• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.126-126
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• 2012

기후변화는 전 세계적으로 다양한 영향을 미치고 있으며 특히, 홍수나 대설로 인한 수문변화에 영향을 준다. 본 연구는 준분포형 연속 모형인 SWAT (Soil and Water Assessment Tool)모형을 이용하여 우리나라 3대 대설지역에 속하는 다목적댐인 충주댐유역(6642.0 m)의 기후변화에 따른 융설이 수문과 수질에 미치는 영향을 분석하고자 한다. 먼저, 융설 모형의 매개변수인 적설분포면적감소곡선 (Snow Cover Depletion Curve; SCDC)을 구축하기 위하여 10년(2000-2010)동안의 Terra MODIS (MODerate resolution Imaging Spectroradiometer) 위성영상자료와 6개 기상관측소(충주, 제천, 원주, 영월, 대관령, 태백)의 최심적설자료를 이용하여 연도별 SCDC을 구축하였다. 구축 결과, 눈이 50% 피복 일 때 snow volume은 연 평균 0.47로 분석되었다. 이를 SWAT 모형에 적용하여 수문과 수질에 대한 적용성 평가를 실시한 결과, 유출의 경우 NSE는 융설기간 동안 평균 0.8, 전체기간은 평균 0.6으로 나타났으며 수질(Sediment, T-N, T-P)의 경우 각각 평균 0.72, 0.70, 0.85을 나타내었다. 미래 기후자료는 IPCC(Intergovernmental Panel on Climate Change)에서 제공하는 SRES(Special Report on Emission Scenarios) A1B, B1 기후변화시나리오의 HadCM3 모델의 결과 값을 이용하였으며 기간은 과거 30년 기후자료(1981-2010, baseline)를 바탕으로 2040s(2020-2059), 2080s(2060-2099)의 두 기간으로 나누어 각각 분석하였으며 기후변화 결과 값의 불확실성을 줄이고자 과거 자료와 GCM의 1981년에서 2000년까지의 값을 비교하여 온도와 강수량의 보정을 실시한 후 LARS-WG를 이용하여 온도와 강수량 자료를 구축하였다. SWAT 모형을 적용한 결과, 평균 1.92 증가한 것으로 나타났으며 유출은 융설기간(Nov-Apr)이 비융설기간(May-Oct)보다 10% 더 증가하였다. 본 연구에서는 SWAT 모형을 통한 유출 및 환경부하량 전망을 목표로 하여 미래 기후변화를 고려한 융설이 다목적댐에서의 유출과 수질 (Sediment, Total Nitrogen, Total Phosphorus)에 미치는 영향을 평가해 보고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.12
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• pp.1017-1026
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• 2014

A multi-perforated tube is generally installed between the muffler inlet and in front of selective catalytic reduction (SCR) catalysts in the integrated urea-SCR muffler system in order to disperse the urea-water solution spray uniformly and to make better use of the SCR catalyst, which would result in an increase nitrogen oxide ($NO_x$) reduction efficiency and a decrease in the ammonia slip. The effects of the multi-perforated tube orifice area ratios on the internal flow characteristics were investigated analytically by using a general-purpose commercial software package. From the results, it was clarified that the multi-perforated tube geometry sensitively affected the generation of the bulk swirling motion inside the plenum chamber set in front of the SCR catalyst and to the uniformity index of the velocity distribution produced at the inlet of the catalyst. To verify the analytical results, engine tests were carried out in the ESC and ETC modes. Results of these tests indicated that the larger flow model in the longitudinal direction showed the highest NOx reduction efficiency, which was a good agreement with the analytical results.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.32-32
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• 2020

