• Korean journal of food and cookery science
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• v.9 no.4
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• pp.317-322
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• 1993

Two kinds of simple and interesterfying mixed rapeseed oil were prepared according to add 30%, 50% and 70% of coconut and palm oil, then the physicochemical propecties such as the tedency of oxidation, foaming activity were Investigated. The initial AV and POV of interesterifyung mixed rape-seed oils were higher than those of simple mixed oils, but the tendencies of oxidation were similar. The intial value of IV interesterfied rapeseed oils was added in simple mixed rapeseed oil, Induction period were increased about 2.4~4 times. Induction period of intereterifyng mixed oils added palm ell increased about 2~3.2 times. While the foaming Buantity of interesterifing mixed rapeseed oils with palm oil were lower about 28~40% than those of the simple mixed rapeseed oils.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.72-72
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• 2011

산업의 발달과 건설재료의 개발 및 설계 시공 기술의 급속한 발전으로 더 가볍고 더 긴 경간을 가진 교량이 건설되고 있다. 그러나 교량이 더 길어지고 가벼워질수록 풍하중에 의한 영향은 더욱 크게 받게 되어 여러 종류의 피해를 입게 된다. 이제는 어느 정도 잘 알려진 1940년에 발생한 Tacoma Narrow교의 붕괴사고는 내풍 설계의 필요성을 극단적으로 보여주는 대표적인 예로서 본격적인 내풍 공학 연구에 시발점이 되었다. 현재까지 아직 시공은 되지 않았으나 기본 설계 및 내풍안정성 평가가 완료되 주경간장 3,300m의 Messina교 및 2,800m의 일본해협횡단도로 프로젝트 초장대 현수교(안)의 출현까지 짧은 기간 동안 비약적인 기술 성장을 이루고 있다. 장대교량의 설계시 많은 풍동실험을 거쳐서 내풍안정성이 뛰어난 단면을 찾게 된다. Akashi교의 경우에도 트러스, 싱글박스, 트윈박스 등의 다양한 단면에 대한 풍동실험을 수행한 끝에 최종적으로 트러스 단면을 선택하였다. Great Belt교에서는 싱글박스 단면을 대상으로 다양한 단부 각도에 대한 결과를 바탕으로 최종 단면을 선정하였다. Stonecutter 교에는 트윈박스를 채용하여 기존 싱글박스를 뛰어넘는 도약을 단행하였다. 그리고 Messina교의 경우에는 약 20년에 걸쳐서 설계를 진행해 오면서 점진적으로 단면을 개선하여 최종적으로 트리플박스 단면을 채택하였다. 국내에서도 광양대교의 설계시 싱글박스에서 시작하여 트윈박스의 간격 최적화를 통하여 최종단면을 도출하였다. Akashi교는 최장경간장을 자랑하지만 고전적인 트러스 단면을 사용함으로써 Great Belt교, Stonecutter교, Messina교 등과 같이 혁신적인 단면을 채택한 교량에 비하여 상대적으로 기술적 가치를 인정받지 못하고 있다. 따라서 새로운 내풍 단면의 개발은 교량 설계를 위한 실용적인 측면에서 매우 중요하다. 본 연구에서는 경제적이고 내풍안정성이 우수한 도전적인 현수교 단면을 개발하는데 목적을 두고 있다. 이를 위하여 먼저 교량 계획 단계에 필요한 자료를 제공하기 위하여 기존 강박스 현수교의 제원을 수집하고 그 특성을 분석하여 각종 구조 변수들이 내풍안정성에 미치는 상대적인 영향을 평가하고, 근사적으로 고유진동수를 추정할 수 있는 추정식을 제시하였다. 그 다음으로 초장대 현수교 단면을 개발하기 위하여 다양한 풍동실험을 수행하고 가능한 단면 형상을 제시하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1A
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• pp.9-18
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• 2011

