Judul: Pengaruh Tingkat Konsentrasi Larutan Urea dan Garam terhadap Sifat Fisik dan Mekanik Kayu Kamper (Drybalanops aromatica)
Abstrak: Kayu dengan sifat higroskopisnya, mampu menyerap uap air yang ada di sekelilingnya, sehingga mengakibatkan terjadinya penyusutan dan pengembangan. Penyusutan dan pengembangan akan menyebabkan terjadinya perubahan bentuk pada kayu. Bila hal ini terjadi maka akan dikatakan kayu memiliki stabilitas yang rendah.
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Judul: Pengaruh lama perendaman dalam larutan urea dan garam terhadap sifat fisis dan mekanis kayu kamper (Dryobalanops sp.)
Abstrak: Kayu mempunyai sifat yang unik dibanding bahan lain yaitu bersifat higroskopis. Bila kayu berada dalam keseimbangan, kemudian udara sekitarnya menjadi lebih kering, maka kayu akan melepaskan air; sebaliknya apabila udara menjadi lembab, maka kayu akan menyerap air sampai kembali mencapai keseimbangan. Penggunaan larutan urea dan garam mampu mengurangi kembang susut kayu, karena kedua zat tersebut berfungsi sebagai bulking agent. Adanya bulking agent akan meningkatkan kestabilan dimensi kayu karena zat tersebut menggantikan dan mengisi ruang-ruang kecil (mikrovoid) dalam dinding sel yang biasa ditempati oleh air dan uap air. Penelitian ini bertujuan untuk mengetahui pengaruh lamanya perendaman dalam larutan urea maupun garam terhadap sifat fisis dan mekanis kayu kamper (Dryobalanops sp). Lama Perendamannya adalah 0 (hari/kontrol), 1 hari, 2 hari dan tiga hari.
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Judul: Algorithm construction of HLI hash function
Abstrak: Cryptography is a study of mathematical techniques related to aspects of information security regarding on confidentiality, data integrity, entity authentication, and data origin authentication. Data integrity is a service, which is associated with the conversion of data carried out by unauthorized parties. To maintain data integrity, one can use hash functions. An hash function is a computationally efficient function to map an arbitrary length bitstring to a fixed length bitstring called as hash value. The use of hash function in maintaining the information integrity and authentication is in digital signatures, virus protection, and software distribution. Illustration of the hash function in the integrity and authentication of information that is emailed as follow. The sender sends the information and hash value to the recipient. If the hash value of the information is equal to the hash value that is sent by the sender, then information has not been changed. Otherwise the information has been changed. An hash function has two properties, one way and collision resistance. An hash function is called one way if it is computationally infeasible to find any input such that when given any hash value . Meanwhile an hash function is called collision resistant if it is computationally infeasible to find any two inputs where such that . The purpose of this study is to construct a HLI hash function algorithm, to analyze the speed and security of the hash functions as a results of construction. Furthermore, it is to compare it with SWIFFT. Hash function is constructed based on the result of algebraic operations on modular polynomial ringwith . Modular polynomial ring noted as is a set of all polynomials of degree at most with coefficients in . can be represented as a set of integer vector of modulo in dimension . So, it is simple to implement in a computer. In vector operations, is lattice . Furthermore, alattice that is defined from certain polynomial ring is called ideal lattice. HLI hash function is consists of addition and multiplication algorithm in the ring. Addition algorithm consists of sumation operations of modulo and multiplication consists of multiplication operations of modulo . Generally, algorithm of HLI hash function consists of multiplication operations of modulo and addition operations of modulo . However, if the input is binary number then multiplication algorithm only consists of multiplication operation of modulo , so algorithm of HLI hash function consists of multiplication operations of modulo and addtion operations of modulo . An hash function is secured if it has two properties, i.e., one way and collision resistance. HLI hash function hash is one way, it is following the proof of Micciancio. It is has collision resistant because of polynomial is irreducible over and monic. Moreover, it is proved that for every unit vector , the vector is small vector. If the input of hash function is a binary number then HLI hash function only involves addition operations of modulo . So the time that used almost same with SWIFFT. The excellence of HLI hash function is the key size smaller than SWIFFT. This effect on
Keyword: hash function, modular polynomial ring, lattice