• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.111-121
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• 2010

Purpose: This 3D-FEA study was performed to investigate the influence of marginal bone loss pattern around the implant to the stress distribution. Material and methods: From the right second premolar to the right second molar of the mandible was modeled according to the CT data of a dentate patient. Teeth were removed and an implant ($\Phi\;4.0{\times}10.0mm$) was placed in the first molar area. Twelve bone models were created; Studied bone loss conditions were horizontal bone loss and vertical bone loss, assumed bone loss patterns during biologic width formation, and pathologic vertical bone loss with or without cortification. Axial, buccolingual, and oblique force was applied independently to the center of the implant crown. The Maximum von Mises stress value and stress contour was observed and von Mises stresses at the measuring points were recorded. Results: The stress distribution patterns were similar in the non-resorption and horizontal resorption models, but differed from those in the vertical resorption models. Models assuming biologic width formation showed altered stress distribution, and weak bone to implant at the implant neck area seams accelerates stress generation. In case of vertical bone resorption, contact of cortical bone to the implant may positively affect the stress distribution.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.423-433
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• 2019

In order to predict the seabed topography change due to the construction of offshore wind power structures in the west-southern sea of Korea, field observations for tides, tidal currents, suspended sediment concentrations and seabed sediments were carried out at the same time. These data could be used for numerical simulation. In numerical experiments, the empirical constants for the suspended sediment flux were determined by the trial and error method. When a concentration distribution factor was 0.1 and a proportional constant was 0.05 in the suspended sediment equilibrium concentration formulae, the calculated suspended sediment concentrations were reasonably similar with the observed ones. Also, it was appropriate for the open boundary conditions of the suspended sediment when the south-east boundary corner was 11.0 times, the south-west was 0.5 times, the westnorth 1.0 times, the north-west was 1.0 times and the north-east was 1.0 times, respectively, using the time series of the observed suspended sediment concentrations. In this case, the depth change was smooth and not intermittent around the open boundaries. From these calibrations, the annual water depth change before and after construction of the offshore wind power structures was shown under 1 cm. The reason was that the used numerical model for the large scale grid could not reproduce a local scour phenomenon and they showed almost no significant velocity change over ± 2 cm/s because the jacket structures with small size diameter, about 1 m, were a water-permeable. Therefore, it was natural that there was a slight change on seabed topography in the study area.

• Journal of Korea Port Economic Association
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• v.34 no.4
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• pp.181-190
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• 2018

The goal of this study is empirically to investigate the asymmetric relationship between two variables using the dry cargo freight rates and raw material price data from January 2012 to May 2018. First, we estimate the asymmetry of macroeconomic indicators of commodity prices by using a two - step threshold cointegration test. Second, the asymmetric relation test of the trade balance of existing commodity price changes is tested by bypassing to the high frequency dry cargo freight rate index. As a result of the estimation, in contrast to the existing linear analysis, each boundary value for the lower limit and the upper limit has different asymmetry. This implies that the period of fluctuation of the sudden residual that causes irregular rate of return fluctuations does not establish a long term equilibrium relationship between the raw material price and the dry cargo freight rate. Therefore, in order to consider the sudden price change in the analysis, it is necessary to include the band of inaction that controls the irregular volatility, which is consistent with the asymmetry hypothesis.

• 한국노년학
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• v.37 no.3
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• pp.617-635
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• 2017

The aim of this study was to investigate both poverty and depression among older adults, focusing on the relationship of these two trajectories. For expanding the understanding about elderly poverty and depression, the study measured the longitudinal patterns of various transition in these two variables. The data for the study is 1st to 9th waves (2006-2014) of Korea Welfare Panel Study (KoWePS), and 4,431 older adults were used for the final analysis. For data analysis, Semi-parametric group-based modeling and Dual trajectory model were selected. The main results of this study were followings; First, The trajectory groups were identified: non-poverty, decrease poverty, increase poverty, remain high-poverty, chronic poverty groups and 4 trajectories of depression: stable, remain low-depression, risk of depression, chronic depression groups. Second, the study was tried to anticipate the longitudinal transition of poverty and depression status, and investigate the concurrent relationship in these two variables. It turned out that the stable poverty status led the stable depression, and vice versa. Based on these result, this study for elderly welfare were discussed to reduce risk for poverty and depression.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.1
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• pp.29-36
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• 2007

