• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.1
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• pp.82-88
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• 2009

The structure of steady wave system is considered which is admitted by the continuum equations for materials that undergo phase transformations with exothermic chemical reaction. With its theoretical basis in one-dimensional continuum shock structure analysis, the present approach estimates the micro-width of waves associated with phase transformation phenomena, n-heptane is selected as the hydrocarbon fuel for evaporation and condensation analysis while HMX is used for melting and freezing analysis of solid rocket propellant. The estimated thickness of evaporation - condensation front of n-heptane is on the order of $10^{-2}$ micron while the HMX melting - freezing front thickness is estimated at 1 micron.

• Journal of the Korean Institute of Gas
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• v.3 no.1
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• pp.27-32
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• 1999

Chemical processes are highly nonlinear, multivariable systems and have complex structures. However, the controllability evaluation procedures are complicated, and the required information is very often unknown at the early design stage. Therefore, it is necessary to develop a procedure to evaluate and enhance controllability while designing processes and plants. To evaluate controllability in the design stage, it is most efficient to analyze process structure. Relative order can be used as a measure of 'physical closeness' between input and output variable. Structural controllability analysis using relative order is shown to be effective in a case study of heat exchanger network synthesis.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.104-104
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• 2023

최근 2017년 청주, 천안의 홍수, 2020년 용담댐 상류와 대청댐 상류의 홍수, 2022년 청주의 도시침수를 비롯한 서울 도심의 침수피해와 같은 홍수 발생은 지역의 국민들에게 막대한 재산상의 피해를 입히고 있다. 국가적 차원에서 치수의 목적을 달성하고 경제적으로 적절한 규모의 수리구조물을 설계하기 위해 하천의 주요지점에 대한 신뢰성 있는 설계홍수량의 제시는 반드시 필요한 현실에 직면해 있다. 특히 해당 지점의 수리시설물은 점빈도분석에 의한 설계홍수량을 적용하나, 관측자료가 없는 미계측 지점에 위치한 수리시설물은 지역빈도분석에 의한 설계홍수량을 산정하여 적용해야 한다. 이에 본 연구에서는 금강 유역을 대상으로 점빈도분석과 지역빈도분석에 의한 설계홍수량 결과를 비교·분석하고자 한다. 지역빈도분석을 위한 수위관측소의 선정은 금강유역 80개 수위관측소 중 장기간 연최대홍수량 자료가 있고 유량자료의 연결성 및 신뢰성이 확보된 46개수위관측소를 대상으로 하였다. 46개 수위관측소의 연최대홍수량 계열을 대상으로 동질성, 독립성 및 이상치 검정을 수행하였으며, 세 가지 검정 모두 적절한 수위 관측소 지점은 36개 지점으로 분석되었다. 36개 수위관측소의 기본통계치(평균, 표준편차, 분산, 왜곡도 및 첨예도)를 산정한 후 3변수 Gamma 분포 계열인 GEV, GLO, GPA의 확률 분포를 적용하였다. 확률 분포별 매개변수는 전산화를 통해 L-모멘트의 차수를 0~4까지 변화시켜 LH-모멘트법에 적용하였다. LH-모멘트법에 의해 산정된 확률 분포들의 매개변수를 적용하여 적합도 검정을 수행하였다. 지역빈도분석을 위해 36개 수위관측소를 K-Means clustering 방법을 통해 4개 지역으로 구분하였다. 이를 통해LH-모멘트의 적정차수와 확률 분포에 따른 점빈도분석(지점 대상)과 지역빈도분석(지역 대상) 결과인 설계홍수량을 산정하였으며, 점빈도분석과 지역빈도분석에 의해 산정된 설계홍수량간의 분석결과를 제시하였다. 본 연구를 통해 수리구조물 설계 시 안정적인 조건 제시 및 관리체계 구축에 기여하고 방재대책 수립 시 경제·사회적 요소를 반영한 합리적 방안을 제시하고자 한다.

• Journal of the Korean GEO-environmental Society
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• v.14 no.11
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• pp.33-46
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• 2013

Recently, the projects which are to increase the capacity of the flood control are being actively performed because of the abnormal climate changes throughout the country. In this study, the regression analysis was performed using both Kelvin model and the real settlement measured at the crest of the existing concrete face rockfill dam(CFRD) to estimate the long-term deformation behavior characteristics such as creep which occurs without additional load. In addition, the effects on changes in physical properties (E, G, K) of the dam construction materials by deformation characteristics of the dam were evaluated, and the reasonable stability analysis method of the dam was proposed to obtain the long-term stability considering the changes in physical properties induced by the long-term deformation behavior in case of heightening the existing dams.

