone plug may be used to supply a ground voltage. 
     By way of example, if the earphone plug of the skin moisture measuring apparatus  20  is connected to the earphone port  11 , power may be supplied to the skin moisture measuring apparatus  20  through the microphone terminal  11   b  of the earphone port. Otherwise, power may be supplied to the skin moisture measuring apparatus  20  through any one of the first and second speaker terminals  11   c  and  11   d  of the earphone port  11 . 
     The microphone terminal  11   b  of the earphone port may receive a measurement signal from the skin moisture measuring apparatus  20 . In this case, the measurement signal has a frequency selected from an audio sampling rate range of the smart device  10  in order to use the existing microphone terminal  11   b.  By way of example, the audio sampling rate range of the smart device  10  may be from about 0 Hz to about 22.05 kHz, particularly from about 30 Hz to about 22.05 kHz. 
     If the earphone plug  21  of the skin moisture measuring apparatus  20  includes a ground terminal, the ground terminal  11   a  of the earphone port is connected to the ground terminal of the earphone plug  21  so as to be used to supply a ground voltage to the skin moisture measuring apparatus  20 . 
     As depicted in  FIG. 3 , the smart device  10  includes the input/output port  11 , a connected device sensing unit  12 , a signal process control unit  13 , an application management unit  14 , a power supply unit  15 , a data analysis unit  16 , skin moisture information management unit  17 , and a display unit  18 . 
     As described above, the input/output port  11  is an earphone port that is connected to an earphone plug of the external device and connects the smart device  10  to the external device. 
     If any one of input/output plugs of the multiple external devices is connected to the input/output port  11 , the connected device sensing unit  12  receives a connection signal from the external device connected to the input/output port  11 . Then, based on the received connection signal, the connected device sensing unit  12  senses the external device connected to the input/output port  11  and transmits information about the sensed external device to the signal process control unit  13 . 
     Herein, the connection signal may be generated when the earphone plug of the external device is connected to the earphone port  11 . By way of example, the connection signal may correspond to an initial power value of the external device or a voltage discharged to supply power to the external device. 
     Although not illustrated in detail in  FIG. 3 , the smart device may further include an external device management unit that contains a reference connection signal corresponding to various external devices. In this case, based on the reference connection signal corresponding to various external devices, the connected device sensing unit can find an external device to be matched with the received connection signal. 
     The signal process control unit  13  receives the information about the sensed external device from the connected device sensing unit  12  and executes a signal process application corresponding to the sensed external device. 
     Herein, the signal process application include an algorithm including supplying power to the external device, transmitting and receiving data to/from the external device, analyzing a signal received from the external device by a predetermined method, and outputting an analysis result. 
     In particular, if the connected device sensing unit  12  senses the skin moisture measuring apparatus  20  connected to the earphone port  11 , the signal process control unit  13  executes a skin moisture measurement application. 
     Herein, the skin moisture measurement application includes an algorithm including supplying power to the skin moisture measuring apparatus  20 , controlling the skin moisture measuring apparatus  20 , and displaying a moisture content in a testee&#39;s skin based on a measurement signal received from the skin moisture measuring apparatus  20 . 
     The application management unit  14  contains one or more signal process applications to be matched with various external devices which can be connected to the smart device as well as the skin moisture measurement application. 
     Then, the signal process control unit  13  searches at least one application corresponding to the sensed external device from various signal process applications contained in the application management unit  14  and is supplied with the at least one searched signal process application from the application management unit  14 . 
     The power supply unit  15  supplies power to the connected external device through the earphone port  11  based on the signal process application executed by the signal process control unit  13 . That is, the power supply unit  15  supplies power to the skin moisture measuring apparatus  20  through the earphone port  11  based on the skin moisture measurement application executed by the signal process control unit  13 . 
     By way of example, the power supply unit  15  outputs a high-level signal continuously or periodically to any one of the microphone terminal  11   b  and the first and second speaker terminals  11   c  and  11   d  of the earphone port  11 , so that the power supply unit  15  can supply power to the skin moisture measuring apparatus  20 . If the power supply unit  15  outputs a high-level signal continuously or periodically to any one of the microphone terminal  11   b  and the first and second speaker terminals  11   c  and  11   d  of the earphone port  11 , the skin moisture measuring apparatus  20  may include a rectifier circuit that converts a periodic high-level signal to power. 
     By way of example, the power supply unit  15  outputs a high-level signal to the microphone terminal  11   b  of the earphone port, so that the power supply unit  15  can supply power to the skin moisture measuring apparatus  20 . 
     The data analysis unit  16  analyzes a data signal of the external device received through the input/output port in a predetermined method based on the signal process application executed by the signal process control unit  13  and allows an analysis result to be displayed on the display unit  18 . 
