• 한국대기환경학회지
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• 제13권4호
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• pp.269-284
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• 1997

The ambient concentrations of gaseous and particulate phase ionic species and gaseous organic species in the Yochon industrial estate were measured during the spring ans summer of 1996. A three-stage filter pack sampler was used to collect particles and gaseous species, and stainless steel air sampling containers were used to collect air samples for organic species analyses. The concentrations of ions in aerosol wree comparable to those measured in Seoul. Aerosols measured were acidic, thus, most volatile acidic species were in the gas phase. The concentrations of organic species were highly variable, implying those were strongly dependent on the emissions of organic species from petrochemical plants. The concentrations of a few hazardous organic components were higher than those in Seoul or some populated areas in USA.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.177-183
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• 2008

For 10 kW-class Stirling engine using scroll expander and scroll compressor, considerations on thermal expansion of the fixed and orbiting scroll members of the scroll expander due to high gas temperature at the expander inlet has resulted in adopting of the keys between the fixed scroll and main frame for the fixed scroll side and spring type insertion between the orbiting scroll base plate and supporting holders for orbiting scroll side. Dynamic analysis on the fixed and orbiting scroll members and the shafts of the scroll expander showed that using of these devices for complying thermal expansion caused large variations of the forces acting on the fixed scroll keys and on the power transmitting shafts and also on the shaft bearings.

• 연구논문집
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• 통권30호
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• pp.25-32
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• 2000

A free piston and free displacer(FPFD) Stirling cryocooler for cooling infrared and cryo-sensors is currently under development at KIMM(Korea Institute of Machinery & Materials). A Stirling cryocooler is relatively compact, reliable, commercially available, and uses helium as a working fluid. The FPFD stirling cryocooler consists of two compressor pistons driven by linear motors which makes pressure waves and a pneumatically driven displacer piston with regenerator. The FPFD Stirling cryocooler employs 1) the Stirling cycle for refrigeration, 2) linear for driving the cryocooler, 3) spring and gas support systems, and 4) fine gap for clearance seals. It is the most suitable design for a mechanical cryocooler utilized in night vision environment. In order to get optimum operating frequency, natural frequency of piston and displacer, optimum phase angle between piston and displacer, cooling capacity, performance tests of the Stirling cryocooler by the frequency characteristics were performed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.220-223
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• 2009

Metallic bipolar plate for molten carbonate fuel cell(MCFC) is composed of the shielded slot plate and the center plate. Among these, the center plate plays an important role in gas sealing. Therefore, manufacturing of the center plate is considered one of the key issues in MCFC. The center plate is manufactured by bending process. In bending process, springback and recoiling are two main problems. By using the modified punch shape with 'step', springback and recoil are reduced. The aim of this article is to find the effect of modified punch shape. So, the bending stress along thickness direction and material direction were investigated using FEM.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2010년도 정기 학술대회
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• pp.480-483
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• 2010

착륙장치는 완충장치를 이용하여 항공기 착륙 시의 충격을 흡수하는 역할을 한다. 여러 방식의 완충장치가 있으나, Oil에 의한 감쇠력과 Gas에 의한 스프링력을 이용하여 에너지를 흡수하는 유공압 방식이 가장널리 사용되고 있다. 착륙장치 성능해석에서는 다양한 착륙조건에 대한 Dynamic simulation을 통해 최적의 Orifice 형상과 Gas spring 특성을 결정하고, 설계에 필요한 착륙하중을 구하게 된다. 이 논문에서는 상용 프로그램인 VI-Aircraft를 이용한 착륙장치 성능해석 과정을 소개한다. 유공압 완충장치의 모델링 및 Landing simulation 결과를 분석하고, 이에 따른 완충효율 최적화 과정을 제시한다.

• 항공우주기술
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• 제7권1호
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• pp.170-176
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• 2008

고체모터 추력제어를 위한 플렉시블 셀 개념 설계를 수행하였다. 개념 설계를 통해 플렉시블 씰의 구동 점 위치, 플렉시블 씰의 형상, 고무 및 보강재 소재를 결정하였으며, 연소가스로부터 플렉시블 씰을 보호하기 위한 적절한 열 차폐 시스템을 선정하였다. 플렉시블 씰의 회전 중심은 노즐 후방에 위치하며, 단면 형상은 원뿔형 으로 설계하였다. 노즐의 구동 토크를 만족하기 위해 고무의 전단 계수는 약 0.6MPa 이하가 되도록 개발 하였으며, 전단 응력은 2.5MPa 이상이다.

