• Journal of the Korean GEO-environmental Society
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• v.11 no.5
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• pp.53-60
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• 2010

The comprehensive tests on unsaturated weathered granite soils are carried out to obtain the soil-water characteristic curve that is the one of the essential requisites to study the unsaturated soil. The weathered granite soils were obtained at Palgong mountain in Daegu. The existing test results have been carried out without overburden pressures and volume changes. In this study, the volumetric pressure plate extractor is improved to consider two factors such as overburden pressure and volume change. The applied overburden pressures were 0, 25, 50, 75, 100kPa and volume changes were measured at each phase. he results of this study are summarized as follows: As the overburden pressure increases, the volumetric water content decreases at the same matric suction and the air entry value increases and gradient of curve at the transition zone and the size of the hysteresis loops decreases. As the overburden pressure increases, the degree of saturation increases at the same matric suction and degree of saturation of the wetting curve is higher than that of dry curve. The SWCC with volume changes are slightly larger than those without volume changes. The general equation proposed by Fredlund & Xing(1994) to fit the experimental result of the SWCC indicates good agreement. The empirical parameters a, n, m as overburden pressure show similar inclination as the existing results.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.62-64
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• 2008

본 논문에서는 기존의 Particle Swarm Optimization (PSO) 알고리즘에 반발 속도 (Repulsion Velocity) 개념을 도입한 개선된 PSO 알고리즘을 제안하였다. 낮은 적합도를 가지는 지역을 멀리하는 성질을 모사한 것이 반발 속도의 개념이다. 반발 속도의 개념을 도입한 제안된 알고리즘은 기존의 알고리즘에 비해서, 더 좋은 수렴 특성을 가지고, 더 빠른 계산 특성을 가짐을 알 수 있었다. 시험 함수를 통해서 제안된 알고리즘의 검증을 수행하였고, 외전형 영구자석형 전동기의 최적화에 적용하여서 그 결과를 나타내었다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.213-214
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• 2015

용융 합금의 표면 장력은 도금, 용접등 금속 제조 공정중 큰 영향을 미치는 재료의 물성 중 하나이다. 표면 장력의 측정을 위해 다양한 방법이 개발 되었으며 많은 합금계에 대해 표면 장력값이 온도와 조성의 변화에 대해 알려져 있다. 그럼에도 불구하고 실험 측정의 어려움, 실용적인 다원계 합금에서의 표면 장력 측정치의 부족으로 인해 전술한 금속 제조 공정에서 나타나는 현상에 대한 해석에 사용하기에 아직 해결해야 할 부분들이 많이 있다. 본 연구에서는 표면 장력이 합금의 Gibbs free energy의 한 부분으로 기술되는 열역학 원리 및 표면 장력이 Gibbs energy 수식 내 표면적에 대응하는 포텐셜 함수로 얻을수 있다는 Pajarre등의 제안에 근거하여 용융합금의 표면 장력을 계산하는 방법을 제시한다. 다양한 열역학 성질과 상태도를 계산하기 위해 개발된 열역학 소프트웨어 및 데이터베이스를 활용하여 2원계-다원계 용융 합금의 표면장력을 계산하고 이를 알려진 실험 자료와 비교하였다. 철강 제품의 표면 도금에 사용되는 용융 아연 합금의 표면 장력을 전술한 방법을 통해 예측하고 그 결과를 토의한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.314-316
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• 2009

본 논문에서는 사상체질분류검사 설문지를 이용하여 사상체질을 진단할 때, 진단의 정확도를 향상시키기 위한 사상체질 분류 함수를 개발하기 위하여 퍼지 분류기를 이용한다. 본 연구에서 사용하는 데이터는 9개 한의과대학의 10개 부속한방병원에서 치료를 받은 환자들 중 각 병원의 사상체질전문의로부터 체질진단을 받고 최소한 4주 이상 사상체질 처방을 사용한 후 주 증상이 전반적으로 호전되어 체질이 확인된 환자 1,914명을 대상으로 하고 있다. 본 연구는 사상체질의학의 광제설을 토대로 환자의 성별을 분리 하였을 뿐만 아니라, 비만도를 추가적으로 분류하였으며, 체형기상, 용모사기, 성질재간, 병증약리 중 체형기상을 토대로 분류하였으며, 사상체질을 판별할 수 있도록 설계되고 구현되었다.

• Journal of the Korean Wood Science and Technology
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• v.28 no.2
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• pp.10-18
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• 2000

Nondestructive testing(NDT) by using ultrasonic sound is widely applied to wood for grading, moisture and defect detecting, estimating degree of decay, etc. Before practicing such application, basic relationships between ultrasonic transmission and wood properties shall be studied first. In this study, ultrasonic NDT was applied to larch and red pine to investigate the effects of moisture content and slope of grain on ultrasonic transmission speed. Specimens for testing about moisture content were prepared to have moisture content of green state, 30%, 20%, 10% and oven-dry state. Specimens for testing about slope of grain were prepared to have grain angle of 0, 15, 30, 45, 60, 75 and 90 degree in the tangential direction. Ultrasonic transmission speed was inversely proportional to moisture content in low range of moisture content under around 30% that was considered to be close to fiber saturation point. In high moisture content range above 30%, the ultrasonic transmission speed was almost constant. The same trend was observed in the relationships between compressive strength and moisture content. Slope of grain also had inversely proportional relationship with ultrasonic transmission speed and compressive strength. The relationship between compressive strength and ultrasonic transmission speed could be expressed by a linear equation.