하나의 수계 또는 용수구역 내에서 작물생육기간 동안 지하수자원 수요량의 집중적인 증가로 인해 지역적 지하수 고갈이 발생하여 농작물 피해가 발생하고 있으며 과잉양수로 인한 지하수위 하강으로 사용자간 갈등도 빈번하다. 또한, 기후변화로 인해 극한기후인 가뭄의 잦은 발생은 이러한 현상을 가속화 한다. 지하수 산출성이 좋은 대수층의 공간적 분포는 복잡한 지질구조로 인해 균일하지 않으며 같은 대수층 내에서도 양수 위치에 따라 산출성은 다르게 나타난다. 이러한 지하수 수요와 공급 및 대수층 분포로 인한 지하수자원 불균형의 해소를 위해 지하수가 풍부한 지역에서 부족한 지역으로 지하수를 공급하는 방법을 적용할 수 있다. 이때 기술적용 지역의 지하수 사용 상황 및 공급 가능량을 정량적으로 평가하고 이를 기반으로 지하수 공급을 제어하는 것이 매우 중요하다. 지하수자원의 수요-공급 불균형이 발생할 때 즉각적으로 대응하기 위해서는 실시간으로 지하수 현황을 감시하고 이를 기반으로 공급 가능량을 산정할 필요가 있으며 이는 정보통신기술(Information and Communication Technology, ICT)에 기반한 관정연계관리체계(Well Network System, WNS)를 구성하는 기술 중 하나인 관정군집제어 기술로 구현될 수 있다. 수계 내에 설치된 기존의 양수정과 새롭게 추가된 관측정들을 4G LTE 네트워크를 통해 하나의 관정군으로 묶고 중앙 서버를 통한 자료 분석 및 양수 펌프 제어를 통해 대수층의 공급 능력과 사용자의 수요 현황에 따른 지하수자원의 체계적 분배를 구현하고자 하였다. 관정군집제어는 관정별 지하수위 및 양수정 양수량을 실시간으로 관측하고 이를 분석서버에 전송하여 해당 지하수계의 공급 가능량 및 인접관정 간섭 등을 분석하여 양수정의 펌프를 실시간으로 제어하고 양수된 지하수를 수요 지역으로 이송한다. 본 연구를 통해 관정군집제어 기술의 구현에 필요한 구성요소를 정의하고 이에 대한 구현 방법을 기술하여 WNS를 구성하는 하나의 요소기술 모델로 제시하고자 하였다.

• Science of Emotion and Sensibility
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• v.14 no.1
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• pp.39-48
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• 2011

There still is a limitation in the usage of 3D clothes model in the production line due to the lack of compatibility between 3D modeling software, and its accurate 2D pattern making software, especially for free formed dress with tight fitted zone and draped part. In this study, obstacles in the 3D direct dress design process was overcome by solving the compatibility among each step of 3D virtual design process as well as adopting 3D-2D direct pattern development program called 2C-AN. Efficacy of making 2D pattern from 3D dress design using 2C-AN program developed by the authors was examined during the course of actual dress making process. Accurate ease over the fitted dress part was examined by 3D scanning technology, and the actual appearance of the draped part was compared with the simulation image of dress model. It was confirmed that the entire 3D design process and direct 2D pattern development proposed in this study was accurate enough to use in the 3D design process.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.2
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• pp.110-119
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• 2016

Purpose: This study is aimed to assess changes of stress distribution dependent on different connection lengths and placement of the fixture top relative to the ridge crest. Materials and methods: The internal-conical connection implant which has a hexagonal anti-rotation index was used for FEM analysis on stress distribution in accordance with connection length of fixture-abutment. Different connection lengths of 2.5 mm, 3.5 mm, and 4.5 mm were designed respectively with the top of the fixture flush with residual ridge crest level, or 2 mm above. Therefore, a total of 6 models were made for the FEM analysis. The load was 170 N and 30-degree tilted. Results: In all cases, the maximum von Mises stress was located adjacent to the top portion of the fixture and ridge crest in the bone. The longer the connection length was, the lower the maximum von Mises stress was in the fixture, abutment, screw and bone. The reduction rate of the maximum von Mises stress depending on increased connection length was greater in the case of the fixture top at 2 mm above the ridge crest versus flush with the ridge crest. Conclusion: It was found that the longer the connection length, the lower the maximum von Mises stress appears. Furthermore, it will help prevent mechanical or biological complications of implants.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.2
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• pp.119-127
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• 2012

Purpose: This study was performed to compare the stress distribution pattern of abutment-fixture connection area using 3-dimensional finite element model analysis when 5 different implant systems which have internal connection. Materials and methods: For the analysis, a finite element model of implant was designed to locate at first molar area. Stress distribution was observed when vertical load of 200 N was applied at several points on the occlusal surfaces of the implants, including center, points 1.5 mm, 3.0 mm away from center and oblique load of 200 N was applied $30^{\circ}$ inclined to the implant axis. The finite element model was analyzed by using of 3G. Author (PlassoTech, California, USA). Results: The DAS tech implant (internal step with no taper) showed more favorable stress distribution than other internally connected implants. AS compare to the situations when the loading was applied within the boundary of implants and an oblique loading was applied, it showed higher equivalent stress and equivalent elastic strain when the loading was applied beyond the boundary of implants. Regardless of loading condition, the abutments showed higher equivalent stress and equivalent elastic strain than the fixtures. Conclusion: When the occlusal contact is afforded, the distribution of stress varies depending on the design of connection area and the location of loading. More favorable stress distribution is expected when the contact load was applied within the diameter of fixtures and the DAS tech implant (internal step with no tapering) has more benefits than the other design of internally connected implants.

