• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.193-195
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• 2011

강판재 사용에 있어 수소취성현상은 강판재가 고강도화됨에 따라 그 감수성이 커지는 것으로 알려져 있다. 특히 노출강판재의 경우, 표면으로부터 침투해 들어가는 수소에 의한 수소취화 거동에 대한 연구가 필요하다. 본 연구에서는 고강도 DP강을 시험편으로 하여, 음극전기분해법에 의해 수소를 강제주입시킨 후, DP강 표면하 subsurface zone의 수소취화 거동을 평가하고자 하였다. 미소경도분포 측정결과, 수소주입시간이 증가함에 따라 표면하 subsurface zone의 경도 또한 증가하는 것으로 조사되었다. 이는 수소에 의해 표면하 subsurface zone의 경화가 일어나 DP강의 기계적 특성에 영향을 미친것으로 판단된다. 미소경도분포의 측정결과와 미세조직 관찰결과로부터 수소임계침투깊이를 평가하였고, 이를 통해 DP강내 수소확산에 의한 수소임계침투깊이가 존재함을 확인할 수 있었다.

• Asia Marketing Journal
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• v.1 no.3
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• pp.120-140
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• 1999

Q 방법은 인간의 태도와 행동을 연구하기 위해 철학적, 심리학적, 통계적, 그리고 심리측정과 관련된 개념을 통합한 방법론으로서 인간의 주관성을 정량적으로 분석할 수 있는 특수한 통계기법이다. 소비자의 인식, 가치, 태도, 신념과 같은 개념을 객관적으로 연구할 수 있는 방법으로서 가설 생성을 위한 탐색적 연구와 이론의 검증과 같은 확인적 연구에서도 적용될 수 있다. 많은 수의 표본을 대상으로 한 횡단적 R 방법에 비하여 개인이나 소집단에 대한 깊이 있는 탐구가 가능하다는 점에서 소비자 행동 연구에 유용성이 매우 높다. 개인의 주관성을 바탕으로 한 소비자 개인의 특성과 차별성을 이해하는 것이 마케팅 분야의 핵심을 이루고 있음에도 불구하고 그 동안 소비자의 주관성에 대한 깊이 있는 접근이 이루어지지 못하였다. 1935년에 심리학 분야에서 개발된 Q방법은 이를 분석할 수 있는 컴퓨터 패키지의 보급과 더불어 사회과학 전반에 걸쳐 그 활용이 확산되어 가고 있다. 이에 Q 방법의 과학철학적 특성과, 현재 널리 이용되고 있는 변수 중심의 R 방법과의 차이, 그리고 컴퓨터 분석을 포함한 구체적인 Q 분석방법 및 관리적 활용상의 문제점에 대해 논의하였다

• Economic and Environmental Geology
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• v.29 no.6
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• pp.713-724
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• 1996

The time-series resident solute concentrations, monitored at two field plots using the automated 144-channel TDR system by Kim (this issue), are used to investigate the dominant transport mechanism at field scale. Two models, based on contradictory assumptions for describing the solute transport in the vadose zone, are fitted to the measured mean breakthrough curves (BTCs): the deterministic one-dimensional convection-dispersion model (CDE) and the stochastic-convective lognormal transfer function model (CLT). In addition, moment analysis has been performed using the probability density functions (pdfs) of the travel time of resident concentration. Results of moment analysis have shown that the first and second time moments of resident pdf are larger than those of flux pdf. Based on the time moments, expressed in function of model parameters, variance and dispersion of resident solute travel times are derived. The relationship between variance or dispersion of solute travel time and depth has been found to be identical for both the time-series flux and resident concentrations. Based on these relationships, the two models have been tested. However, due to the significant variations of transport properties across depth, the test has led to unreliable results. Consequently, the model performance has been evaluated based on predictability of the time-series resident BTCs at other depths after calibration at the first depth. The evaluation of model predictability has resulted in a clear conclusion that for both experimental sites the CLT model gives more accurate prediction than the CDE model. This suggests that solute transport at natural field soils is more likely governed by a stream tube model concept with correlated flow than a complete mixing model. Poor prediction of CDE model is attributed to the underestimation of solute spreading and thus resulting in an overprediction of peak concentration.

