• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.158-161
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• 2006

In this paper, we deal with EMI Analysis on Microstrip with Defected Ground plane. Specially, we investigate reflection, transmission, crosstalk, radiated emission on Microstrip with Defected Ground plane structure. And investigates undesired effects on various defected ground plane such as ground with split, slot, short end and open end gap. To analyze reflection, transmission and crosstalk of microstrip with defected ground plane, we used concept of the microstrip to slot line transition model. Besides, investigate radiated emission using FDTD Commercial tools such as CST MW

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.3142-3147
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• 2008

A simple transient simulation of ground source heat pump system was carried out to investigate the effects of ground thermal conductivity on its performance. The TRNSYS code with a simple water to water heat pump model was used to compare the COP variation of the system. A new ground heat exchanger called by semi-closed loop was proposed and constructed in the real site. The effective thermal conductivity was measured using the test equipment developed by according to the line source model. The simulation results showed that highly efficient thermal conductivity of the grout material could increase the performance of the heat pump system very well. And the new ground heat exchanger showed the increased effective thermal conductivity as the penetration water flow rate(PWFR) was increased. Therefore, the performance improvement of the heat pump system using the proposed ground heat exchanger can be expected.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.58-63
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• 2009

A ground-loop heat exchanger for the ground source heat pump system is the core equipment determining the thermal performance and initial cost of the system. The size and performance of the heat exchanger is highly dependent on the ground thermal properties - the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. Nowadays, precast concrete piles using steel reinforced precast concrete piles - energy piles - are used to reduce the installing cost of the ground-loop heat exchanger. We were carried out some tests to investigate the effects of some parameters such as borehole length, grouting materials and U-tube configuration of the energy piles. 4 concrete piles, each measuring $250mm{\sim}400mm$ in diameter and approx. 10m in length, and rigged with single spiral and 3 U-tube loop of $16mm{\times}2.3mm$ PB piping. The thermal response tests were conducted using a testing device for 4-different ground-loop heat exchangers. During the heating period, the energy piles absorb the heat of 0.89kW to 1.37kW.

• 한국환경복원기술학회지
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• 제2권3호
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• pp.18-24
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• 1999

본 연구는 인공지반의 녹화에 보편적으로 이용되고 있는 자연토양, 개량토양, 인공토양에 따른 식물의 생육상태를 밝히기 위해 몇 가지 토양을 배합조성하고 이에 따른 목본식물(자산홍)의 생장상태를 측정하여 다음과 같은 결론을 얻었다. 먼저 토양종류에 따른 목본식물의 생장인자 간에 상관분석을 실시한 결과 지하부의 생장은 공극량 등이 중요하게 관여하고 있으며, 지상부의 경우는 전질소비가 생장에 중요한 영향요인으로 작용되고 있는 것으로 나타났다. 토양재료중 자연토양(밭흙)은 지상의 생장(수고, 엽수, 엽폭, 절화수)과 지상부의 건물중, 지하부의 건물중 모두 가장 저조한 것으로 나타났다. 인공토양(버미큘라이트)은 지상의 생장(수고, 엽수, 엽폭, 절화수 등)은 좋지 않았으나 상대적으로 지하부의 건물중이 월등히 높았으며 이러한 지하부의 우수한 생육에 기인하여 총건물중도 가장 높게 나타났다. 따라서 인공토양인 버미큘라이트의 경우 지닌 양분이 미약하여 지상의 생육상태는 양호하지 못했으나 통기성 및 투수성 등이 좋아 지하부의 생육에 결정적인 영향을 미친 것으로 판단된다. 밭흙을 주재료로 한 개량토양 중 버미큘라이트와 훈탄을 배합한 처리구는 지상부, 지하부 모두 중간정도의 생장상태를 나타냈다. 부숙톱밥을 혼합한 개량토양의 경우 총건물중은 인공토양(버미큘라이트) 다음으로 높았으며 나머지 수고, 엽수, 엽폭, 절화수 및 지상부의 건물중 등 지상부의 생장상태는 가장 좋은 것으로 나타났다. 특히 유기물 재료 중에서도 훈탄보다는 부숙톱밥이 들어간 배합토에서 생육이 좋은 것으로 나타났다.

• Earthquakes and Structures
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• 제5권2호
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• pp.129-142
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• 2013

Linear and nonlinear time history analyses have been becoming more common in seismic analysis and design of structures with advances in computer technology and earthquake engineering. One of the most important issues for such analyses is the selection of appropriate acceleration time histories and matching these histories to a code design acceleration spectrum. In literature, there are three sources of acceleration time histories: artificial records, synthetic records obtained from seismological models and accelerograms recorded in real earthquakes. Because of the increase of the number of strong ground motion database, using and scaling real earthquake records for seismic analysis has been becoming one of the most popular research issues in earthquake engineering. In general, two methods are used for scaling actual earthquake records: scaling in time domain and frequency domain. The objective of this study is twofold: the first is to discuss and summarize basic methodologies and criteria for selecting and scaling ground motion time histories. The second is to analyze scaling results of time domain method according to ASCE 7-05 and Eurocode 8 (1998-1:2004) criteria. Differences between time domain method and frequency domain method are mentioned briefly. The time domain scaling procedure is utilized to scale the available real records obtained from near fault motions and far fault motions to match the proposed elastic design acceleration spectrum given in the Eurocode 8. Why the time domain method is preferred in this study is stated. The best fitted ground motion time histories are selected and these histories are analyzed according to Eurocode 8 (1998-1:2004) and ASCE 7-05 criteria. Also, characteristics of both near fault ground motions and far fault ground motions are presented by the help of figures. Hence, we can compare the effects of near fault ground motions on structures with far fault ground motions' effects.