• Journal of KIISE:Databases
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• v.33 no.7
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• pp.682-692
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• 2006

Searching for gene products which have similar biological functions are crucial for bioinformatics. Modern day biological databases provide the functional description of gene products using Gene Ontology(GO). In this paper, we propose a technique for semantic similarity search for gene products using the GO annotation information. For this purpose, an information-theoretic measure for semantic similarity between gene products is defined. And an algorithm for semantic similarity search using this measure is proposed. We adapt Fagin's Threshold Algorithm to process the semantic similarity query as follows. First, we redefine the threshold for our measure. This is because our similarity function is not monotonic. Then cluster-skipping and the access ordering of the inverted index lists are proposed to reduce the number of disk accesses. Experiments with real GO and annotation data show that GORank is efficient and scalable.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.3
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• pp.311-319
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• 2003

This paper aims at investigating the exact dynamic response of the system undergoing a exponential impact force from the viewpoints of conservations of momentum and energy. The midpoint method applied in the Newmark's family algorithm is found to be identical to the case of the application of the trapezoidal method which provides conservations of momentum and energy. For the linear impact force the mid point, the trapezoidal and the (n+1) point method exactly meet the conservation characteristics independent of the size of integration interval. On the other hand, constants for the dynamic motion resulting from the nonlinear impact are underestimated or overestimated by these method mentioned above. To overcome this indispensible error, the Simpson 1/3 method as one of multi step methods whose advantages is to use longer time interval with the same number of evaluation functions is adopted for the exact conservations of momentum and energy. Moreover, the suggested method is expected to expand the similar algorithm for the general dynamic motion including finite rotations.

• Composites Research
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• v.23 no.2
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• pp.24-30
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• 2010

Interfacial evaluation and hydrophobicity of Ni-nanopowder/epoxy composites were investigated for self-sensing and actuation. Contact resistance and resistivity were measured using gradient micro-specimens. The actuation of the composites in the electromagnetic field was studied with three wave functions, i.e., sine, triangle and square functions. Due tothe presence of hydrophobic domains on the heterogeneous surface, the static contact angle of Ni-nanopowder/epoxy nanocomposite wasabout $100^{\circ}$, which was rather lower than that for super-hydrophobicity. The dynamic contact angle showed the similar trend of static contact angle. Ni-nanopowder/epoxy composite was responded wellfor both self-sensing and actuation in electromagnetic field due to the intrinsic metal property of Ni-nanopowder. Displacement of the actuator of Ni-nanopowder/epoxy composite was evaluated to obtain the maximum and the optimum performance using laser displacement sensor as functions of the wave type, frequency, and voltage. Actuation of Ni-nanopowder/epoxy composites also increased as functions of applied frequency and voltage. Actuated strain increased more rapidly at sine wave with increasing voltage compared to those of triangle or rectangular waves.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.179-184
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• 2001

대부분의 제품 생산 시에는 시제품을 제작하여 이에 대한 성능 심사를 통해 미비한 부분을 보완하기 위한 재설계 작업과정을 필요로 한다. 설계 작업에 가장 중요한 부분인 특정 설계 변수에 대한 민감도의 파악은 설계 작업의 핵심적인 역할을 하고 있다. 대개의 경우 진동설계를 위한 설계변수로 구조물의 단위면적, 길이, 재료의 성질과 같은 물리적인 변수를 많이 활용하고 있으며 이러한 변수들에 대한 민감도 해석 기법들은 이미 많은 연구를 통해 실용화되고 있다. 그러나 이러한 변수만으로는 주어진 조건을 만족하도록 설계하기가 어려운 경우가 있다. 이런 경우는 부가구조물을 첨가하여 저진동 설계조건을 만족하는 구조물을 제작하는 것이 보편적이다. 한편, 구조물의 최적화 과정에서 고유진동수를 고려해야 하는 경우가 많다. 저주파 영역의 문제에서는 첫번째 고유진동수가 구조물의 진동량에 관계되는 중요한 요인이 되고, 또한 공진에 의한 문제가 발생했을 경우에는 고유진동수를 옮겨서 공진을 회피할 수 있기 때문이다. 본 연구에서는 에어컨 실외기의 진동을 저감하고 그로 인한 구조기인 소음을 저감하기 위하여 음압 레벨을 바탕으로 정한 관심 주파수 영역에 고유진동수가 존재하지 않도록 부가구조물을 최적화하였다. 최적화에 필요한 민감도는 신뢰성 있는 유한요소 모델을 구성하는 것이 쉽지 않으므로 실험으로 구한 주파수 응답함수를 이용하였다.

• Journal of the Korean Chemical Society
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• v.51 no.1
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• pp.7-13
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• 2007

The oxazole plays an important role in the binding of lexitropsin to the guanine-cytosine base pair from minor groove of DNA. The geometry optimization is performed with DFT calculations for the two possible conformations of the protonated oxazole. The proton affinities are calculated at B3LYP level of theory with 6-31G* basis set for the optimized geometry. It is found that the proton affinites of the conformations in which the oxazole nitrogen is the protonation center are greater than that of the conformations in which the oxazole oxygen is the protonation center. This result is in good agreement with molecular electrostatic potential (MEP) contour map. The proton affinities are also studied for various substituted oxazoles with the electron-donating and -withdrawing groups to estimate substitutent effect on the proton affinity at the hydrogen bonding site of the oxazoles. it is shown that the electron-donating substituents increase the proton affinity of oxazole, while the electron-withdrawing substituents decrease it.