• Journal of Astronomy and Space Sciences
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• v.16 no.1
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• pp.21-30
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• 1999

We perform CCD observations in VRI filters for AK Her during 3 nights in Feb 1997 and Mar 1998 at Mt. Sobaek National Observatory, and obtained 236 images in V, 198 in R, and 197 in I filter. From the data, we construct light curves which contain a pair primary and secondary minima and (O-C) diagram. We analyzed the obtained light curves of AK Her using the Wilson-Devinney code. From the analyses, we find that AK Her is more likely detached or semi-detached than contact system. From the (O-C) diagram, we find that the (O-C) residuals increases out of accordance with the expectation of Borkovits & Hegedus since 1990. However, we cannot identify cause of the periodic variation of the (O-C) residuals.

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.13-20
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• 2016

Most software is distributed as a binary file format, so reverse engineering is not easy. But Android is based on the Java and running on virtual machine. So, Android applications can be analyzed by reverse engineering tools. To overcome this problem, various obfuscation techniques are developed. In android environment, the Proguard is most widely used because it is included in the Android SDK distribution package. The Proguard can protect the Java source code from reverse engineering analysis. But it has no function to protect resources like images, sounds and databases. In this paper, we proposed and implemented resource obfuscation framework to protect resources of android application. We expect that this framework can protect android resources effectively.

• Journal of KIISE:Information Networking
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• v.29 no.5
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• pp.473-481
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• 2002

Decryption of encrypted malicious scripts is essential in order to analyze the scripts and to determine whether they are malicious. An effective decryption technique is one that is designed to consider the characteristics of the script languages rather than the specific encryption patterns. However, currently X-raying and emulation are not the proper techniques for the script because they were designed to decrypt binary malicious codes. In addition to that, heuristic techniques are unable to decrypt unknown script codes that use unknown encryption techniques. In this paper, we propose a new technique that will be able to decrypt malicious scripts based on analytical approach. we describe its implementation.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.3
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• pp.43-52
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• 2003

The new principle to measure a sizing degree by a contact angle was developed using an automatic determination of the 3-end point coordinates of the water droplet on a sheet, which could diminish the operator's bias during measurement. A constant amount of water was first placed on a sample sheet by a water dispenser, and then an image of the liquid droplet was captured by a digital camera and then transmitted to a computer. The program measuring for contact angle extracted a liquid contour by Gaussian function combined with a 8-direction chain code. The Euclidean equation was applied to the binary image of the liquid contour in order to measure the diameter of the contour. Finally, the contact angle of the liquid was calculated by using the diameter and the top coordinates. In addition, a surface free energy of the sample sheet and an elapsed time taken up to the complete absorption into the sheet were simultaneously measured with the contact angle.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.11
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• pp.79-85
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• 2004

A digitally-controlled analog-block inevitably undergoes the bang-bang oscillations which may cause a big amplitudes of the glitches if the oscillation occurs at the MSB transition points of a binary counter. The glitch results into the jitter noise for the case of the DLL. In this paper, we devise a new counter code that has the hysteresis in the bit transitions in order to prevent the transitions of the significant counter-bits at the locking state. The maximum clock jitter is simulated to considerably reduce over the voltage-temperature range guaranteed by specifications. The counter is employed to implement the high speed packet-base DRAM and contributes to the maximized valid data-window.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.64.1-64.1
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• 2017

접촉쌍성 EK Com은 0.2667일의 짧은 주기를 가진 만기형 식쌍성으로 광도곡선의 변화로 인해 연구자마다 이계의 하위 유형을 다르게 언급하여 하위유형의 혼동이 있는 천체이다. 우리는 소백산천문대에서 2009년 5월 VR 필터로, 2013년 2 ~ 5월 사이 BVRI 필터로, 2016년 1 ~ 4월 사이 R 필터로 CCD 측광 관측하여 3개의 새로운 광도곡선을 획득하였다. 우리의 관측 자료와 SuperWASP의 공개된 자료로부터 40개의 새로운 극심시각을 산출하였다. 이 극심시각을 포함하여 155개의 극심시각을 여러 문헌에서 수집하여 주기 연구를 수행한 결과, EK Com의 공전주기는 영년 주기 증가와 더불어 8.2년의 주기적인 변화가 겹쳐 변화함을 발견하였다. 이러한 주기 변화 원인에 대하여 살펴본 결과, 영년주기변화는 질량이 작은 별에서 큰 별로의 질량이동에 의하여 일어나고, 주기적인 변화는 질량이 큰 주성의 자기 활동에 의해 발생할 수 있음을 보였다. Wilson-Devinney code를 이용한 광도곡선 분석을 통하여 EK Com은 개기식이 부식에 있는 하위 유형 A라기 보다 주식에 있는 W형에 속하며, 모든 광도곡선에서 1개의 Hot spot과 1개의 Cool spot을 가진 모형이 가장 관측치를 잘 설명한다. W UMa형 별들의 HR도, 온도비, 질량의 그래프에서 EK Com은 W형 Group들이 있는 위치에 존재한다. 이는 광도곡선에서 유추한 EK Com의 하위 유형과도 일치한다.

• Journal of Korea Multimedia Society
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• v.7 no.1
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• pp.73-79
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• 2004

In this paper, we propose an efficient soft decision decoding algorithm for linear block codes. A conventional soft decision decoder have to invoke a hard decision decoder several times to estimate its soft decision values. However, in this method, we may not have candidate codewords, thus it is very difficult to produce soft decision values. We solve this problem by introducing an efficient algorithm to search candidate codewords. By using this, we can highly reduce the cases we cannot find candidate codewords. We estimate the performance of the proposed algorithm by using the computer simulations. The simulation is performed for binary (63, 36) BCH code in fading channel.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.219-222
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• 2013

The Side Channel attack methods proposed by P.Kocher are mainly used for cryptanalysis different cipher algorithms even though they are claimed to be strongly secured. Those kinds of attacks depend on environment implementation especially on the hardware implementation of the algorithm to the crypto module. side-channel attacks are a type of attack introduced by P.Kocher and is applicable according to each environment or method that is designed. This kind of attack can analyze and also extract important information by reading the binary code data via measurement of changes in electricity(voltage) consumption, running time, error output and sounds. Thus, in this paper, we discuss recent SPA and DPA attacks as well as recent countermeasure techniques.

• Journal of Broadcast Engineering
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• v.1 no.1
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• pp.29-34
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• 1996

In data transmission system, some data are more sensitive to channel errors. Unequal error protection method increases transmission reliability by protecting channel error sensitive data more than other data. However, this method cannot be directly applied to vector quantized signals which are designed by LBG algorithm that assumes no channel distortion in the design, process. Therefore, in this paper, to apply unequal error protection to vector quantized signals, we propose a method which systematically assigns binary indexes to code vectors. We applied the proposed method to the transmission of vector quantized first-order Gauss-Marcov signals assuming that the percentage of the important data is 50%

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11C
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• pp.874-879
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• 2008

In this paper, a new extending method of q-ary low correlation zone(LCZ) sequence sets is proposed, which is a generalization of binary LCZ sequence set by Kim, Jang, No, and Chung. Using this method, q-ary LCZ sequence set with parameters (N,M,L,${\epsilon}$) is extended as a q-ary LCZ sequence set with parameters (pN,pM,p[(L+1)/p]-1,p${\epsilon}$), where p is prime and p|q.