• 한국토양비료학회지
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• 제43권5호
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• pp.728-733
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• 2010

작형별로 봄감자, 가을감자로 구분하고 전과정평가를 통하여 감자생산체계를 원단위탄소성적과 이를 위한 LCI database 구축하였다. LCI 구축을 위한 영농 투입물 산출물에 대한 데이터 수집결과 봄감자는 특히 농약투입이 가을감자에 비하여 매우 높은 값을 나타내었고, 가을감자는 무기질비료 투입이 봄감자보다 많았다. 포장에서의 직접대기배출 ($CO_2$, $CH_4$, $N_2O$)은 봄감자와 가을감자가 각각 2.17E-02 kg $kg^{-1}$ potato 2.47E-02kg $kg^{-1}$ potato였다. 원단위 탄소성적은 봄감자가 8.38E-01 kg $CO_2$-eq. $kg^{-1}$ potato고, 가을감자가 8.10E-01kg $CO_2$-eq. $kg^{-1}$ potato였다. $CO_2$의 주요 발생요인은 비료생산공정이었고 (약 90%), 그 다음이 감자생산 (약6%)이었다. $N_2O$ 발생은 비료생산이 약 76%, 감자생산이 약 23%를 차지하였다. 평가 결과 봄감자의 GWP 특성화값은 8.38E-01 kg $CO_2$-eq. $kg^{-1}$이고, 가을감자는 8.10E-01 kg $CO_2$-eq. $kg^{-1}$였다.

• Journal of Korean Society for Atmospheric Environment
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• 제19권E1호
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• pp.29-39
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• 2003

The 10-day interval basis measurements of precipitation samples at Yangyang, the rural and coastal area on the eastern coast of the Korea peninsula were accomplished for understanding the precipitation chemistry and the temporal variations of major ions September 1991 to February 1997. The precipitation was slightly acidic, and 37% of the samples in winter were pH less than 4.5. The concentrations of cations were found on the order $Na^+\;>\;{NH_4}^+\;>\;Ca^{2+}\;>\;Mg^{2+}\;>\;K^+$ and those of anions followed the pattern $Cl^-\;>\;{SO_4}^{2-}\;>\;{NO_3}^-$. Neglecting sea salt components, the major ions controlling precipitation chemistry were nss-${SO_4}^{2-}$ and ${NO_3}^-$ in anion and ${NH_4}^+$ and nss-$Ca^{2+}$ in cation. Concentrations of these ions were lower than those measured at urban sites in Korea, but were higher than those measured in Japan. Most of nss-${SO_4}^{2-}$ and ${NO_3}^-$ were neutralized by ammonia and calcium species, especially alkaline soil particles in spring and ammonia gas in other seasons. Considering also the annual value of ［nss -${SO_4}^{2-}$］/［${NO_3}^-$］ ratio of 2.62 and the neutralizing factors, ammonium sulphate compounds were dominant. Annual mean concentrations of these ions showed relatively small fluctuations, while larger seasonal variations were observed with higher levels in spring and winter. Precipitation amount, influence extent of acidic gases and alkaline particles long-range transported from China continent, and energy consumption pattern in each season might be able to explain this seasonal trend.sonal trend.

• 한국산학기술학회논문지
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• 제1권2호
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• pp.1-8
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• 2000

본 연구에서는 상용 순수 티타늄 소재를 사용하여 안경테를 레이저 빔 용접으로 제조하기 위하여 광섬유로 전송되는 가변 펄스곡 80 ㎲-10 ms. 최대 평균출력 200 W, 첨두출력 12 kW와 최대 펄스에너지 50J성능의 초정밀 Nd:YAG 레이저 용접장치를 설계 제작하고 이 장치를 사용하여 안경테 제조를 위한 최적 용접조건을 선정하기 위한 실험을 수행하였다. 안경테를 위한 T이음 및 맞대기 이음형상을 용접할 때 평균출력, 광섬유 형태, 초점위치 등에서 용입상태와 용접결함을 조사하여 최적 용접조건을 선정하였고 안경테 부품 장석(temple hinge)과 다리, 톱바를 레이저 용접으로 시제품을 제작하였다.

• 한국토양비료학회지
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• 제49권6호
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• pp.720-730
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• 2016

Greenhouse-gas emission factors are widely used to estimate emissions arising from a defined unit of a specific activity. Such estimates are used both for international reporting to the United Nations Framework Convention on Climate Change (UNFCCC) and for myriad national and sub-national reporting purposes (for example, European Union Emissions Trading Scheme; EU ETS). As with the other so-called 'Kyoto protocol GHGs', the Intergovernmental Panel on Climate Change (IPCC) provides a methodology for national and sub-national estimation of $N_2O$ emissions, based on the sector from which the emissions arise. The objective of this study was to develop a integrated emission factor to estimate the direct $N_2O$ emission from an agricultural field cultivated with the red pepper, soy bean, spring cabbage, autumn cabbage and potato in 2010~2012. Emission factor of $N_2O$ calculated using accumulated $N_2O$ emission, N fertilization rate, and background $N_2O$ emission over three year experiment was $0.00596{\pm}0.001337kg$ $N_2O-N(N\;kg)^{-1}$. More extensive studies need to be conducted to develop $N_2O$ emission factors for other upland crops in the various regions of Korea because $N_2O$ emission is influenced by many factors including climate characteristics, soil properties, and agricultural practices.