• Ocean Systems Engineering
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• 제4권1호
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• pp.1-19
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• 2014

Hydrodynamic coefficients strongly affect the dynamic performance of autonomous underwater vehicles (AUVs). A novel kind of underwater vehicle (Heavier-than-water AUV) with higher density than water is presented, which is different from conventional ones. RANS method and overlapping grids are used to simulate the flow field around the vehicle. Lifts, drags and moments of different attack and drift angles in steady state are calculated. The hydrodynamic performances and how the forces change with the attitude are analyzed according to the flow field structure. The steady-state results using overlapping grid method are compared with those of software FLUENT and wind tunnel tests. The calculation results show that the overlapping grid method can well simulate the viscous flow field around the underwater vehicle. Overlapping grid skills have also been used to figure out the planar-motion-mechanism (PMM) problem of Heavier-than-water AUV and forecast its hydrodynamic performance, verifying its effectiveness in dealing with the dynamic problems, which would be quite helpful for design and control of Heavier-than-water AUV and other underwater vehicles.

• Journal of Electrical Engineering and information Science
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• 제2권3호
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• pp.66-70
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• 1997

The steam generator level is susceptible to the nonminimum phase in dynamics due to the thermal reverse effects known as "shrink and swell" in a pressurized water reactor. A state feedback assisted control concept is presented for the change of dynamic performance to the minimum phase the concept incorporates a nonlinear digital observer as a part of the control system. The observer is deviced to estimate the state variables that provide the true indication of water inventory by compensating for shrink and swell effects. The concept is validated with implementation into the steam generator simulation model.

• 한국지리정보학회지
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• 제13권1호
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• pp.1-15
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• 2010

본 연구는 GIS 기반의 SWAT (Soil and Water Assessment Tools) 모형을 이용하여 탁수발생 잠재가능성 평가지표를 개발하고 수계별 탁수 관리방안 대책을 지원하기 위해 기후변화에 따른 안동호와 임하호 유역의 유출량과 부유사량의 변화특성을 분석하였다. 장래 기후변화자료는 IPCC (Intergovernmental Panel on Climate Change)에서 제공하는 A1B 기후변화시나리오의 MIROC3.2 hires 모델의 결과값을 이용하여 생성하였다. 과거의 기후자료(1977~2006)를 기반으로 20C3M (20th Century Climate Coupled Model) 모의값을 이용하여 강수와 온도를 보정한 뒤 CF (Change Factor) 기법으로 downscaling 하였다. 미래 기후변화 시나리오는 세 기간(2020s, 2050s, 2080s)으로 나누어 분석하였고, SWAT 모형과 연계하여 기후변화에 따른 유출량 및 부유사량의 변화를 산출하였다. 2020s, 2050s, 2080s 기간동안의 안동호와 임하호 유역의 유출량과 부유사량은 기준년도(2006)에 비해 증가하였고, 계절적인 분석에서도 봄, 가을, 겨울철 안동호와 임하호 유역의 유출량과 부유사량이 기준년도에 비해 증가하는 것으로 모의되었다. 단, 여름철 유량과 부유사량은 2020s에만 증가하고 2080s에는 감소하는 것으로 분석되었다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2017년도 학술발표회
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• pp.182-182
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• 2017

Many small island nations rely on groundwater as their only other source of freshwater in addition to rainwater harvesting. The volume of groundwater resource of small island nations are further limited by their smaller surface area and specific hydrogeology. The rapid growth of population and tourism has led to increasing water demands and pollution of available groundwater resources. The predicted climate change effects pose significant threats to the already vulnerable freshwater lens of small islands in the form of rise in sea level, coastal inundation, saltwater intrusion, varied pattern of precipitation leading to droughts and storm surges. The effects of climate change are further aggravated by manmade stresses like increased pumping. Thus small island water resources are highly threatened under the effects of climate change. But due to the limited technical and financial capacity most of the small island developing states were unable to conduct detailed technical investigations on the effects of climate change on their water resources. In this study, we investigate how well small island countries are preparing for climate change. The current state of freshwater resources, impacts of predicted climate change along with adaptation and management strategies planned and implemented by small island countries are reviewed. Proper assessment and management practices can aid in sustaining the groundwater resources of small islands under climate change.

