• 한국환경과학회지
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• 제15권7호
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• pp.635-642
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• 2006

Present study evaluated the low-temperature destruction of n-hexane and benzene using mesh-type transition-metal platinum(Pt)/stainless steel(SS) catalyst. The parameters tested for the evaluation of catalytic destruction efficiencies of the two volatile organic compounds(VOC) included input concentration, reaction time, reaction temperature, and surface area of catalyst. It was found that the input concentration affected the destruction efficiencies of n-hexane and benzene, but that this input-concentration effect depended upon VOC type. The destruction efficiencies increased as the reaction time increased, but they were similar between two reaction times for benzene(50 and 60 sec), thereby suggesting that high temperatures are not always proper for thermal destruction of VOCs, when considering the destruction efficiency and operation costs of thermal catalytic system together. Similar to the effects of the input concentration on destruction efficiency of VOCs, the reaction temperature influenced the destruction efficiencies of n-hexane and benzene, but this temperature effect depended upon VOC type. As expected, the destruction efficiencies of n-hexane increased as the surface area of catalyst, but for benzene, the increase rate was not significant, thereby suggesting that similar to the effects of the re- action temperature on destruction efficiency of VOCs, high catalyst surface areas are not always proper for economical thermal destruction of VOCs. Depending upon the inlet concentrations and reaction temperatures, almost 100% of both n-hexane and benzene could be destructed, The current results also suggested that when applying the mesh type transition Metal Pt/SS catalyst for the better catalytic pyrolysis of VOC, VOC type should be considered, along with reaction temperature, surface area of catalyst, reaction time and input concentration.

• 기술혁신학회지
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• 제19권1호
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• pp.1-28
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• 2016

현재 우리나라 혁신시스템은 기존의 성장 및 기술공급 위주의 발전전략이 한계를 노정하면서 새로운 전환기를 맞고 있다. 이에 새로운 혁신 경로 창출을 위한 과학기술 ICT 정책 패러다임 전환은 물론 지속가능한 에너지, 농업 농촌 등 다양한 영역에서의 시스템 전환이 필요한 상황이다. 리빙랩은 사용자 참여를 기반으로 하는 새로운 혁신모델이자 지속가능한 시스템 전환의 니치 실험으로서 유럽을 중심으로 논의되고 있다. 본 연구에서는 과학기술 ICT가 에너지 전환, 농업 농촌 시스템 전환, ICT 정책 패러다임의 전환에 적용된 리빙랩 사례를 살펴보고 우리나라에서의 시사점을 도출하였다. 유럽의 SusLab 프로젝트, C@R 프로그램, 대만의 리빙랩 사례 모두 사전기획 단계부터 지역 사용자의 배경과 경험을 적극적으로 수집하고, 사용자 주도의 혁신활동을 개발프로세스 전반에서 유지함으로써 다양한 전환 실험을 성공적으로 추진하였다. 이러한 결과는 중앙정부와 지자체가 리빙랩 도입을 검토하는 현 상황에 맞춰 다양한 시사점을 제공한다. 리빙랩은 국가 또는 지역 전반의 사회 기술시스템의 전환을 위한 전략적 니치 실험, 정책 간 연계통합의 수단, 새로운 지역혁신 모델로 활용될 수 있다. 또한 최근 혁신정책 패러다임에서 강조하고 있는 사용자 및 수요 측면을 반영한 정책통합을 실현할 수 있는 중요한 플랫폼이 될 수 있다.

• Journal of Welding and Joining
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• 제20권4호
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• pp.510-516
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• 2002

Recently the laser welding technology has been applied increasingly for the automotive bodies. But the lap joint laser welding for 3 dimensional automotive body is new while the butt joint laser welding is well known as the tailored blank technology. In this study, the process window was found for the full penetration welding of the lap joint of the 1mm-thick high strength steel sheets. The limit curves and characteristic curves were suggested to define the boundaries and the contour lines in a space of the welding speed and the gap size. The characteristics of the weld sectional geometry were used to determine the limit curves. They are bead width, penetration depth and sectional area. After the observed data was analysed carefully, it was noticed that there was a transition point at which the sectional shape was changed and the bead area jumped as the welding speed was increased. Also a new concept of 'input energy Per volume' was suggested to distinguish the difference at the transition Point. The difference of sectional areas at the transition point can be related to the dynamic keyhole phenomena.

• 한국주거학회논문집
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• 제25권6호
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• pp.19-26
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• 2014

This study aims to derive street design alternative which can be applied to residential area as the functions of land use have been changed. The main findings are as follows; First, the study area in this research is on the process of the functional transition from full residential use to residential-commercial mixed use with cafes and restaurants. Second, dead-end streets in residential areas needs to be widened in order to meet the increasing needs of pedestrians and cars. One of the suggested strategies is to remove fences on the dead-end streets. Third, based on the main findings, this research can suggest following policies. Citizen participation is necessary in building land use plans and space design in old residential areas. Citizens can participate in architectural and landscape contracts, district-unit plan with the help of experts such as urban planners and architects.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.378-382
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• 1999

We evaluated the effect of joining process such as contact method, shape of joined area and pressure on the electrical property of Bi-2223 superconducting tape. It was observed that the current capacity was reduced at the transition area of the joined tape and was significantly dependent on the uniaxial pressure. The lap-joined tape, fabricated with a pressure of 1,000-1,600 MPa, show the highest value of current capacity(80-90%) of the tape itself. It is believed the highest value of current capacity results from improvement in core density, contacting area and grain alignment, etc. In addition, the irreversible strain( ${\varepsilon}$ irrev) for the joined tape· was measured to be 0.1%, smaller than that of enjoined tape( ${\varepsilon}$ irrev = 0.3%). The decrease in the strength and irreversible strain for joined tape is believed to be due to the irregular geometry/morphology of the transition area of the tape.