Generally the connection of structural members is assumed as hinge, rigid and semi-rigid connections. The exact tangent stiffness matrix of a semi-rigid frame element is newly derived using the stability functions considering shear deformations. Also, linearized elastic- and geometric-stiffness matrices of shear deformable semi-rigid frame are newly proposed. For the exact stiffness matrix, an accurate displacement field is introduced by equilibrium equation for beam-column under the bending and the axial forces. Also, stability functions considering sway deformation and force-displacement relations with elastic rotational spring on ends are defined. In order to illustrate the accuracy of this study, various numerical examples are presented and compared with other researcher's results. Lastly, shear deformation and semi-rigid effects on buckling behaviors of structure are parametrically investigated.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.127-134
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• 2004

Rammed Aggregate Pier (RAP) has extensive applicability as for a foundation of structures. In this study, bearing capacity of the reinforced ground by RAP and the failure behavior of RAP are investigated through experiments. RAPs with diameters of 45, 60, 70 mm were installed in sand, of which relative densities are 60, 70, 90%. Then, two columns of pressure gauges, near the RAPs and one diameter off from the center of piers, are installed 5, 10, 15, 20, 25, 30 cm from the surface of the ground. The test results show that maximum lateral earth pressure is observed near 5∼10 cm (1.0∼2.0D) from the surface, which indicates the occurrence of bulging failure type. In addition, deformation of RAP in radial direction increases with lower relative density of the ground. Furthermore, lateral stress distribution decreases with depth.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.8
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• pp.687-693
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• 2014

In this study, the performance characteristics of a polymer electrolyte membrane fuel cell (PEMFC) were investigated at low operating temperatures under steady-state and dynamic conditions. The performance of the PEMFC was analyzed according to the external humidifying rate and air stoichiometry. The ohmic resistance was also investigated using EIS tests. At the operating temperature of $35^{\circ}C$, voltage fluctuation occurred to a greater degree compared to that at $45^{\circ}C$. Therefore, it was found that the air stoichiometry should be higher than 2.5 for the stable operation of the fuel cell. In addition, the relative humidity of the reactant gases should be higher than 60 to reduce the ohmic resistance.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1841-1844
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• 2009

일반 하천에서의 유량측정 방법은 하천 조건에 따라 다르다. 전통적인 방법으로는 구조물에 의한 방법, 유속계 측정에 의한 유속-면적법, 부자에 의한 방법, 그리고 희석법 등이 있다. 그러나 이러한 방법들은 측정 위험성을 가지고 있다. 홍수시 발생되는 고유속과 심한 난류, 거대한 부유물질들은 하천 접근에 어려움을 가져오고, 측정 기기의 파손 위험성뿐만 아니라 인명피해까지 발생시킬 가능성이 있다. 최근 기존 방법들의 문제점을 해결하기 위하여 음파, 초음파, 레이더 등을 이용한 유량 측정 방법과 장비들이 개발되었다. 본 연구에서 사용한 레이더 유속계는 하천의 표면유속을 측정하는 비접촉식 센서로 홍수기 전 미리 유속 측정 단면 측량을 실시한다면 홍수시에도 비교적 신속하고 안전하게 유속을 측정할 수 있다. 따라서 본 연구에서는 레이더 유속계를 충청북도 괴산군 달천에 위치한 수전교에 설치하여 괴산댐 방류량 및 동시유량 측정 성과와 비교하였다. 2007년 7월부터 2008년 8월까지 $36m^3/s\;\sim\;821m^3/s$의 사상에서 총 10회 측정한 결과, 레이더 유속계를 사용하여 측정한 유량의 상대오차는 댐방류량 대비 -3.3% $\sim$ 27.5%로 나타나 평균11.8%의 상대오차를 보였다. 레이더 유속계 측정과 동시에 실시한 유속-면적법 측정, ADCP법 측정의 상대오차는 각각 평균 5.7%, 6.5%로 나타난 것과 비교한다면 다소 높은 오차를 보였다. 그러나 측정 시간의 경우 수위에 따라 다소 차이는 있지만 레이더 유속계를 이용하면 30분 정도의 시간이 소요되었으며, 유속면적법은 1시간 이상, ADCP법은 40분의 시간이 소요되었다. 이와 같이 레이더 유속계는 다른 방법에 비해 정확성은 다소 떨어지지만 측정 속도와 안정성 면에서는 우수하다고 판단된다. 문제점으로 지적되는 정확도 측면의 경우 레이더 유속계로 측정되는 표면유 속과 평균 유속 사이의 보정계수 문제를 보완한다면 보다 정확한 측정이 가능할 것으로 판단된다.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.6
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• pp.780-787
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• 2012