• Journal of the Korean Vacuum Society
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• v.3 no.1
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• pp.77-93
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• 1994

플라즈마 식각 공정에서의 미세구조 식각 연구를 위하여 두종류의 미세식각 진전 모델을 제시하 였다. 모델 1에서는 Knudsen 확산 정도를 나타내는 Thiele 계수($\Phi$2) 의 변화와 마스크의 하전에 의한 이온의 회적이 식각 패턴에 미치는 영향을 고찰하였으며 모델 2에서는 이온의 충돌에 의한 분산 효과가 식각 패턴에 미치는 영향을 살펴보았다. 반응성 라디칼과 확산저항이 수직방향으로의 긱각깊이를 감소 시켜 RIE Lag를 일으키며 마스크의 하전에 의한 이온의 회절에 의하여 "dovetailing"형태의 식각 패턴 형성의 원인 이 됨을 알 수 있었다. 모델 2의 결과로부터 쉬스 지역에서의 이온의 분산이 심화될수록 "bowing" 형태의 식각패턴이 두드러졌으며 RIE Laggus상이 증가하는 것으로 나타났다.gus상이 증가하는 것으로 나타났다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.87-88
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• 2010

A permeability of concrete is a very important factors evaluating durability. So, we are carrying out a lot of relational data bases and experiment regarding a permeability. In order to evaluate a permeability of concrete, we are proceeding study on the water penetration and diffusion in concrete by water pressure. Because a way to evaluate a permeability of concrete has a limit. We will present a good method of evaluating durability of concrete using the water penetration depth of concrete by water pressure. To carry this out, we executed experiment with penetration depth of concrete by water pressure and verified it though FEM analysis.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.778-784
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• 2003

The carbonation of concrete is one of the major factors that cause durability problems in concrete structures. The rate of carbonation depends largely upon the diffusivity of carbon dioxide in concrete. The purpose of this study is to identify the diffusion coefficients of carbon dioxide for various concrete mixtures. To this end, several series of tests have been planned and conducted. The test results indicate that the diffusion of carbon dioxide reached the steady-state within about five hours after exposure. The diffusion coefficient increases with the increase of water-cement ratio and decreases with the increase of relative humidity at the same water-cement ratio. The content of aggregates also influences the diffusivity of carbon dioxide in concrete. It was found that the diffusion coefficient of cement paste is larger than that of concrete or mortar. The experimental study of carbon dioxide diffusivity in this study will allow more realistic assessment of carbonation depth in concrete structures.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.325-334
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• 1996

Pepper plants were flooded at 0, 5, 10 and 15cm at seedling stage under the condition of greenhouse. Treatment of flooding times are 6, 12, 24, 48 and 120 hours. The results obtained are summarized as follows. Plant height, number of leaves, shoot and root fresh weight were not recovered the flooding damages regardless of flooding time and depth. Pepper plant died in flooding depth of 5cm or more for over 48 hours. Plants in fallen leaves were found at more than 5cm depth and 6 hours of floodings. Photosynthesis and respiration rate decreased in the 5cm flooding depth or more for 24 hours. Chlorophyll content and root activity decreased for 12 hours or more at all the flooding depth. Also, diffusion resistance of stomata cell increased as increased flooding time and depth. Diseases occurred remarkably in proportion to the depth and hours of flooding treatment. It was not possible to control the desease by fungicide, also then was no effects of foliar spray of urea. Weight of fruit per plant not decrease by the 12 hours of 0cm and the 6 hours of 5cm flooding but decreased at deeper and longer flooding. Average weight of a fruit increased. The yield could not expected in the depth of 5cm or more for over 48 hours, There was significant positive correlation between all the investigated characteristics of growth and yield. There was, however, negative correlation between number of leaf and diffusion resistance of stomata.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.197-198
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• 2021

The temperature and humidity inside concrete affects the depth of carbonation. In this study, the temperature and humidity inside concrete were predicted by the numerical method under the boundary conditions of ambient temperature, humidity, solar radiation, and wind. Using the results of the thermal humidity analysis, diffusion of carbon dioxide and the reaction of cement hydration products were calculated for carbonation depth.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.903-910
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• 1998

Ti:LiNbO$_3$ optical waveguides have been fabricated by Ti-diffusion in wet oxygen atmosphere. The fabrication conditions of furnace temperature, diffusion time and bubbler temperature were 105$0^{\circ}C$, 8 hours and 9$0^{\circ}C$, respectively and Ti thickness was varied from 700$\AA$ to 1500$\AA$. In this paper, the nearfield patterns, mode sizes (hirizontal/vertical) and insertion loss of waveguides were discussed at wavelength 1550 nm ad function of Ti thickness. With the planar waveguide, the effective index change and diffusion depth were calculated at 632.8nm using the prism coupling method. From these results, the best Ti thickness in our conditions seems like to by 1200$\AA$~1300$\AA$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.99-103
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• 2010

A new analytic solution was derived for the diffusion into or from an immobile zone of a rectangular 2-D pore. For a long time, the new solution converges to a traditional mobile-immobile zone (MIM) model, but only if the latter is used with an apparent initial concentration that is smaller by almost 20% than the true one. This is the tradeoff for using a simple MIM model instead of an exact model based on the diffusion equation. The mass-transfer coefficient was found to be constant for a sufficiently long time; it was proportional to the molecular diffusion and inversely proportional to the square of the pore depth. The mass-transfer coefficient was time-dependent for a sufficiently short time and may be significantly larger than its asymptotic value.