This study was carried out to develop a water quality simulation model for the evaluation of an ungauged watershed. For this purpose, the WASP5 model was selected and modified. The model consists of three sub-models, LOAD-M, DYN-M, and EUT-M. LOAD-M, an empirical model, estimates runoff loadings using point and non-point source data of villages. The Geum River Estuary watershed was selected to calibrate and verify the Modified-WASP5. The LOAD-M model was established using field data of water quality and quantity at the gauging stations of the watershed and was applied to the ungauged watersheds, taking the watershed properties into consideration. The result of water quality simulation using Modified-WASP5 shows that the observed average BOD data from Gongju and Ganggyeong were 2.6 mg/L and 2.8 mg/L, and the simulated data were 2.5 mg/L and 2.4 mg/L, respectively. Generally, simulation results were in good agreement with the observed data. This study focused on formulating an integrated model for evaluating ungauged watersheds. Even though simulation results varied slightly due to limited availability of data, the model developed in this study would be a useful tool for the assessment and management of ungauged watersheds.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1430-1434
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• 2005

금강 유역과 같이 복잡한 하천유역 시스템의 관리를 위해서는 시스템 요소들을 통합적으로 분석할 수 있는 효과적인 의사결정지원 도구가 필요하다. K-MODSIM 모형은 단기 물관리, 장기 운영계획, 가뭄 대비계획 및 물관련 분쟁 해결을 위해 보다 개선된 유역관리 전략을 수립하기 위한 컴퓨터 기반 도구로 개발되었으며, 본 연구에서는 K-MODSIM 모형에 저수지 운영률을 반영하여 유역의 용수배분을 평가하였다. 유역 저수지군 운영 환경 및 제약조건을 반영한 네트워크를 구성한 후, 두 단계의 모형 검정을 수행하였다. 먼저 물리적 검정을 통해서 전체 대상 수계의 상하류 물수지를 검토하고, 다음 단계인 운영 측면의 검정에서 물리적으로 나타나는 상황이 댐 운영이나 제약 조건 등에 부합하는지의 여부를 검토하였다. 대청댐과 용담댐의 통합 운영을 위한 최적 운영률의 개발은 동적계획법 소프트웨어인 CSUDP를 이용하여 수행하였으며, 여기서 사유한 접근법은 음해 추계학적 동적계획법이다. 이 접근방법은 유입량 시계열을 추계학적으로 모의발생시키고, CSUDP 모형은 모의발생시킨 유입량 시계열에 대한 최적운영률을 찾기 위해 사용하며, CSUDP의 최적화 결과에 대한 통계적인 분석을 통해 월단위 운영률을 도출하였다. K-MODSIM 모형에 저수지 운영률을 반영하여 유역의 용수배분을 평가하였다. 유역 저수지군 운영 환경 및 제약조건을 반영한 네트워크를 구성하고, 대청댐과 용담댐의 통합 운영을 위한 최적연계 운영를을 개발하여 다음과 같은 운영 시나리오들을 개발하고 평가하였다. $\cdot$ 금강수계에 대한 용당댐의 영향 평가 $\cdot$ 댐 연계운영시 수요량 변화에 따른 영향 평가 $\cdot$ 하도추적을 고려한 일별모형의 검증 개발된 운영률과 하도추적방법을 K-MODSIM 모형에서 검증하기 위해서 vb.net 스크립트 파일을 개발하여 적용하였다.L이하로 이를 유등천 상류부에 공급할 경우 유등천의 수질은 BOD 6.7mg/L, TN 9.80mg/L, TP 0.90mg/L를 나타낼 것으로 예측된다. 고도처리시설의 도입 후 금강 합류점에서 갑천의 예측 BOD는 7.4mg/L로 현재 9.0mg/L에 비하여 개선되지만 이는 금강수계 오염총량 관리계획의 시$\cdot$도 경계지점 목표수질인 5.9mg/L를 만족시키지 못하므로, 이를 만족시키기 위해서는 방류수 BOD 7.2mg/L이하로 처리해야 할 것으로 판단된다.which support only concepts or image features.방하는 것이 선계기준에 적합한 것으로 나타났다. 밸브 개폐에 따른 수압 변화를 모의한 결과 밸브 개폐도를 적절히 유지하여 필요수량의 확보 및 누수방지대책에 활용할 수 있을 것으로 판단된다.8R(mm)(r^2=0.84)$로 지수적으로 증가하는 경향을 나타내었다. 유거수량은 토성별로 양토를 1.0으로 기준할 때 사양토가 0.86으로 가장 작았고, 식양토 1.09, 식토 1.15로 평가되어 침투수에 비해 토성별 차이가 크게 나타났다. 이는 토성이 세립질일 수록 유거수의 저항이 작기 때문으로 생각된다. 경사에 따라서는 경사도가 증가할수록 증가하였으며 $10\% 경사일 때를 기준으로 $Ro(mm)=Ro_{10}{\times}0.797{\times}e^{-0.021s(\%)}$로 나타났다.천성 승모판 폐쇄 부전등을 초래하는 심각한 선천성 심질환이다. 그러나 진단 즉시 직접 좌관상동맥-대동맥 이식술로 수술적 교정을 해줌으로써 좋은 성적을 기대할 수 있음을 보여주었다.특히 교사들이 중요하게 인식하는 해방적 행동에 대한 목표를 강조하여 적용할 필요가 있음을 시사하고 있다.교하여 유의한 차이가 관찰되지 않았다. 또한 HSP 환자군에서도 $IL1RN^{*}2$ allele 빈도와

