• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1318-1323
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• 2009

In recent years, dramatic advances in information technology have motivated the construction industry to improve its productivity. Computer-based information technology includes Computer-Aided Design (CAD), Computer-Aided Engineering (CAE), Computer-Aided Manufacturing (CAM), Enterprise Resource Planning (ERP), Digital Mock-Up (DMU) and Product Data Management (PDM). Most construction industries are trying to apply these technologies for quality improvement, reduction of construction time and cost. PDM is very useful for managing data and process related to product design and manufacturing. PDM system has various functions such as drawing and engineering document management, product structure and structure modification management, part classification management, workflow management, and project management. In this paper, PDM system was applied to the design of steel-concrete composite girder bridge. To make a practical guidance for PDM implementation to bridge design, the procedure for its implementation was presented. Consequently, this paper could be useful to enhance the efficiency of bridge design.

• 대한교통학회지
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• 제27권3호
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• pp.91-102
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• 2009

도로설계 안전성을 평가하기 위해서는 도로의 설계 요소변화가 사고에 미치는 영향을 예측할 수 있어야 한다. 이를 위해 본 연구에서는 통계적 방법, 사고이력, 전문가의 판단, 그리고 기존문헌고찰 등 다양한 방법을 통하여, 설계요소의 특징과 사고율 및 사고빈도의 관계를 반영할 수 있는 AMF(Accident Modification Factor)를 개발하고자 하였다. 본 연구에서는 AMF를 좌회전전용차로, 우회전전용차로, 시거, 교차각 등의 항목을 대상으로 개발하였다. 개발된 AMF를 적용한 경우의 사고 예측값, 사고예측모형을 통한 예측값을 실제 사고데이터와 비교분석함으로써 적정성을 검토하였다. 분석결과, AMF를 적용한 예측값이 사고예측모형을 통한 예측 값보다 예측력이 우수함을 확인할 수 있었다. 이러한 결과는 사고를 예측함으로써 도로설계 안전성을 평가하는 알고리즘에 있어 AMF가 도로의 설계요소의 특성을 보다 효과적으로 반영하며, 지방부 교차로에서 각각의 해당요소가 사고에 미치는 영향을 판단할 수 있는 지표가 될 수 있음을 의미한다.

• Wind and Structures
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• 제32권3호
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• pp.227-238
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• 2021

This study analyzed the pressure patterns and local pressure of tall buildings with corner modifications (recessed and chamfered corner) using wind tunnel tests and proper orthogonal decomposition (POD). POD can distinguish pressure patterns by POD mode and more dominant pressure patterns can be found according to the order of POD modes. Results show that both recessed and chamfered corners effectively reduced wind-induced responses. Additionally, unique effects were observed depending on the ratio of corner modification. Tall building models with recessed corners showed fluctuations in the approaching wind flow in the first POD mode and vortex shedding effects in the second POD mode. With large corner modification, energy distribution became small in the first POD mode, which shows that the effect of the first POD mode reduced. Among building models with chamfered corners, vortex shedding effects appeared in the first POD mode, except for the model with the highest ratio of corner modifications. The POD confirmed that both recessed and chamfered corners play a role in reducing vortex shedding effects, and the normalized power spectral density peak value of modes showing vortex shedding was smaller than that of the building model with a square section. Vortex shedding effects were observed on the front corner surfaces resulting from corner modification, as with the side surface. For buildings with recessed corners, the local pressure on corner surfaces was larger than that of side surfaces. Moreover, the average wind pressure was effectively reduced to 88.42% and 92.40% in RE1 on the windward surface and CH1 on the side surface, respectively.