• 조명전기설비학회논문지
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• 제15권2호
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• pp.97-104
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• 2001

본 논문에서는 전위강하법에 의한 접지저항 측정시 전위보조전극 위치의 영향에 대하여 기술하였다. 전위강하법에서 접지저항은 이론적으로 전위보조전극을 피측정 접지전극과 전류보조전극이 이루는 일직선상에 위치시킬때 61.8[%]법칙을 적용하여 측정한다. 하지만 측정현장의 사정상 전위보조전극의 위치를 피측정 접지전극과 전류 보조전극이 이루는 일직선과 어느 정도의 각도를 가지도록 시설하여 접지저항을 측정하게 될 경우에 측정오차가 발생하게 되고 보정이 필요하다. 본 연구에서의 측정대상 전극은 길이 2.4 [m]의 봉형 접지전극으로 하였으며, 피측정 접지전극, 전위보조전극, 전류보조전극이 일직선상에 놓이지 않은 상태에서 접지저항을 측정하면 측정값은 항상 (-)의 오차를 나타내었고, 이들 전극이 이루는 각도가 증가함에 따라 측정 오차도 증가하였다.

• Structural Engineering and Mechanics
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• 제65권6호
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• pp.771-784
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• 2018

This study aims to investigate the stochastic response of isolated and non-isolated highway bridges subjected to spatially varying earthquake ground motion model. This model includes wave passage, incoherence and site response effects. The wave passage effect is examined by using various wave velocities. The incoherency effect is investigated by considering the Harichandran and Vanmarcke coherency model. The site response effect is considered by selecting homogeneous firm, medium and soft soil types where the bridge supports are constructed. The ground motion is described by power spectral density function and applied to each support point. Triple concave friction pendulum (TCFP) bearing which is more effective than other seismic isolation systems is used for seismic isolation. To implement seismic isolation procedure, TCFP bearing devices are placed at each of the support points of the deck. In the analysis, the bridge selected is a five-span featuring cast-in-place concrete box girder superstructure supported on reinforced concrete columns. Foundation supported highway bridge is regarded as three regions and compared its different situation in the stochastic analysis. The stochastic analyses results show that spatially varying ground motion has important effects on the stochastic response of the isolated and non-isolated bridges as long span structures.

• 항공우주시스템공학회지
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• 제10권4호
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• pp.11-16
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• 2016

본 논문에서 채널 안내로를 비행하는 가변스팬 날개의 공력특성에 관한 실험연구를 수행하였다. NACA 0012익형을 가진 가변스팬 날개를 제작하였으며 선형서보모터를 사용하여 작동시켰다. 날개의 가로세로비, 지면효과, 날개와 펜스사이의 거리가 날개의 공력특성에 미치는 영향을 조사하였다. 연구결과 지면 및 펜스 모두 항공기 날개의 양력을 증가시켰으며 지면효과와 달리 펜스는 날개의 항력에 큰 영향을 미치지 않았다. 가변스팬 메커니즘이 플랩사용이 제한되는 상황에서 효과적인 고양력 장치로 사용가능할 것으로 판단된다.

• Journal of Ecology and Environment
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• 제35권2호
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• pp.79-89
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• 2012

This study was conducted with the intention of clarifying the effects of land-use types on a species of ground beetle's richness, abundance, and composition; the study focused on urban landscapes. We also selected the potential bioindicators classifying land-use types; eleven sites were selected from an urban landscape in Korea. Overall, land-use types in urban landscapes did not appear to cause significant decrease in species richness or the abundance of total ground beetle assemblage. According to habitat preferences, several land-use types and distances from the forest significantly affected the species richness and abundance, while the open-habitat species were not affected by these variables. Land-use types were classified into two major groups, forest and non-forest areas, based on ground beetle assemblage; several indicators, such as $Dolichus$ $halensis$ $halensis$ and subfamily Carabinae species, were of particular consideration. In conclusion, environmental change by anthropogenic disturbance can cause different effects on ground beetle assemblages, and forest specialists can be negatively affected.

• 한국운동역학회지
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• 제21권1호
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• pp.9-16
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• 2011

The purpose of this study is to analyze the effects of both various shoe types and bare feet on ground reaction force while walking. Ten first-year female university students were selected. A force platform(Kistler, Germany) was used to measure ground reaction force. Six types of shoe were tested: flip flops, canvas shoes, running shoes, elevated forefoot walking shoes, elevated midfoot walking shoes, and five-toed shoes. The control group was barefooted. Only vertical passive/active ground reaction force variables were analyzed. The statistical analysis was carried out using the SAS 9.1.2 package, specifically ANOVA, and Tukey for the post hoc. The five-toed shoe had the highest maximum passive force value; while the running shoe had the lowest. The first active loading rate for running shoes was the highest; meanwhile, bare feet, the five-toed shoe, and the elevated fore foot walking shoe was the lowest. Although barefoot movement or movement in five toed shoes increases impact, it also allows for full movement of the foot. This in turn allows the foot arch to work properly, fully flexing along three arches(transverse, lateral, medial), facilitating braking force and initiating forward movement as the tendons, ligaments, and muscles of the arch flex back into shape. In contrast movement in padded shoes have a tendency to pound their feet into the ground. This pounding action can result in greater foot instability, which would account for the higher loading rates for the first active peak for padded shoes.