     By way of example, the data analysis unit  16  receives the measurement signal from the skin moisture measuring apparatus  20  through the earphone port  11  based on the signal process application executed by the signal process control unit  13  and draws skin moisture information corresponding to the received measurement signal. Then, the skin moisture information is transmitted to the signal process control unit  13  so as to be displayed on the display unit  18 . 
     The skin moisture information management unit  17  contains skin moisture information matched with each measurement signal. 
     The data analysis unit  16  searches skin moisture information matched with the received measurement signal from the skin moisture information contained in the skin moisture information management unit  17 . 
     The display unit  18  displays a video signal or an audio signal based on the signal process application executed by the signal process control unit  13 . By way of example, the display unit  18  may display the skin moisture information drawn by the data analysis unit  16  on a screen based on the skin moisture measurement application. 
     Hereinafter, the skin moisture measuring apparatus  20  of  FIG. 1  will be explained in more detail with reference to  FIGS. 4 and 5 .  FIG. 4  is a block diagram illustrating a skin moisture measuring apparatus of  FIG. 1  and  FIG. 5  provides an example of the skin moisture measuring apparatus of  FIG. 4 . 
     As depicted in  FIG. 4 , the skin moisture measuring apparatus  20  includes the earphone plug  21 , a power supply unit  22 , an oscillation signal generation unit  23 , and a sensor unit  24 . 
     The earphone plug  21  connected to the earphone port  11  of the smart device  10  connects the smart device  10  to the skin moisture measuring apparatus  20 . 
     The power supply unit  22  applies a driving signal to the oscillation signal generation unit  23  based on power supplied from the outside of the skin moisture measuring apparatus  20 . In particular, the power supply unit  22  may be supplied with power from the smart device connected to the earphone plug  21 . 
     The sensor unit  24  includes two or more contact portions (not illustrated) exposed to the outside of a housing such that the sensor unit  24  can be in direct contact with the testee&#39;s skin. The sensor unit  24  generates a measurement signal corresponding to a moisture content in the testee&#39;s skin. 
     As depicted in  FIG. 5 , the earphone plug  21  includes an input terminal  21   a  connected to any one of the microphone terminal  11   b  and the first and second speaker terminals  11   c  and  11   d  of the earphone port to be supplied with power and an output terminal  21   b  connected to the microphone terminal  11   b  of the earphone port  11  to output a measurement signal. 
     Herein, the input terminal  21   a  is not only used to be supplied with power but also used to receive a control signal of the smart device  10  about the skin moisture measuring apparatus  20 . 
     Further, the earphone plug  21  may further include a ground terminal  21   c  connected to the ground terminal  11   a  of the earphone port  11  to be supplied with a ground voltage. 
     The power supply unit  22  applies a driving signal to the oscillation signal generation unit  23  based on the power supplied from the smart device  10 . 
     By way of example, the power supply unit  22  may be a capacitor connected between the input terminal  21   a  and the ground terminal  21   c.  The power supply unit  22  is charged with the power supplied from the smart device  10  through the input terminal  21   a  and discharged by the oscillation signal generation unit  23 . 
     The oscillation signal generation unit  23  generates an oscillation signal by oscillating a driving signal applied from the power supply unit  22  to have a certain frequency. The oscillation signal generation unit  23  positively feeds back a part of an output signal amplified from the driving signal, so that the oscillation signal generation unit  23  may serve as an oscillation circuit that generates oscillation. 
     Herein, a frequency of the oscillation signal is selected from the audio sampling rate range of the smart device  10 . By way of example, the audio sampling rate range of the smart device  10  may be from about 0 Hz to about 22.05 kHz, particularly from about 30 Hz to about 22.05 kHz in order to use the existing microphone terminal  11   b  for receiving an audio signal from the microphone when a measurement signal converted from the oscillation signal is input. If the generated oscillation signal has a frequency in the audio sampling rate range, the measurement signal also has a frequency in the audio sampling rate range, and, thus, it can be input to the smart device  10  through the existing microphone terminal  11   b.    
     The sensor unit  24  includes two or more contact portions  24   a  and  24   b  which can be in contact with the testee&#39;s skin. Further, the sensor unit  24  modifies an oscillation signal depending on a moisture content in the testee&#39;s skin and generates a measurement signal. 
     Before the two or more contact portions  24   a  and  24   b  are in contact with the testee&#39;s skin, an electrical resistance sk between the contact portions  24   a  and  24   b  is maintained in a predetermined range by air or a separate dielectric member and does not correspond to a moisture content in the testee&#39;s skin. Therefore, a measurement signal is generated from an oscillation signal modified depending on the electrical resistance sk in the predetermined range between the contact portions  24   a  and  24   b  and can be analyzed as an initial value that does not correspond to the moisture content. 
