• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2061-2066
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• 2007

Recently, ultra-lightweight materials with open, periodic cell structures take much attention owing to its potential for multi-functionality such as load bearing, thermal dissipation, and actuation. This paper presents experimental results on the hydraulic and heat transfer characteristics for the Wire-woven Bulk Kagome(WBK) composed of aluminum 1100 wires. The overall pressure drop and heat transfer of the WBK specimen have been experimentally investigated under forced air convection condition. The pressure loss and heat transfer performance of the aluminum WBK are compared with other heat dissipation media. It was shown that heat transfer depended on relative density and surface area density. Comparison with metal foams and other heat dissipation media such as packed beds, lattice frame materials, louvered fins, and other materials suggests that the aluminum WBK competes favorably with the best available heat dissipation media in heat transfer performance.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.3 s.73
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• pp.233-238
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• 2006

In this paper, mixed mode magneto-rheological(MR) damper, which is applicable for vibration control of a small scale multi-story structure, is devised. First, the schematic configurations of the shear, flow, and mixed mode MR dampers are described with design constraints and then the analytical models to predict the field-dependent damping forces are derived for each type. Second, an appropriate size of the mixed mode MR damper is manufactured and its field-dependent damping characteristics are evaluated in time domain. Finally, the performance of the manufactured MR damper which is semi-actively applied to a small scale building excited by earthquake load, is numerically evaluated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.1
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• pp.15-22
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• 2008

Recently, ultra-lightweight materials with open, periodic cell structures take much attention owing to its potential for multi-functionality such as load bearing, thermal dissipation, and actuation. This paper presents experimental results on the fluid flow and heat transfer characteristics for the Wire-woven Bulk Kagome (WBK) composed of aluminum 1100 wires. The overall pressure drop and heat transfer of the WBK specimen was experimentally investigated under forced air convection condition. The pressure loss and heat transfer performance of the aluminum WBK were compared with other heat dissipation media. It was shown that heat transfer characteristics depended on relative density and surface area density. Comparison with metal foams and other heat dissipation media such as packed beds, lattice frame materials, louvered fins, and others suggests that the aluminum WBK competes favorably with the best available heat dissipation media in heat transfer performance.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.2
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• pp.63-81
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• 2021

In this study, we investigated the tide-induced flow patterns near the ocean outfall of the Jeju and Bomok Wastewater Treatment Plants (WTP) in Jeju Island by using measurements of Acoustic Doppler Current Meter (ADCP) and a numerical experiment with inserting passive tracer into a regional ocean model. In late spring of 2018, the ADCP measurements showed that tidal currents dominate the flow patterns as compared to the non-tidal components in the outfall regions. According to harmonic analysis, the dominant type of tides is mixed of diurnal and semi-diurnal but predominantly semidiurnal, showing stronger oscillations in the Jeju WTP than those in the Bomok WTP. The tidal currents oscillate parallel to the isobath in both regions, but the rotating direction is different each other: an anti-clockwise direction in the Jeju WTP and a clockwise in the Bomok WTP. Of particular interest is the finding that the residual current mainly flows toward the coastline across the isobath, especially at the outfall of the Bomok WTP. Our model successfully captures the features of tidal currents observed near the outfall in both regions and indicates possibly high persistent pollutant accumulation along the coasts of Bomok.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.2
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• pp.91-98
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• 2009

The long-term water-quality change of Asan Bay by the influx of polluted disposal water was predicted through a simulation with an Eco-hydrodynamic model. Eco-hydrodynamic model is composed of a multi-level hydrodynamic model to simulate the water flow and an ecosystem model to simulate water quality. The water quality simulation revealed that the COD(Chemical Oxygen Demand), dissolved inorganic nitrogen(DIN) and dissolved inorganic phosphorus(DIP) are increased at 5 stations for the subsequent 6 months after the influx of the effluent. COD, DIN and DIP showed gradual decreases in concentration during the period of one to two years after the increase of last 6 months and reached steady state for next three to ten years. Concentration levels of COD, DIN, and DIP showed the increase by the ranges of $11{\sim}67%$, $10{\sim}67%$, and $0.5{\sim}7%$, respectively, which represents that the COD and DIN are the most prevalent pollutants among substances in the effluent through the sewage treatment plant. The current water quality of Asan Bay based on the observed COD, TN and TP concentrations ranks into the class II of the Korean standards for marine water quality but the water quality would deteriorate into class III in case that the disposal water by the sewage plant is discharged into the Bay.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.420-420
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• 2011

