Judul: Penentuan Nilai Opsi Tipe Eropa dan Amerika Menggunakan Metode Binomial
Abstrak: Investors have purposes to obtain maximum returns, but they must be careful to invest their money because they may take risk. Therefore, they need products to reduce the risk. The products are called derivative products. There are many kinds of derivative products, such as options. An option is a type of contract between two parties. One party gives the other party a right to sell or to buy some assets in a certain price and in a certain period. Based on their execution time, there are two types of options i.e. European styles and American styles. European style options can only be exercised at expiration time, meanwhile American style options can be exercised at random time to the expiration time. In this paper, the option price at a discrete time will be determined by using binomial model. A binomial model is a model that describes asset price movements by assuming two possibilities of asset price movements in the future. Those are up and down. One-step binomial structures can be expanded into multistep binomial structures in order to approximate the option price. The application of one-step binomial model is used on the European option and multi-step binomial model is used on the American option. The acquired formula is applied to calculate the value of call option of PT Telekomunikasi Indonesia stocks in January 2012 based on the data of January to December 2011’s fluctuation of stock.
Keyword: American Style., European Style, Options, Binomial Model

Judul: Pemodelan Nilai Opsi Tipe Eropa
Abstrak: Option is the right to sell or buy a specified quantity of some underlying asset by paying a specified exercise price, on or before an expiration date. There are two basic types of options, calls and puts. A call option is the right to buy and a put option is the right to sell the underlying asset. There are two types of options according to its execution time, i.e. American and European options. American options can be exercised at any time the holder wishes until the expiration date, while European options can only be exercised on the expiration date. Modelling of option price usually is done analytically by determining solution of differential equation that is satisfied by the price of derivative asset, known as Black-Scholes equation. Because option price is a reflection of present value of expectation of difference between the exercise price and the stock price at expiration date, so it is necessary to study the option price through the concept of present value, as an alternative way to model the option price. The result of this study shows that modelling of option price using differential equation method and present value approach give the same option price. Furthermore the results of ilustration give informations about the relation of the option price with its parameters as follow: First, increase in the current stock price causes the call option price also to increase, while the put option price, on the contrary, will decrease. Second, increase in the exercise price causes the call option price to decrease, while the put option price will increase. Third, the longer the expiration time the call option price will be higher, while the put option price doesn’t have the same tendency, but it depends on other parameters. Fourth, increase in the interest rate causes the call option price to increase, while the put option price will decrease. Finally, increase in the volatility causes the price of both call option and put option will increase.
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Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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