• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.234-235
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• 2012

본 논문에서는 최근 표준화 활동이 진행 중인 HEVC(high efficiency video coding) 표준의 무손실 부호화 모드를 위한 효율적인 계수 주사 방법을 제안한다. 일반적으로 무손실 비디오 부호기에서는 부호화 손실을 없애기 위해 변환 및 양자화 모듈이 제거된다. 이 경우 부호화해야 할 잔여데이터는 양자화된 변환 계수가 아닌 예측 후의 차분 화소이므로 잔여데이터의 확률 분포가 변화된다. 제안한 방법에서는 무손실 부호화에서 화면내 예측 모드 별 잔여데이터의 발생 확률을 분석하고, 이를 고려해 역방향 모드 기반 차분 화소 주사 방법을 사용한다. 일반적으로 참조 화소와의 거리가 멀어질수록 예측 정확도가 떨어져 잔여데이터의 발생 확률이 높아지기 때문에 제안한 역방향 주사 방법을 사용하면 잔여데이터 부호화에서 이득을 얻을 수 있다. 실험을 통해, 제안한 방법이 HEVC 무손실 부호화에 비해 약 1.7%의 부호화 성능을 향상시키는 것을 확인했다.

• Journal of the KSME
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• v.34 no.12
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• pp.940-960
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• 1994

열설계과정을 요약 정리하면서 미국, 독일, 일본 등의 기계학회(또는 기술자협회)에서 보일러 및 소각로 등의 설계과정을 표준화하기 위하여 많은 노력을 기울여 왔음을 볼 수 있었다. 설계에 적용되는 주요 공식, 물성, 열전달 계수 등과 같은 자료를 공업표준이나 학회 또는 기술자협회의 지침서 형태로 공유하는 것이 공학발전에 유익하다는 사례를 확인할 수 있었다. 이를 종합하면 우리의 나아갈 바를 생각하는 좋은 지표가 될 수 있을 것으로 보인다.

• Journal of Broadcast Engineering
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• v.16 no.6
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• pp.1036-1046
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• 2011

MPEG and VCEG have constituted a collaboration team called JCT-VC(Joint Collaborative Team on Video Coding) and have been developing HEVC(High Efficiency Video Coding) standard. All transform coefficients in a TU(Transform Unit) have been equally quantized according to the quantization and inverse quantization method which is used in HEVC standard. Such an equal quantization is not efficient because the transformed coefficients in the TU are not eqully distributed. Furthermore, the quantized coefficients which is positioned in later scanning order cannot be efficient due to the entropy scanning method. We suggest an algorithm that transform coefficients are quantized at different values according to the position in TU considering a scanning order of entropy encoding to improve the coding efficiency. The principle of this algorithm is that quantization and inverse quantization are carried out according to the scanning order which is in accordance with the statistical characteristic of distribution of quantized transform coefficients. The proposed algorithm shows on the average of 0.34% Y BD-rate compression rate improvement.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.227-227
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• 2012

본 연구는 수자원계획 문제에서 다기준 의사결정기법을 적용할 때 발생할 수 있는 두 가지 문제에 대해 분석하였다. 첫 번째는 다기준 의사결정기법 선택의 차이가 결과에 어느 정도 영향을 미칠 수 있는지를 제시하였고 두 번째는 평가기준에 대한 가중치와 대안들의 평가치에 대한 불확실성을 최소화하기 위해 민감도 분석을 수행하는 절차를 제시하였다. 첫 번째 문제를 위해 가중합계법, Compromise Programming, 계층화분석과정, 수정된 계층화 분석과정, 가중곱방법, TOPSIS, ELECTRE-2, Regime 방법을 사용하였다. 또한 최근 사용빈도가 높은 삼각형 Fuzzy 숫자와 다기준 의사결정기법을 결합한 기법에 대해서도 분석하였는데 Fuzzy WSM, Fuzzy 계층화분석과정, Fuzzy 수정 계층화분석과정, Fuzzy TOPSIS, Fuzzy Compromise Programming을 검토하였다. 분석결과 평가기준에 대한 가중치 조건과 표준화 방법이 동일한 상황에도 불구하고 조금씩 다른 순위를 제시하는 것으로 나타났다. 또한 다양한 MCDM 기법들을 적용해도 동일한 순위로 나타나는 대안들이 있었다. 따라서 다기준 의사결정기법을 사용한 수자원 관리계획을 수립할 때에는 다양한 분석기법을 활용해서 기법의 선택으로 인한 불확실성을 최소화해야 한다. 두 번째 문제는 평가기준에 대한 가중치와 대안의 효과 정량화 자료의 불확실성을 극복하기 위해 각각에 대한 민감도 분석을 수행하였다. 본 연구는 유량확보와 수질개선을 위한 수자원 계획 수립을 위해 가중합계법을 이용한 문제에 두 경우의 민감도 분석을 모두 수행하였다. 이 과정에서 결정계수와 민감도 계수를 산정하여 이용하였다. 본 연구는 향후 수자원 관리 및 계획 분야에서 다기준 의사결정기법을 적용할 때 사용될 수 있는 기초 가이드라인이 될 것이다.