도시지역의 내수침수피해는 거의 매년 발생하고 있으며, 반지하와 같은 거주공간이 매우 취약한 상태이다. 특히 최근에는 지하철, 지하상가 등이 대규모 개발되고 복합네트워크화 되어 지하공간의 침수대책과 대피방안 마련이 시급한 상황이다. 일본의 경우 2000년 토카이 호우피해 후 통합유출해석 모형을 개발하였으며, 1999년 및 2003년 후쿠오카 침수피해 발생 후 특정도시하천침수피해대책법을 제정, 1999 후쿠오카, 2004년 하마마츠, 2008년 카누마 피해 후 일본 방재연구소에서는 실시간 1차원 지표범람모형과 모니터링을 통한 실시간 내수침수지도를 개발하였다. 특히 지하공간에 대해서는 "지하공간에 유입하는 범람수가 계단상 보행자게에 주는 위험성에 관한 연구" 등 실험을 바탕으로 각종 지하공간 침수대책 매뉴얼 및 지하시설의 침수시 피난확보계획 지침, 지하공간 침수대책 가이드라인 등 인명피해를 줄이고자하는 노력이 계속되어 오고 있다. 우리나라는 2006년 경기도 고양시 3호선 정발산역이 침수되었으며, 2010년 서울시 지하철 2호선 사당역 및 4호선이 침수되는 등의 지하철 침수피해와 2010년 서울시 광화문 지하상가, 인천시 부평구 우림라이온스 벨리, 우남플라자, 계양구 농협하나로마트, 서원아파트 등의 지하상가와 지하다층의 침수피해가 발생하였다. 특히 2006년 3호선 정발산역 침수는 17시간이나 지하철이 불통되었고 이로 인하여 심각한 교통 체증이 유발 되었다. 본 연구에서는 2010년 집중호우로 인한 서울, 인천지역의 지하공간 침수피해를 중심으로 최근 10년간 지하공간 침수피해사례로부터 대표적인 침수피해 원인 및 특성을 정리하였으며, 그 결과 지하공간 침수의 주요원인은 지상공간의 침수류가 지하공간으로 유입하고, 지하공간의 배수설비 용량부족, 지하공간으로의 유입을 방지하기위한 방지턱, 차수판, 침수시 비상전원 공급, 침수시 지하공간 대피 매뉴얼의 부재 등 다양한 원인이 있는 것으로 나타났다. 특히, 소방방재청에서 고시한 '지하공간 침수방지를 위한 수방기준'에 지하공간 침수 방지를 위한 각종 시설의 설치 및 대피 경로지정 등에 대한 기준이 마련되어 있으나, 지하공간 중 유동인구가 가장 많은 지하철역에서 조차 침수에 대한 행동매뉴얼이나 대피에 대한 가이드라인이 마련되지 않은 것으로 나타났다. 따라서, 지하공간 침수를 방지하기 위하여 센서를 이용한 자동 차수판과 경보기 설치, 지하공간의 사람들이 안전한 대피로를 찾을 수 있도록 지상공간 및 지하공간 출입구를 모니터링 할 수 있는 CCTV의 설치, Dry Area를 두어 비상대피 할 수 있는 공간의 마련 등 시설적인 부분에 대하여 '지하공간 침수방지를 위한 수방기준'을 더욱 강화할 필요가 있으며, 지상공간의 침수 상황을 고려한 지하공간의 대피매뉴얼 또는 가이드라인 등의 수립이 필요하다. 또한 이와 더불어 재산 및 인명피해를 더욱 효율적으로 줄일 수 있도록 실시간 예 경보를 위한 침수해석 모형의 개발이 시급하다.

• Journal of The Korean Association For Science Education
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• v.41 no.3
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• pp.267-281
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• 2021

The shift in the perspective on learning as participation draws attention to learners' identity work. This manuscript foregrounds the ongoing and fluid processes of identity, and focuses on the structure surrounding learners where identity work occurs and the expression of individual agency. From the perspective of learning as participation, we introduce Holland et al. (1998) identity-in-practice theory, as the theoretical lens that dialectically describes structure, agency and identity. The concepts representing this theory are 'figured world', 'positionality' and 'authoring self'. The figured world is a web of meaning encompassing the continuous construct/reconstruct through human actions and also exerts as the social force that shapes human actions. 'Positionality' on the other hand, means an understanding of one's social position in the world. The notion of 'authoring self', is a dimension that synthesizes the above two concepts, which describes the improvisation of one's self through the orchestration and collaboration of various social voices. Next, we analyzed and described various cases of this theory that we found within the scope of science education. However, due to the nature of this theory, which takes a sociocultural approach, international research studies cannot be simply applied to the Korean context. Therefore, we sought to expand the applicability of this theory as a methodological tool, by discussing the directions in which this theory can be used in a domestic context. It is intended that the introduction of this theory, which emphasizes multi-layered, continuous and cumulative identity work, will be used as a resource to further expand the horizon of science education reform that is required for the times.

• Korean Journal of Agricultural Science
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• v.36 no.1
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• pp.73-85
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• 2009

An investigation was conducted to get the basic data for establishing structural safety and environmental management of tomato greenhouses in Chungnam region. The contents of the investigation consisted of actual state of greenhouse structures and environmental control facilities. Most of greenhouses were arch type single-span plastic houses and they had too low height for growing tomatoes. Frameworks of multi-span greenhouses were suitable, but those of single-span were mostly insufficient. Every greenhouse had thermal curtain movable or covering fixed inside the greenhouse for energy saving, and heating facilities were mostly warm air heater. Irrigation facilities were mostly drip tube and controlled by manual operation or timer. Almost all of the greenhouses didn't install high level of environmental control facilities such as ventilator, air circulation fan, $CO_2$ fertilizer, insect screen, supplemental light, and cooling device.