In general, the ocean wave vibration power generator consists of buoy, vibration system and linear generation system. It maximized energy efficiency by using resonance phenomenon that turned to the natural frequency of vibration system and frequency of ocean wave energy. But it is difficult to obtain efficiently energy from ocean wave because the frequency of ocean wave changes from moment to moment. In this paper, we study the buoy and vibration system of ocean wave power generator to solve these problem. Firstly, we designed the buoy that gives rise to resonance between ocean wave and buoy. Secondly, we designed vibration system that is occurred to resonance between buoy and vibration system. And then the relative velocity between the buoy and magnetic of ocean wave vibration generator increases and the relative displacement between buoy and ocean wave decreases at the same time. As a result, the method which is proposed in this paper has merits not only securing its stability from harsh ocean wave environment but also obtaining more kinetic energy from ever-changing ocean wave.

• International Area Studies Review
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• v.14 no.1
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• pp.185-202
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• 2010

While it is often assumed that a country's trade balance will improve in the long-run if its currency is allowed to depreciate, this is not necessarily the case for specific industry. This paper is to examine the long-run relationships between trade balance and real exchange rate using bilateral data of SITC 10 Industry Classification for Korea vis-${\grave{a}}$-vis her trading partners Indonesia, India, China, Japan on a quarterly basis over the period of 1999Q1 to 2008Q4. I applied the recent panel cointegration technique to reduce the small sample problems and improving power performance of the relevant estimation and inference procedures. The results reveal evidence of the Marshall-Lerner Condition in Indonesia 2 industries, India 5 industries, Japanese 4 industries, Chinese 6 industries. Whole group's cointegration statistic of India, China, Japan was supported Marshall-Lerner Condition but Indonesia was rejected.

• The Journal of Engineering Geology
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• v.33 no.2
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• pp.229-240
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• 2023

Instruments are installed in soft ground improvement projects to manage economic and safe construction. When analyzing data, the amount of settlement data over time can be used to understand the overall ground settlement behavior, but it is difficult to analyze the interrelatedness between measurement points. Therefore, to analyze the relative compressive settlement behavior between measurement points, the settlement amount and velocity were processed and defined as the mean settlement difference index (AS_i,j) and the slope difference index (SDI_i,j). Plotted in the mean settlement difference index - slope difference index (AS_i,j-SDI_i,j) coordinate system. As a result of the analysis of the relative compaction subsidence behavior between the measuring points, the relationship between the measuring points in the average subsidence difference index - slope difference index coordinate system moved to area 1 as the compaction was completed. By continuously plotting the movement path of the observation point in the corresponding coordinate system, the relative settlement behavior between the measurement points was analyzed, and it was possible to check whether the settlement behavior of the two measurement points was stable or unstable depending on the direction of the path.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.177-184
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• 2012

Purpose: In this study, the effect of the eye movement direction on visual function related to accommodation was investigated when playing computer games for a certain period of time. Methods: Total 60 subjects in 20s who had the visual acuity of 1.0 or higher without any ocular disease and accommodative dysfunction were asked to play computer games separately in horizontal and vertical directions for 40 and 90 minutes and then measured their accommodative amplitude, accommodative facility, accommodative lag and relative accommodations. Thevisual function when not doing the computer game was regarded as a control value, and further compared and analyzed. Results: The accommodative amplitude, accommodative facility, accommodative lag and relative accommodations showed the tendency of decrease after the computer game for 40 minutes, and more reduced values of the visual functions were shown when the computer game extended up to 90 minutes except positive relative accommodation. Positive relative accommodation had a tendency to increase slightly after the computer game for 90 minutes. Meanwhile, the change of the visual functions was primarily influenced by the eye movement in horizontal direction rather than by the eye movement in vertical direction during computer game when analyzed by the direction of eye movement. Conclusions: Over all accommodative functions tended to decrease with the extended VDT working time by computer game, and the frequent eye movement in horizontal direction during VDT tasks could be the main cause of eyestrain since the eye movement in horizontal direction rather than vertical direction significantly affected the change of accommodative function.