• 항공우주시스템공학회지
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• 제17권4호
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• pp.87-94
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• 2023

본 논문은 항공기의 성능개량에 필수 수반되는 신규 및 변경 장비 장착부에 기체구조물 개조 및 장착설계를 수행한 연구이다. 항공기 외부에 장착되는 대표적인 성능개량 장비로는 안테나, 레이더, 전자광학/적외선 표적지시장치(EO/IR) 및 자체방어체계 장비 등이 있으며, 운용을 위해서 기본항공기의 구조보강, 개조 및 장착설계가 수행된다. 항공기 내부에는 사용자 운용 요구도에 맞게 콘솔과 랙 구조물이 개조 또는 추가된다. 또한 성능개량을 위해 교체 및 추가되는 장비의 장착설계와 이에 따른 내부 냉각을 위한 환경제어계통 구성품 개조가 수반된다. 성능개량 항공기의 구조건전성, 운용성 및 정비성이 확보된 기체구조물의 상세설계로 감항 적합성이 검증된 엔지니어링 과정과 사례를 제시하였다.

• 상하수도학회지
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• 제37권4호
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• pp.177-186
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• 2023

Perfluorooctanoic acid(PFOA) was one of widely used per- and poly substances(PFAS) in the industrial field and its concentration in the surface and groundwater was found with relatively high concentration compared to other PFAS. Since various processes have been introduced to remove the PFOA, adsorption using GAC is well known as a useful and effective process in water and wastewater treatment. Surface modification for GAC was carried out using Cu and Fe to enhance the adsorption capacity and four different adsorbents, such as GAC-Cu, GAC-Fe, GAC-Cu(OH)₂, GAC-Fe(OH)₃ were prepared and compared with GAC. According to SEM-EDS, the increase of Cu or Fe was confirmed after surface modification and higher weight was observed for Cu and Fe hydroxide(GAC-Cu(OH)₂ and GAC-Fe(OH)₃, respectively). BET analysis showed that the surface modification reduced specific surface area and total pore volumes. The highest removal efficiency(71.4%) was obtained in GAC-Cu which is improved by 17.9% whereas the use of Fe showed lower removal efficiency compared to GAC. PFOA removal was decreased with increase of solution pH indicating electrostatic interaction governs at low pH and its effect was decreased when the point of zero charges(pzc) was negatively increased with an increase of pH. The enhanced removal of PFOA was clearly observed in solution pH 7, confirming the Cu in the surface of GAC plays a role on the PFOA adsorption. The maximum uptake was calculated as 257 and 345 ㎍/g for GAC and GAC-Cu using Langmuir isotherm. 40% and 80% of removal were accomplished within 1 h and 48 h. According to R², only the linear pseudo-second-order(pso) kinetic model showed 0.98 whereas the others obtained less than 0.870.

• 생물환경조절학회지
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• 제2권2호
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• pp.126-135
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• 1993

Recently, the characteristic of plant production systems in Korea has been changed with the strong trends of integration and large scale, using environmental control techniques. To satisfy this change successfully, first of all, the environmental prediction inside the system must be preceded. While many environmental prediction models for plant production system were developed by many persons, each model cannot be applied to the every situation without the perfect understanding of source codes and the technical modification. The purpose of this study is building the environmental prediction model to predict and evaluate the environment inside the system numerically, and also developing the multipurpose program available for practical design. The model consisted of the basic system model, the cultivation related model and the environmental control related model. The contents of each model are as follows : the basic system model is dealing with thermal and light environments, soil environment and ventilation : the cultivation related model with soil and hydroponic cultures ; and the environmental control related model with thermal curtain and heat exchanging system. The environmental prediction model was developed using a common simulation program, PCSMP, so that it could be easily understood and modified by anyone. Finally, the model was executed and verified through comparison between simulated and measured results for soil culture, and both results showed good agreements.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2004년도 International Conference Global Environmental Problems and their Health Consequences
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• pp.178-181
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• 2004