• Journal of Bio-Environment Control
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• v.20 no.2
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• pp.72-77
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• 2011

The objective of the present study is to provide the basic data necessary for estimating the overall heat transfer coefficient of commercial plastic greenhouse. The heat flow through covering of greenhouses was measured and the variation of overall heat transfer coefficient was analyzed. Because the inside-outside temperature difference of greenhouse to indicate the stabilized overall heat transfer coefficient was different depending on the number of covering layers, the actual overall heat transfer coefficient should be decided in range of inside-outside temperature difference to make the coefficient constant for each covering method. The variation trend of the overall heat transfer coefficient according to the inside-outside temperature difference corresponded with the existing research results, but the specific values of temperature difference to present the stabilized overall heat transfer coefficient were different each other. The increase rates of overall heat transfer coefficient with wind speed were quite dissimilar among several research results and the quantity of heat loss through covering according to the wind speed in the double layers covered or curtained greenhouse was less than that in the single layer covered greenhouse. Because there was large variations among the values of overall heat transfer coefficient for the polyethylene film greenhouses, it was required to establish the standardized environmental condition for experiment measuring heat flow through covering in commercial greenhouse.

• Journal of the Korean Society of Hazard Mitigation
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• v.1 no.3 s.3
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• pp.111-122
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• 2001

A reliability analysis is conducted on the process in estimating frequency rainfalls. 39 year of annual maximum data in Seoul station are collected to analyze the reliability in the frequency analysis technique. Frequency analysis is carried out for the nine types of distribution function and three types of parameter estimation method which are currently used in Korea. Reliability Analysis is conducted for the frequency rainfalls determined by 3 types(maximum, median, selected) of method to select the adequate rainfall. Computed rainfalls of each duration and return period are standardized to find the distribution of the frequency rainfall. It shows that the resulting rainfall distribution fairly represents the normal distribution. Coefficient of variation of 0.0456 is computed to be used in estimating the reliability based design rainfall.

• Journal of the Korean Society of Radiology
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• v.6 no.1
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• pp.47-51
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• 2012

PET/CT is taken 1 hour after $^{18}F$-FDG(F-18-fluoro-2-deoxy-D-glucose) injection. However, these would be often delayed for more than 2 or 3 hours due to equipment fault or unexpected situation. In the study, SUV(standardized uptake value) were measured from got image over time according to the parts of the body. As a result, there were great and small decrease in liver(middle of the right hepatic lobe), fat(Lt pelvis), lung (Rt upper lobe), aorta(ascending aorta level) of the body in delayed image, and ${\Delta}$SUVmax was increase of 37% in bone only(L5 vertebral body) of the body. ${\Delta}$SUVmax was increase of 37.6% in lesion, and the contrast degree was greater because of uptake increase in lesion and uptake decrease in the normal body.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.1
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• pp.33-43
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• 2023

The National Institute of Standards and Technology (NIST), which is working on the Post-Quantum Cryptography (PQC) standardization project, announced four algorithms that have been finalized for standardization. In this paper, we demonstrate through experiments that private keys can be exposed by Correlation Power Analysis (CPA) and Differential Deep Learning Analysis (DDLA) attacks on polynomial coefficient-wise multiplication algorithms that operate in the process of generating signatures using CRYSTALS-Dilithium algorithm. As a result of the experiment on ARM-Cortex-M4, we succeeded in recovering the private key coefficient using CPA or DDLA attacks. In particular, when StandardScaler preprocessing and continuous wavelet transform applied power traces were used in the DDLA attack, the minimum number of power traces required for attacks is reduced and the Normalized Maximum Margines (NMM) value increased by about 3 times. Conseqently, the proposed methods significantly improves the attack performance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.33-40
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• 1988

In this study, effects of the density of soil and the confining pressure applied to the soil sample on the elastic moduli of subgrade soils are experimentally analyzed. Through investigation of subgrade materials of domestic expressways, five typical types of subgrade soils are selected for the experiments. A series of unconsolidated undrained triaxial tests is performed on samples prepared with various water contents and densities at the confining pressures of 1.02, 2.04, and $3.06kg/cm^2$. Initial tangent modulus is inferred from the unloading-reloading portion of the stress strain curve obtained during an individual loading-unloading-reloading test. As a result of the analysis, it is found that the effect of the confining pressure on the elastic modulus of subgrade material is well consistent with the equation proposed by Janbu, and that the elastic modulus can be related to the dry unit weight expressing the Janbu constants as exponentiial functions of it. It is also found that the water content has little effect on the elastic modulus for the samples with the degree of saturation less than 70%.

• The Journal of the Acoustical Society of Korea
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• v.30 no.1
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• pp.1-8
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• 2011

This paper presents a method for improving the performance of ISF coefficients quantizer through compensating the defect of the split structure vector quantization using the ordering property of ISF coefficients. And design the ISF coefficients quantizer for wideband speech codec using proposed method. The wideband speech codec uses split structure vector quantizer which could not use the correlation between ISF coefficients fully to reduce complexity and the size of codebook. The proposed algorithm uses the ordering property of ISF coefficients to overcome the defect. Using the ordering property, the codebook redundancy could be figured out. The codebook redundancy is replaced by the adaptive-extended codebook to improve the performance of the quantizer through using the ordering property, ISF coefficient prediction and interpolation of existing codebook. As a result, the proposed algorithm shows that the adaptive-extended codebook algorithm could get about 2 bit gains in comparison with the existing split structure ISF quantizer of AMR-WB (G.722.2) in the points of spectral distortion.