• Journal of the Korean Society of Groundwater Environment
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• v.7 no.1
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• pp.1-7
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• 2000

In order to reduce the groundwater contamination around the Kimpo landfill in Korea by the leakage of the leachate within it, The method establishing 5 sets of Radial Collector Well Laterals(RCWLs) within the landfill, the method utilizing the wells dewatering the condensed water, the method establishing an interception wall to the 2nd layer at the circumference of the landfill and 22 sets of RCWLs within it, and the method establishing an interception wall to the 3rd layer and 40 sets of RCWLs were studied. Hydraulic parameters were measured for this study and then the groundwater flow and contaminant transport systems around the Kimpo landfill were analyzed with the MODFLOW and MT3D models. Conclusively, the method establishing an interception wall to the 2nd layer and 22 sets of RCWLs was evaluated as the most stable and economical option to reduce groundwater contamination concentration below drinking water standards.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.1
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• pp.13-20
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• 2012

In this study, the change pattern of hydrological response function as development has been observed. The target watershed was selected Tanbu sub-Basin in the Bocheong Basin. The applied channel networks are composed of 10 cases that are channel networks by strahler's ordering scheme and cases of all grids channel or the hillslope in basin. To each case of grid in basin, channel and hillslope drainage path lengths to outlet of basin are calculated, and hydrological response function was calculated by Nash Model. As results of this analysis, the peak discharge of hydrological response function is increased and peak time is shortened as development of channel networks. And based on statistical characteristics of hydrological response function, mean (lag time) and variance of travel time are reduced exponentially.

• ETRI Journal
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• v.14 no.1
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• pp.118-125
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• 1992

다중 컴퓨터 연결망의 성능은 그 위상에 따라 크게 좌우되는데 현재까지 연구된 많은 연결망중에서 특히 하이퍼큐브 연결망은 노드수에 비해 비교적 적은 차수와 지름을 갖고 symmetric 하며 순환적 구성 (recursive decomposition structure) 특성을 갖고 있어 여러가지 알고리즘의 사상이 용이하여 많이 사용되고 있다. 여기서는 $Akers^2$ 등에 의해 제안되어 스타 그래프 (star graph) 에 대해 성능분석을 하였다. 분석 척도로는 노드간 평균거리를 사용하였으며 메시지 분포는 $Reed^(1)$가 사용한 분포를 사용하였다. 분석결과 스타 그래프 연결망은 하이퍼큐브와 비슷한 성능을 보였으며 노드 수가 많아질수록 더 나은 성능을 보였다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.2
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• pp.67-75
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• 1997

The noise . vibration characteristics of Hypoid gears which were made from three seperate materials(SCM, TSCM, SNCM) under the identical process were investigated for the sake of durability improvement of differential gear compatible with low level noise gear set. For this study, we developed a rig experimental equipment which can perform close noise.vibration experiment of differential gear. Consequently, we could analyze the noise.vibration characteristics of final reduction gear by materials, and also we observed changes in both metallic structure and hardness according to the materials of pinion gear. In addition to this, the correlation between the vibration of the differential gear and the interior noise of the passenger vehicles was proved by analyzing the results of rig vibration experiment and field noise test.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.494-500
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• 2007

The comfort and quietness of vehicle has been improved greatly due to the development of technology in automobile industry. It is driven by reduction on the level of vibration and noise in powertrain system. However, the hidden problems in automobile parts become noticeable since the vehicle has been better in overall performance. One of them is related to the fuel pump system. Therefore, this study is focused on investigating the characteristics of fuel pump and fuel tank first, and then comparing the data before and after installation of fuel pump system in a testing vehicle. Additionally, the measured data will be analyzed to identify the problems and find a solution to improve the level of noise and vibration in fuel pump system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8C
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• pp.569-574
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• 2008

Noise predictive maximum likelihood(NPML) detector embeds noise prediction! whitening process in the branch metric calculation of Viterbi detector and improves the reliability. In this paper, some high-density optical storage channels are examined, and appropriate NPML systems are designed for each channel.