• 한국자동차공학회논문집
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• 제1권3호
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• pp.34-45
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• 1993

This study aims to analyze the mixing characteristics of hydrogen considered as a new fuel for internal combustion engines. As the physical property of helium gas is similar to that of hydrogen, helium gas was used in this study. To analyze the steady and unsteady behavior of jet, helium gas was injected into the stationary atmosphere at the normal temperature and pressure. Concentration of helium gas in the center of jet flow is in inverse proportion with axial distance from the nozzle tip. This agrees with the free jet theory of Schlichting. The relative equation for dimensionless concentration to radial/axial distance the axial distance of potential core region, the cone angle a of the jet flow and the relative equation for arriving distance of the front of jet flow to the lapse of time are obtained. But free jet theory of Schlichting in the dimensionless concentration is not in agreement with the present experimental results of the distance of the radial direction. It needs more study. When the arrival frequency of jet flow is used as a parameter, the transition area changing from unsteady flow area into steady flow area becomes gradually wider downstream, but its ratio for the whole unsteady flow area gradually decreases.

• 한국환경생태학회지
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• 제16권3호
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• pp.223-232
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• 2002

자연생태계의 보전을 위한 지역구분을 위하여 백두대간(피재-도래기재) 구간을 조사한 식생조사 자료를 바탕으로 식생의 보전가치를 식생지수라는 것으로 수치화하는 방법을 제시해 보고자 한다. 식생지수는 생물다양성, 임분의 보전가치, 환경의 청정성, 임분의 역사성 입지의 생산성 등을 바탕으로 수치화하였다. 식생지수는 백두대간 관리범위 설정에 이용될 수 있을 것이라 사료된다. 식생지수 I의 경우 총 113개의 조사지 중에서 59개 지역 52.2%가 핵심지역에 속하고, 34개 지역 30.1%, 20개 지역 17.7%가 각각 완충지역과 전이지역에 속하는 것으로 나타났다. 식생지수II의 경우 49개 지역 43.4%가 핵심지역에 속하고, 38개 지역 33.6%, 26개 지역 23.0%가 각각 완충지역과 전이지역에 속하는 것으로 나타났다.

• Advances in aircraft and spacecraft science
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• 제5권4호
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• pp.431-444
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• 2018

Numerical simulations have been conducted to study the unstart/restart characteristics of an over-under turbine-based combined-cycle propulsion system (TBCC) inlet during the inlet transition phase. A dual-solution area exists according to the Kantrowitz theory, in which the inlet states may be different even with the same input parameters. The entire transition process was divided into five stages and the unstart/restart hysteresis loop for each stage was also obtained. These loops construct a hysteresis surface which separates the operating space of the engine into three parts: in which a) inlet can maintain a started state; b) inlet keeps an unstarted state; c) inlet state depends on its initial state. During the transition, the operation of the engine follows a certain order with different backpressures and splitter angles, namely control route, which may result in disparate inlet states. Nine control routes with different backpressures and transition stages were designed to illuminate the route-dependent behavior of the inlet. The control routes operating towards the unstart boundary can make the inlet transit from a started state into an unstarted one. But operating backward the same route cannot make the inlet restart, additional effort should be made.

• 대한임상검사과학회지
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• 제42권2호
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• pp.92-96
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• 2010

The National Health Insurance Corporation (NHIC) was performed population health checkup survey program with especially two target ages, 40 years and 66 years old that were called as "life transition period" for national collective prophylaxis of cardiovascular diseases in Korea. We were investigated and compared between two age groups with the serum levels of cholesterol and triglyceride from data of the survey in Daegu province, Korea at April, 2007. Data of one hundred persons per each age (40 years and 66 years old) were collected and investigated for risk factors for chronic degenerative diseases including serum lipid concentration, health habits of drinking, smoking, exercise etc. In spite of the definite difference of life transition of the each age, the transition from adolescence to adulthood at 40 years old, and from adulthood to senescence at 66 years old, there were no significant difference of total cholesterol and triglyceride between two age groups.

• 한국음향학회지
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• 제37권1호
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• pp.1-11
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• 2018

천해 환경에서 음파 전달은 경계면에 의해 구형 분산에서 원통형 분산으로 음파 전달 조건이 전환되는데, 이 지점을 음파 전달 조건의 변환점 (transition point)이라고 정의한다. 이론적으로 거리에 따른 전달손실을 이용하여 음파 전달 조건의 변환점을 계산할 수가 있으며, 본 논문에서는 포물선 방정식 기반 음향모델을 이용하여 Pekeris 도파관에서 송 수신기가 수층의 중심에 위치한 경우 전달손실을 모의한 후 변환점을 도출하였다. 계산된 변환점은 수층과 퇴적층의 음속비로 계산된 임계각으로 추정한 임계거리와 비교, 분석되었으며, 동일한 환경에서 수층에 음향채널이 존재하는 경우와 음원 수심 변화에 따른 변환점 변동성을 확인하였다. 최종적으로 2015년 5월, 제주도 서남쪽으로 약 65 km 떨어진 SAVEX15(Shallow Water Acoustic Variability EXperiment 2015) 실험에서 획득한 천해 환경에서의 거리에 따른 저 중주파수 음파 전달 실험의 전달손실 자료를 이용하여 실험 해역에서의 음파 전달 조건 변환점을 도출하였으며, 이를 실험해역의 해양환경과 비교를 통하여 음전달 특성을 파악하였다.