• 대한전자공학회논문지SD
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• 제47권10호
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• pp.29-33
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• 2010

변형된 time mapped prime sequences를 time spreading pattern에 이용하여 다양한 wavelength-time codeword를 구현하는 방법을 연구하였다. 이 연구 결과 $P_t$ = 3 일 때는 autocorrelation sidelobe와 crosscorrelation을 1이하로 유지하며 사용하는 파장 수의 제곱에 해 당하는 wavelength-time codeword를 생성 할 수 있으며 $P_t$ = 5 와 $P_t$ = 7 일 때는 crosscorrelation을 1이하로 유지하면서 $P_w$개의 wavelength-time codeword에 대해서 autocorrelation sidelobe를 2이하로 제한하는 범위에서 역시 사용하는 파장 수의 제곱에 해당하는 wavelength-time codeword를 생성할 수 있다.

• 대한수학회보
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• 제50권2호
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• pp.407-416
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• 2013

Let E be an elliptic curve over $\mathbb{Q}$ and $p$ be a prime of good supersingular reduction for E. Although the Iwasawa theory of E over the cyclotomic ${\mathbb{Z}}_p$-extension of $\mathbb{Q}$ is well known to be fundamentally different from the case of good ordinary reduction at p, we are able to combine the method of our earlier paper with the theory of Kobayashi [5] and Pollack [8], to give an explicit upper bound for the number of copies of ${\mathbb{Q}}_p/{\mathbb{Z}}_p$ occurring in the $p$-primary part of the Tate-Shafarevich group of E over $\mathbb{Q}$.

• International Journal of Computer Science & Network Security
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• 제23권7호
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• pp.49-60
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• 2023

The amount of data generated by electronic systems through e-commerce, social networks, and data computation has risen. However, the security of data has always been a challenge. The problem is not with the quantity of data but how to secure the data by ensuring its confidentiality and privacy. Though there are several research on cloud data security, this study proposes a security scheme with the lowest execution time. The approach employs a non-linear time complexity to achieve data confidentiality and privacy. A symmetric algorithm dubbed the Non-Deterministic Cryptographic Scheme (NCS) is proposed to address the increased execution time of existing cryptographic schemes. NCS has linear time complexity with a low and unpredicted trend of execution times. It achieves confidentiality and privacy of data on the cloud by converting the plaintext into Ciphertext with a small number of iterations thereby decreasing the execution time but with high security. The algorithm is based on Good Prime Numbers, Linear Congruential Generator (LGC), Sliding Window Algorithm (SWA), and XOR gate. For the implementation in C, thirty different execution times were performed and their average was taken. A comparative analysis of the NCS was performed against AES, DES, and RSA algorithms based on key sizes of 128kb, 256kb, and 512kb using the dataset from Kaggle. The results showed the proposed NCS execution times were lower in comparison to AES, which had better execution time than DES with RSA having the longest. Contrary, to existing knowledge that execution time is relative to data size, the results obtained from the experiment indicated otherwise for the proposed NCS algorithm. With data sizes of 128kb, 256kb, and 512kb, the execution times in milliseconds were 38, 711, and 378 respectively. This validates the NCS as a Non-Deterministic Cryptographic Algorithm. The study findings hence are in support of the argument that data size does not determine the execution.

• 전기의세계
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• 제21권3호
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• pp.41-47
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• 1972

The requirements of a successful design for single phase induction motors with a high efficiency have, in recent years, led to the use of non-quadrature stator windings motors in which a high starting torque is a prime requisite. The capacitor motor is one of above machines in which various possible forms of asymmetry can be occur. These forms of asymmetry in the stator phase windings, encountered in machine designs, are 1) an asymmetrical disposition in space of their magnetic axes, 2) a difference in their effective number of turns, 3) a difference in the distribution of their coil groups per pole and 4) amounts of capacitance of an auxiary winding. In order to apply the effective performance prediction of these form to motors, mading of lower quality-domestic magnetic materials, the analysis and the experimental investigations of its sample motors are described in this paper. The utility of such a motor is demonstrated and it is shown that the effects- a good efficiency, good power factor and high starting torque-of the motor mechanism with non-quadrature stator phase windings can development disadvantages by using the lower quality-domestis magnetic materials.

• 동력기계공학회지
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• 제18권3호
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• pp.100-105
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• 2014

This study is to investigate the effect of thermo mechanical treatment on the mechanical properties of 316L stainless steel. ${\alpha}^{\prime}$ and ${\varepsilon}$-martensite was formed by deformation. With increasing number of thermo mechanical treatment, volume fraction of martensite was increased rapidly, and then unchanged. With increasing number of thermo mechanical treatment, hardness and strength was increased rapidly, and then unchanged while elongation was decreased rapidly, and then unchanged. With increasing volume fraction of martensite formed by thermo mechanical treatment, hardness and strength was increased rapidly, elongation was decreased rapidly. Thus, hardness, strength and elongation of thermo mechanical treated 316L stainless steel was strongly affected by martensite formed by thermo mechanical treatment. Good combination of strength and elongation was obtained from thermomechanical treatment.