• The Journal of the Acoustical Society of Korea
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• v.41 no.3
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• pp.359-366
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• 2022

In this paper, we present the Korean menu-ordering Sentence Text-to-Speech (TTS) system using conformer-based FastSpeech2. Conformer is the convolution-augmented transformer, which was originally proposed in Speech Recognition. Combining two different structures, the Conformer extracts better local and global features. It comprises two half Feed Forward module at the front and the end, sandwiching the Multi-Head Self-Attention module and Convolution module. We introduce the Conformer in Korean TTS, as we know it works well in Korean Speech Recognition. For comparison between transformer-based TTS model and Conformer-based one, we train FastSpeech2 and Conformer-based FastSpeech2. We collected a phoneme-balanced data set and used this for training our models. This corpus comprises not only general conversation, but also menu-ordering conversation consisting mainly of loanwords. This data set is the solution to the current Korean TTS model's degradation in loanwords. As a result of generating a synthesized sound using ParallelWave Gan, the Conformer-based FastSpeech2 achieved superior performance of MOS 4.04. We confirm that the model performance improved when the same structure was changed from transformer to Conformer in the Korean TTS.

• Clinical and Experimental Pediatrics
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• v.48 no.11
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• pp.1179-1186
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• 2005

Purpose : A universal standard of the birth weight for gestational age cannot be made since girth weight distribution varies with race and other sociodemographic factors. This report aims to establish the birth weight distribution curve by gestational age, specific for Korean live births. Methods : We used the national birth certificate data of all live births in Korea from January 2001 to December 2003; for live births with gestational ages 24 weeks to 44 weeks(n=1,509,763), we obtained mean birth weigh, standard deviation and 10th, 25th, 50th, 75th and 90th percentile values for each gestational age group by one week increment. Then, we investigated the birth weight distribution of each gestational age group by the normal Gaussian model. To establish final standard values of Korean birth weight distribution by gestational age, we used the finite mixture model to eliminate erroneous birth slights for respective gestational ages. Results : For gestational ages 28 weeks 32 weeks, birth weight distribution showed a biologically implausible skewed tail or bimodal distribution. Following correction of the erroneous distribution by using the finite mixture model, the constructed curve of birth weight distribution was compared to those of other studies. The Korean birth weight percentile values were generally lower than those for Norwegians and North Americans, particularly after 37 weeks of gestation. The Korean curve was similar to that of Lubchenco both 50th and 90th percentiles, but generally the Korean curve had higher 10th percentile values. Conclusion : This birth weight distribution curve by gestational age is based on the most recent and the national population data compared to previous studies in Korea. We hope that for Korean infants, this curve will help clinicians in defining and managing the large for gestational age infants and also for infants with intrauterine growth retardation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.9
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• pp.67-74
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• 2009

For the surge currents like lightning currents containing high frequency components and the abnormal currents having high frequencies which cause the EMI(Electromagnetic interference) problems for the electronic devices and communication instruments, the linear grounding electrodes have the significantly composite impedance characteristics which are dependent on the frequency of the applied current. The impedance of a grounding electrode is not lowered by expanding the dimension of the grounding electrode, and the length of grounding electrode having the minimum value of the grounding impedance for each condition of frequency and soil characteristics is existent, and it is defined as Critical length. In this paper, the critical lengths for the vertically and horizontally-buried grounding electrodes are calculated by using the distributed parameter circuit model. The propriety of the simulations has been confirmed by comparing the simulated results with the measured results.

• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.112-117
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• 2002

A comparative investigation of an experimental and a simulation of chemical kinetics for NOx removal from silent(dielectric-barrier) discharges is presented. Several types of dielectric-barrier discharges were implemented depending upon the configuration of electrodes. The simulation was based on an approximate mathematical model for plasma cleaning of waste gas. The influence of non-uniform distributions of species due to the production of primary active particles in the streamer channel was taken into account. A comparison of observed experimental to the calculated removal efficiency of NOx showed acceptable agreement.