     If the two or more contact portions  24   a  and  24   b  are in contact with the testee&#39;s skin, the electrical resistance sk corresponding to the moisture content in the testee&#39;s skin and formed between the contact portions  24   a  and  24   b  is modified so as to be out of the predetermined range. 
     That is, the electrical resistance sk between the contact portions  24   a  and  24   b  is modified in a range corresponding to the moisture content in the testee&#39;s skin and a variance in oscillation signal for generating a measurement signal is modified accordingly. By way of example, a variance in amplitude of the oscillation signal may be modified depending on the electrical resistance sk between the contact portions  24   a  and  24   b.    
     Therefore, a measurement signal is generated from an oscillation signal modified depending on the electrical resistance sk corresponding to the moisture content in the testee&#39;s skin and formed between the contact portions  24   a  and  24   b  between the contact portions  24   a  and  24   b  and can be analyzed as a measurement value corresponding to the moisture content in the testee&#39;s skin. That is, a variance in oscillation signal is sensed from a difference between the measurement signal and the oscillation signal and the electrical resistance sk between the contact portions  24   a  and  24   b  is drawn, and based on the electrical resistance sk, the moisture content in the testee&#39;s skin is calculated. 
     The generated measurement signal is transmitted to the smart device  10  through the output terminal  21   b  of the earphone plug connected to the microphone terminal  11   b  of the earphone port. 
     The smart device  10  in accordance with the illustrative embodiment may include any mobile terminal in which a skin moisture measurement application can be installed. 
     In particular, as depicted in  FIG. 6 , in the skin moisture measuring system  100 , the smart device  10  may be a smart phone. Further, the skin moisture measuring apparatus  20  may be a small-sized device including the earphone plug to be connected to the earphone port  11  of the smart device  10  and the two or more contact portions  24   a  and  24   b  exposed to the outside of the housing in order to offer transportability and convenience. 
     Hereinafter, a skin moisture measuring method in accordance with an illustrative embodiment will be explained with reference to  FIGS. 7 to 9 . 
       FIG. 7  is a flow chart illustrating a skin moisture measuring method using a smart device in accordance with an illustrative embodiment and  FIG. 8  is a flow chart illustrating a step of executing a skin moisture measurement application of  FIG. 7 .  FIG. 9  is a flow chart illustrating a process of transmitting a measurement signal of  FIG. 8  by using a skin moisture measuring apparatus in accordance with an illustrative embodiment. 
     As depicted in  FIG. 7 , a skin moisture measuring method using the smart device  10  which can be connected to a skin moisture measuring apparatus through an input/output port includes a step (S 110 ) of receiving a connection signal from an external device connected to the input/output port, a step (S 120 ) of determining whether or not the received connection signal corresponds to the skin moisture measuring apparatus, and a step (S 130 ) of executing a skin moisture measurement application if the received connection signal corresponds to the skin moisture measuring apparatus. If the received connection signal does not correspond to the skin moisture measuring apparatus, the method further includes a step (S 140 ) of searching a signal process application corresponding to another external device and executing the searched signal process application. 
     As depicted in  FIG. 8 , the step (S 130 ) of executing a skin moisture measurement application includes a step (S 131 ) of supplying power to the skin moisture measuring apparatus, a step (S 132 ) of receiving a measurement signal corresponding to a moisture content in a testee&#39;s skin from the skin moisture measuring apparatus, a step (S 133 ) of drawing skin moisture information corresponding to the received measurement signal, and a step (S 134 ) of displaying the skin moisture information. 
     As depicted in  FIG. 9 , a step of generating a measurement signal using the skin moisture measuring apparatus  20  includes a step (S 210 ) of generating an oscillation signal based on supplied power and a step (S 220 ) of modifying the oscillation signal depending on a moisture content in a testee&#39;s skin, generating a measurement signal, and transmitting the generated measurement signal. The oscillation signal can be generated based on power supplied from the smart device  10  (S 210 ). 
     The above-described skin moisture measuring method will be explained in detail as follows. 
     The earphone port  11  of the smart device  10  is connected to the earphone plug  21  of the skin moisture measuring apparatus  20 , so that the smart device  10  is connected to the skin moisture measuring apparatus  20 . In this case, the skin moisture measuring apparatus  20  connected to the smart device  10  through the earphone port  11  transmits a connection signal to the smart device  10 . 
     The smart device receives the connection signal (S 110 ) and searches an external device corresponding to the received connection signal from multiple external devices which can be connected to the earphone port  11 . At the same time, the smart device  10  determines whether or not the received connection signal corresponds to the skin moisture measuring apparatus  20  (S 120 ). 
     If the received connection signal does not correspond to the skin moisture measuring apparatus  20 , the smart device  10  executes a signal process application matched with the searched external device (S 140 ). 