• 대한기계학회논문집B
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• 제22권9호
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• pp.1217-1228
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• 1998

In order to elucidate the operational characteristics of rotating heat pipes, the internal flow patterns and heat transfer performance are investigated. Flow patterns and its transition are studied with various rotational speeds by visualizing flows established inside a rotating tube. To verify those results of analysis, 2 heat pipes of the same geometries but fill charge rates of 7, 30% were manufactured and submitted to operating tests. Comparison of experimental results on heat transfer rate show a fairly good agreement with the analytical results. The analysis reveals that the optimum charge ratio is ranged in 4~7% depending on the quantity of thermal loads. but the heat pipe with 7% of fill charge ratio reached dry-out limitation at heat flux of $q^{{\prime}{\prime}}=6.2kW/m^2$ lower than that of analytic results. Transition of flow regime was well related to the correlation by Semena & Khmelev on transient centrifugal Froude Number Frc. But hysteresis phenomenon was observed in transition of flow regime, when the rotational speed was stepwisely changed in the way to undergo 1 cycle.

• 한국통신학회논문지
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• 제18권11호
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• pp.1735-1741
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• 1993

주파수 도약 다원접속 통신시스템에 사용될 수 있는 우수한 해밍자기상관성 및 타 상관성 그리고 긴주기를 갖는 새로운 주파수 도약 패턴순이 소개되었다. 주파수 도략 패턴순의 주기는 qk-1, 알파벧 크기는 q, 주파수 도약 패턴군의 크기는 q인데, 여기서 k는 임의의 양의정수 그리고 q는 소수의 정수승이다. 자시상관함수 및 타 상관함수의 최대값은 qk-1(trivial 경우 제외)인데 이것은 최적의 해밍 상관함수에 해당된다. 그리고 주파수 도약 패턴에 있어서 q*q 스퀘어당 평균 충돌의 수는 1보다 작다.

• Acta Via Serica
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• 제5권1호
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• pp.121-152
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• 2020

The article is a critical examination of the political developments in Armenia since the 'Velvet Revolution' of April-May 2018, when, on the wave of massive protests against the ruling regime, new young forces came to power raising amongst broad segments of population enormous enthusiasm and hopes about radical reforms that would lead to profound transformations in the political and socio-economic spheres. It contains a thorough analysis of underlying political processes in the country in an attempt to answer a number of topical questions, so important to get a deeper understanding of the situation in Armenia and in the South Caucasus region. Based on the analysis of the new authorities' performance against the acknowledged benchmarks and standards of democracy consolidation, such as: separation of powers, independence of the judiciary, good governance, transitional justice the author comes to the conclusion that they failed to achieve any breakthrough in the above-mentioned fields. On the contrary, as demonstrated by concrete examples, what occurred in Armenia was not a revolution but a mere regime change under the leadership of Prime Minister Pashinyan, who gradually has concentrated in his hands executive, legislative, and quasi-totality of the judicial branch of power.

• Advances in aircraft and spacecraft science
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• 제4권4호
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• pp.449-465
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• 2017

The aim of the present work is to present a computational study of the non-linear aero-elastic behavior of a multi-layered Thermal Protection System (TPS). The severity of atmospheric re-entry conditions is due to the combination of high temperatures, high pressures and high velocities, and thus the aero-elastic behavior of flexible structures can be difficult to assess. In order to validate the specific computational model and the overall strategy for structural and aerodynamics analyses of flexible structures, the simplified TPS sample tested in the 8' High Temperature Tunnel (HTT) at NASA LaRC has been selected as a baseline for the validation of the present work. The von $K{\acute{a}}rm{\acute{a}}n^{\prime}s$ three dimensional large deflection theory for the structure and a hybrid Raleigh-Ritz-Galerkin approach, combined with the first order Piston Theory to describe the aerodynamic flow, have been used to derive the equations of motion. The paper shows that a good description of the physical behavior of the fabric is possible with the proposed approach. The model is further applied to investigate structural and aero-elastic influence of the number of the layers and the stitching pattern.

• 동아시아식생활학회지
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• 제24권4호
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• pp.488-502
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• 2014

Research on the actual state of healthy Korean food menu items made from environmentally-friendly organic foods showed that 65.6% of subjects had experience of purchasing environmentally-friendly organic foods, and both genders chose 'expensive but reliable' as their prime reason for purchasing. Having no experience of purchasing environmentally-friendly foods constituted 34.5% of respondents, and the reasons were 'high price' and 'finding no difference from ordinary food'. Research on awareness of healthy Korean food menu items made from environmentally-friendly organic ingredients showed that both men and women thought the given menu items were 'fresh' but had little awareness of other factors such as 'good value for price', 'good visual style' and 'various recipes'. Regarding development prospective of environmentally-friendly organic foods, the number of subjects who answered positively was 405 (93%), which indicates that most research subjects showed positive attitudes. Top-selling menu items in the grain section were Sundubu-jjigae, Dubu-kimchi and Jeonju-bibimbap, and pajeon took first place in the vegetable selection. Moreover, Imjasu-tang showed high scores in the meat section. Furthermore, research on menu selection showed that menu selection was usually dependent on 'the price of menu (3.86)', 'fresh ingredients (4.03)', 'harmony of color (3.65)' and 'mood of the day (3.25)'. Research on menu selection revealed that 'quality of food' factors had the greatest influence upon preference and purchase intention for environmentally-friendly organic foods. Visual and psychological factors and values had significant an effect. Therefore, the food service industry should use this study as a source to develop menu items, by considering quality and visual factors. In addition, there should be various research performed on marketing strategies about menus from using environmentally-friendly organic foods and high value products.