• Journal of the Korean Society for Railway
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• v.19 no.5
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• pp.629-637
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• 2016

In this paper, an investigation was conducted to evaluate the acoustic performance of low height noise barriers installed adjacent to rails; an easy-to-use approximation formula was suggested for the evaluation of insertion loss (IL), instead of using the boundary element method. At first, the acoustic performance of the low height noise barriers was measured in an anechoic chamber using a scaled down model; the overall IL according to the source location was analyzed with the equivalent IL contour line. Using the measurement results obtained from the scaled down model, an approximation formula was suggested for the IL of low height noise barriers having various shapes. Also, the prediction program was validated through a comparison between the actual measurement results in the anechoic chamber and the prediction results. Finally, using the prediction program, an approximation formula for IL was suggested for the low height noise absorption barriers. Considering the frequency characteristics of the noise sources of the train, the absorptive low height noise barriers have a 'ㄱ' type shape, a height of 1.0m, and a length of 0.5m when they are installed on the structure gauge for the train.

• Journal of Korea Water Resources Association
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• v.45 no.1
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• pp.29-37
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• 2012

This paper attempts to measure the economic benefits of tap water quality improvement using a specific case study of Ulsan, one of the large cities in Korea. To this end, we apply the contingent valuation (CV) method by employing a one-and-one-half bounded spike dichotomous choice question format. We surveyed a randomly selected sample of 400 households in Ulsan and asked respondents questions in person-toperson interviews about how they would willing to pay for the program. Respondents overall accepted the contingent market and were willing to contribute a significant amount (1,611 won), on average, per household per month. This willingness varies according to individual characteristics such as education level and income. The aggregate value of the program in Ulsan amounts to approximately 8 billion won per year.

• Journal of Korea Water Resources Association
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• v.53 no.8
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• pp.617-626
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• 2020

This study investigates changes of bifurcation discharge ratio, flow velocity distributions and characteristics of separation zone due to variation of bifurcation angle by using TELEMAC-2D model. When the bifurcation angle is reduced from 90° to 45° without changing the boundary conditions, the bifurcation discharge ratio increased by 1.5 times from 0.523 to 0.785 because of increasing the radius of curvatures, the inertia force of the downstream flow, and the pressure gradient by the downstream boundary conditions. The bifurcation discharge ratio increases non-linearly whenever the bifurcation angle decreases by 15° intervals from 90° to 45° in flow with the upstream Froude number of 0.45 to 0.74. In flow with a maximum Froude number of 0.74, the rate of increase for bifurcation discharge ratio is 31.1% and the minimum value. When the Froude number is 0.58, the bifurcation discharge ratio is 0.7 or less, and the maximum rate of increase for that ratio is 53.5%. As the upstream Froude number decreases less than 0.58, the bifurcation discharge ratio exceeds 0.7, and the rate of increase decreases. When the upstream Froude number is 0.4 higher, the dimensionless width and length changing ratio of the separation zone are about 2.56 and 5.5 times higher than in 0.4 or less.

• The Korean Journal of Petroleum Geology
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• v.2 no.2 s.3
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• pp.43-50
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• 1994

The geologic structure of Gongju Basin, which is a Cretaceous sedimentary basin located on the boundary of Gyeonggi Massif and Ogcheon Belt, is modeled by using gravity data and interpreted in relation with basin forming tectonism. The electrical survey with dipole-dipole array was also conducted to uncover the development of fractures in the two fault zones which form the boundaries of the basin. In the process of gravity data reduction, the terrain correction was performed by using the conic prism model, which showed better results specially for topography having a steep slope. The gravity model of the geologic structure of Gongju basin is obtained by forward modeling based on the surface geology and density inversion. It reveals that the width of the basin at its central part is about $4{\cal}km$ and about $2.5{\cal}km$ at the southern part. The depth of crystalline basement beneath sedimentary rocks of the basin is about $700{\~}400{\cal}m$ below the sea level and it is thinner in the center than in margin. The fault of the southeastern boundary appears more clearly than that of the northwestern boundary, and its fracture zone may extended to the depth of more than $1{\cal}km$. Therefore, it is thought that the tectonic movement along the fault in the southeastern boundary was much stronger. These results coincide with the appearance of broad low resistivity anomaly at the southeastern boundary of the basin in the resistivity section. The fracture zones having low density are also recognized inside the basin from the gravity model. The swelling feature of basement and the fractures in sedimentary rocks of the basin suggest that the compressional tectonic stress had also involved after the deposition of the Cretaceous sediments.