     That is, the smart device  10  re-searches another external device corresponding to the received connection signal from the other external devices except the skin moisture measuring apparatus  20  and executes the matched signal process application. Meanwhile, if the received connection signal corresponds to the skin moisture measuring apparatus  20 , a skin moisture measurement application matched with the skin moisture measuring apparatus  20  is executed (S 130 ). 
     The smart device  10  supplies power to the skin moisture measuring apparatus  20  connected to the earphone port  11  based on the executed skin moisture measurement application (S 131 ). At the same time, the smart device  10  waits for a measurement signal of the skin moisture measuring apparatus  20 . 
     The skin moisture measuring apparatus  20  is supplied with power from the smart device  10  and generates an oscillation signal based on the supplied power (S 210 ). 
     Then, the skin moisture measuring apparatus  20  modifies the oscillation signal depending on an electrical resistance between two or more contact portions in contact with a testee&#39;s skin, generates a measurement signal, and transmits the generated measurement signal to the smart device  10  (S 220 ). 
     Herein, the electrical resistance between two or more contact portions corresponds to a moisture content in the testee&#39;s skin, and, thus, a variance in oscillation signal, i.e. the measurement signal, represents a measurement value corresponding to the moisture content in the testee&#39;s skin. 
     If the smart device  10  receives the measurement signal from the skin moisture measuring apparatus  20  while executing the skin moisture measurement application, skin moisture information corresponding to the measurement signal is drawn (S 133 ) and the skin moisture information is provided to a user (S 134 ). 
     As described above, the skin moisture measuring system and the skin moisture measuring method using the system use the smart device  10  and the skin moisture measuring apparatus  20  to be connected to the earphone port  11  of the smart device  10 , and, thus, transportability and convenience can be improved. 
     Herein, the skin moisture measuring apparatus is driven after being supplied with power from the smart device  10  through the earphone port  11 . Thus, the skin moisture measuring apparatus does not require an additional battery or power supply unit. Therefore, a size and a weight of the skin moisture measuring apparatus  20  can be reduced, and, thus, transportability can be further improved. 
     The smart device  10  senses connection with the skin moisture measuring apparatus  20  based on a characteristic connection signal of the skin moisture measuring apparatus  20  and executes a signal process application matched with the connected skin moisture measuring apparatus  20 . Thus, a skin moisture measurement application is executed just by connecting the skin moisture measuring apparatus  20  to the smart device  10 . Therefore, inconvenience of the user can be reduced. 
     Further, if the user is skilled in using the smart device  10 , the user can measure a moisture content in the testee&#39;s skin by using the skin moisture measuring apparatus without any training. Therefore, convenience can be further improved. 
     For reference, each of components illustrated in  FIGS. 1 to 4  in accordance with the illustrative embodiment of the present disclosure may imply software or hardware such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC), and they carry out a predetermined function. 
     However, the components are not limited to the software or the hardware, and each of the components may be stored in an addressable storage medium or may be configured to implement one or more processors. 
     Accordingly, the components may include, for example, software, object-oriented software, classes, tasks, processes, functions, attributes, procedures, sub-routines, segments of program codes, drivers, firmware, micro codes, circuits, data, database, data structures, tables, arrays, variables and the like. 
     The components and functions thereof can be combined with each other or can be divided. 
     The illustrative embodiments can be embodied in a storage medium including instruction codes executable by a computer or processor such as a program module executed by the computer or processor. A data structure in accordance with the illustrative embodiments can be stored in the storage medium executable by the computer or processor. A computer readable medium can be any usable medium which can be accessed by the computer and includes all volatile/non-volatile and removable/non-removable media. Further, the computer readable medium may include all computer storage and communication media. The computer storage medium includes all volatile/non-volatile and removable/non-removable media embodied by a certain method or technology for storing information such as computer readable instruction code, a data structure, a program module or other data. The communication medium typically includes the computer readable instruction code, the data structure, the program module, or other data of a modulated data signal such as a carrier wave, or other transmission mechanism, and includes information transmission mediums. 
     The system and method of the present disclosure has been explained in relation to a specific embodiment, but its components or a part or all of its operation can be embodied by using a computer system having general-purpose hardware architecture or desirably, a digital signal processing system to which an order of priority can be applied. 
     The above description of the present disclosure is provided for the purpose of illustration, and it would be understood by those skilled in the art that various changes and modifications may be made without changing technical conception and essential features of the present disclosure. Thus, it is clear that the above-described embodiments are illustrative in all aspects and do not limit the present disclosure. For example, each component described to be of a single type can be implemented in a distributed manner. Likewise, components described to be distributed can be implemented in a combined manner. 
     The scope of the present disclosure is defined by the following claims rather than by the detailed description of the embodiment. It shall be understood that all modifications and embodiments conceived from the meaning and scope of the claims and their equivalents are included in the scope of the present disclosure.