• 대한화학회지
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• 제15권4호
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• pp.171-175
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• 1971

Significant structure theory has been applied to the viscosities of supercooled liquids with success. In the supercooled region, the effect of free volume decrease is so significant that the thermal effects on the solid-like volume must be considered properly. In addition, the two state theories proposed by Jhon and Eyring for water and Litovitz et al. for boron trioxide have been successfully applied to the structure change in the liquid state. Considered liquids are benzene, carbon tetrachloride, p-xylene, water and boron trioxide.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 전자세라믹스 센서 및 박막재료 반도체재료 일렉트렛트 및 응용기술
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• pp.104-107
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• 2000

It is well known that the state of existence of molecules on the surface of water changes during compression of the molecules. Electric methods, such as the measurement of the surface potential or displacement current, are also useful for investigating dynamic changes of the molecular state on the water surface during compression. Maxwell-Displacement-Current(MDC) measuring technique has been applied to the study of monolayers of Arachidic acid and L-$\alpha$-Dimyristoyl Phosphatidylcholine(L-$\alpha$-DMPC). The displacement current was generated from monolayers on a water surface by monolayer compression. Displacement current was generated in the gas state, gas/liquid state, and liquid state in the course of monolayer compression. The researchers examined diplacement current of electric conduction organic monolayer generated due to orient change of monolayers alkylchain.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.195-198
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• 2003

A small amount of cement can be added to the soil with high water content to improve its engineering properties. It is difficult to point out the exact time when liquified state of soil is transformed into semi-plastic or plastic states when high water content soil is hydrated by cement. In this study fall cone penetration are used to explain the phase change and compactable status of soil cement. And engineering properties of soil cement compacted in plastic state are investigated. Results reveal that fall cone penetration depth of 1mm or less is judged to a compactable state of soil-cement. Permeability and CBR values of soil cement increased with mixing ratio increased.

• 무역상무연구
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• 제72권
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• pp.185-210
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• 2016

The climate change has become one of the most important global issues that require global responses. As one of the leading contributions to climate change, greenhouse gas emissions and Ballast Water Management have attracted growing attention from the international community. The International Maritime Organization (IMO) received its mandate to regulate International Convention for the Control and Management of Ships' Ballast Water and Sediments in 2004. The convention requires that every vessel must be equipped Ballast Water Management System (BWMS) in 2017. Based on this situation, this study aims to analyze the present state and data from the exports of BWMS(HS842121). The results show that as the most leading country in the field, Germany has the largest market share (14.33%), Revealed Comparative Advantage (RCA) index 1.76, and Trade Specialization Index (TSI) 0.636 in the world. The two other leading countries such as Denmark and Netherlands follows the ability of Germany. The Korean market share of HS842121 shows market share (5.98%) which is a bit bellow high compared to other countries. However the RCA index (1.85) presents the state of comparative advantage. In addition, Korea's TSI index (0.453) indicates that it is in the state of export specialization. The Korean BWMS and Shipbuilding industry maintain the state of export specialization. They are also in the state of import specialty. For Korea to raise its export competitiveness and to ensure shipbuilding competitiveness, it is necessary to intensify supporting systems and related policies.

• Food Science and Biotechnology
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• 제16권5호
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• pp.783-788
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• 2007

An advantage to the extrusion of raw potatoes is a reduction in the energy input required to process potato products; however, the effects of extrusion on the properties of raw potato have not been studied. The purposes of this study were to develop a workable extrusion process for raw potato and to study the effects of extrusion conditions on the pasting properties of extruded potato products. The peak viscosity, final viscosity, pasting temperature, water solubility index, and water absorption index of pressed and pressed-dried potato extrudates decreased as die exit temperature increased, whereas they did not change as screw speed increased. The peak viscosity, final viscosity, and water solubility of steam-cooked potato products decreased with extrusion processing; however, they did not change with increasing die exit temperature and screw speed. Potato products with different degrees of depolymerization of extruded potato starch, depending on die exit temperature, were produced from raw potatoes.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.540-544
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• 2009

Hydrologic pattern under climate change has been paid attention to as one of the most important issues in hydrologic science group. Rainfall and runoff is a key element in the Earth's hydrological cycle, and associated with many different aspects such as water supply, flood prevention and river restoration. In this regard, a main objective of this study is to evaluate design flood using simulation techniques which can consider a full spectrum of uncertainty. Here we utilize a weather state based stochastic multivariate model as conditional probability model for simulating the rainfall field. A major premise of this study is that large scale climatic patterns are a major driver of such persistent year to year changes in rainfall probabilities. Uncertainty analysis in estimating design flood is inevitably needed to examine reliability for the estimated results. With regard to this point, this study applies a Bayesian Markov Chain Monte Carlo scheme to the NWS-PC rainfall-runoff model that has been widely used, and a case study is performed in Soyang Dam watershed in Korea. A comprehensive discussion on design flood under climate change is provided.