Di-n-butyl phthalate (DBP) is used extensively in the plastic industry and has been known as an environmental hormone (endocrine disruptor). Present study was undertaken to examine whether DBP can induce oxidative stress in mice. In this study, oxidative stress was measured in terms of the modification of lipid peroxidation and gamma-glutamyltranspeptidase (${\gamma}-GT$) activity. The activity of ${\gamma}-GT$, the level of lipid peroxidation and serum toxicity index were measured in male ICR mice after treatment with DBP (5 g/kg, po). Administration of DBP was found to significantly increase the level of lipid peroxidation approximately 2 fold in liver. The activity of ${\gamma}-GT$ in the liver of DBP-exposed animals was also increased approximately 2.5 fold. However, DBP did not alter the parameters for hepatotoxicity and nephrotoxicity such as alanine aminotransferase (ALT), aspartate aminotransferase (AST) and creatinine. These results indicate that DBP can induce oxidative stress in mice. The ${\gamma}-GT$ activity is considered to be increased as one of the adaptive defense mechanisms to oxidative stress induced by DBP.

• Environmental Engineering Research
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• 제14권3호
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• pp.153-157
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• 2009

Arsenic at abandoned mine sites has adversely affected human health in Korea. In this study, the feasibility of using cationic surfactant-modified activated carbon (MAC) to remove As(V) was evaluated in terms of adsorption kinetics, adsorption isotherms, and column experiments. The adsorption of As(V) onto MAC was satisfactorily simulated by the pseudo-second-order kinetics model and Langmuir isotherm model. In column experiments, the breakthrough point of AC was 28 bed volumes (BV), while that of MAC increased to 300 BV. The modification of AC using cationic surfactant increased the sorption rate and sorption capacity with regard to As(V). As a result, MAC is a promising adsorbent for treating As(V) in aqueous streams.

• 대한환경공학회지
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• 제27권1호
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• pp.109-114
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• 2005

본 연구에서는 기상용 제오카본을 수처리에 적합하도록 염산으로 표면 개질 하였으며, 개질된 제오카본을 이용하여 단일 공정을 통한 암모니아성 질소와 질산성 질소 동시 제거 가능성을 평가하고자 하였다. 제오카본과 비교하여 표면 개질 제오카본의 강도가 62% 정도 증가하였으며, 암모니아성 질소와 질산성 질소 및 총질소 제거율이 약 2배 증가하였다. 또한 암모니아성 질소와 질산성 질소 제거 효율은 pH 및 온도 변화에 거의 영향을 받지 않았다. 따라서 수중에 존재하는 암모니아성 질소와 질산성 질소의 동시 제거가 매우 효과적으로 이루어질 수 있었으며, 본 연구 결과를 토대로 암모니아성 질소와 질산성 질소를 동시 제거할 수 있는 단일 공정 설계를 위한 기본 데이터 제시가 가능하였다.

• 상하수도학회지
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• 제32권5호
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• pp.399-409
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• 2018

Prussian blue is known as a superior material for selective adsorption of radioactive cesium ions; however, the separation of Prussian blue from aqueous suspension, due to particle size of around several tens of nanometers, is a hurdle that must be overcome. Therefore, this study aims to develop granule type adsorbent material containing Prussian blue in order to selectively adsorb and remove radioactive cesium in water. The surface of granular activated carbon was grafted using a covalent organic polymer (COP-19) in order to enhance Prussian blue immobilization. To maximize the degree of immobilization and minimize subsequent detachment of Prussian blue, several immobilization pathways were evaluated. As a result, the highest cesium adsorption performance was achieved when Prussian blue was synthesized in-situ without solid-liquid separation step during synthesis. The sample obtained under optimal conditions was further analyzed by scanning electron microscope-energy dispersive spectrometry, and it was confirmed that Prussian blue, which is about 9.7% of the total weight, was fixed on the surface of the activated carbon; this level of fixing represented a two-fold improvement compared to before COP-19 modification. In addition, an elution test was carried out to evaluate the stability of Prussian blue. Leaching of Prussian blue and cesium decreased by 1/2 and 1/3, respectively, compared to those levels before modification, showing increased stability due to COP-19 grafting. The Prussian blue based adsorbent material developed in this study is expected to be useful as a decontamination material to mitigate the release of radioactive materials.