Earticle

This study shows an application method of Micro Grid integrating Solar Energy Seasonal Storage (SESS) based on the analysis of time-variant load characteristics of electric railway. Micro Grid includes various renewable energy generation plants as like wind farm, photovoltaic, small hydro, fuel cell, etc. and some energy storage systems to meet the balance between generation production and demand. The essential concept of this paper is the connection and integration between electric railway and Micro Grid including SESS which is able to control power system frequency. This new concept for power system stabilization would be tested in an independent Micro Grid site and some detail application methods would be evaluated for the commercialization.

Nowdays, adjacent loading bringing enormous harm to the existing bridge in engineering construction. In this paper, the influencing mechanism of adjacent loading to pier and Law of displacement of pier is researched through living examples， and the safe influence area has been defined. Research shows that: the main damages to piers is caused by the side loading; lateral displacement index of pier top surface is more conservative than the pier additional stress index; it is secure when the distance of adjacent load is 0.5 times of the height of accumulation or 6m, otherwise it would be very scary, and the monitoring measure is necessary.

현재 우리나라에서 보유한 골재자원은 개발수요증가 및 건설투자확대 등으로 고갈이 예상되고 있으며, 정부에서는 향후 골재자원의원활한 공급을 위해 다양한 해결책을 모색하고 있다. 순환골재는 폐콘크리트에서 추출한 골재로 일반골재에 비해 품질이 낮으나, 전처리, 혼화재 적용 등을 통해 일반콘크리트와 유사한 품질을 유도할 수 있는 것으로 알려져 있다. 순환골재 활용성을 극대화할 수 있는 방안은보도블럭, 호안블럭 등 콘크리트 2차 제품에 적용하는 것으로 예상되므로 본 연구에서는 일반골재콘크리트 호안블럭과 유사한 품질을 나타낼 수 있는 순환골재콘크리트 호안블럭의 생산가능성을 분석하였다. 이를 위해 순환골재 및 준조강시멘트의 적용량과 증기양생이력을콘크리트 시험변수로 설정하였으며, 호안블럭 시험에서는 최적의 순환골재콘크리트와 GFRP 보강근 적용에 따른 하중저항성능을 평가하였다. 실험결과, 준조강시멘트와 순환골재를 혼입한 콘크리트는 양생온도 및 지속시간의 변화에도 탈형강도를 만족하였다. 재령 28일강도에서는 증기양생이력에 따라 압축강도의 증감이 확인되었으며, 특히 시멘트량을 감소시킨 변수도 증기양생이력의 조절을 통해 일반콘크리트와 동등한 성능이 발현되었다. 순환골재콘크리트 호안블럭의 재하시험결과, 보강비에 따라 다르나 일반 호안블럭과 유사한 성능을 나타내었다. 따라서 순환골재콘크리트의 낮은 품질특성은 배합 및 양생방법의 조절과 적정 보강재 적용을 통해 보완이 가능할 것으로 판단된다.

Aggregate resources in Korea are expected to run out owing to an increase in development demand and construction investment. Recycled concrete aggregates (RCA), extracted from waste concrete, have a lower quality than natural aggregates. However, RCA can produce concrete similar in quality to the normal concrete by aggregate pretreatment, use of admixtures, and quality control. RCA are most suitable for use in precast concrete products such as sidewalk blocks and revetment blocks. Herein, the feasibility of producing revetment blocks using recycled aggregate concrete (RAC), similar in quality to normal concrete, was analyzed. The amount of RCA was varied, and moderate high early strength cement and steam curing were used to produce the concrete test blocks. In the block test, the load resistance characteristics of the blocks were evaluated to determine optimal RAC and glass fiber reinforced polymer (GFRP) rebar compositions. Thus, the variable that reduced the cement content was determined at the same level as that of natural aggregate concrete by the control of steam curing. In the concrete block test, although this depends on the reinforcement ratio, the RAC block exhibited the same or better performance than a normal concrete block. Therefore, the low quality of RCA in RAC is no longer a problem when concrete mixing and curing are controlled and appropriate reinforcement is used.

In this study, the effect of upper die type on the load characteristics of lower die and the wasted material was studied numerically. The different shapes(A-type, B-type, and C-type) of upper die were applied. Also finite element analysis method was applied for the analysis in each stage. The half of X, Y plane was analyzed due to the symmetrical shape in order to reduce the analysis time and be accurate results. The coefficient of friction was set to oil_cold conditions as refer to the system library. It was revealed that principal stress was the order in A, C, and B. A and B type have the highest value in 4 stage, and C type shows the highest value in 3 stage. In addition, Von mises stress were higher in order A, B, and C. A and B type have the highest in 4 stage, and C type shows to have about the same value in the 2 - 5 stage. The load was generally higher than C type. The load of C type was reduced in YY-direction at each stage without 2, 5, 6 stage.

본 연구는 환경부 비점오염 관리지역으로 지정된 임하호 유역을 대상으로 강우시 비점오염물질의 유출특성을 분석하고 효율적인 임하호내 비점오염물질 유입 저감부하 기초자료를 제시하였다. 미세토사의 다량 유실로 인한 하천의 SS 부하와 TP 부하의 상관성을 분석하여 주로 농경지에서 유실된 미세토사가 탁수 장기화와 인의 유출을 유발하고 호내 장기체류의 원인이 됨을 알 수 있었다. 비점 오염물질 유출 저감을 위하여 유역 내 토사유실 취약 공간 분포 분석을 통하여SS 유출의 원인이 되는 지점을 도출하고 하천 별 대안을 제시하였다. 오염부하 민감 지역을 밝혀 유역의 효율적인 비점오염물질 유출 저감을 위한 유역 관리 기초자료를 제공하였다.

This study aimed at evaluating nonpoint source pollution load and determining effective load mitigation way for Imha watershed designated as a Nonpoint Source Pollution Management Area by Ministry of Environment. The correlativity between the load of SS and that of TP explained that soil loss, mainly from agricultural area, caused turbid water withTP run off during rainfall event. The spatial analysis of soil loss vulnerability revealed the source and mitigation alternatives of SS load, leading to turbid water and nonpoint source pollution at Imha lake. These results introduced effective tool for watershed management to mitigate nonpoint source pollution load.

본 연구는 근대 건축 구조물을 기술사적인 면에서 목조 지붕틀구조의 유형분류에 따른 특성에만 그치지 않고, 부재의 역학적인 특성을 분석하여 당시 서양식 건축구조 기술의 도입에 따른 절충식 지붕틀구조의 하중저항 특성을 평가해 보고자 하였다. 건축구조 기술은 시대의 요구에 맞게 변화를 지속하고, 기술의 변화는 이전의 기술을 발판으로 연속적으로 전개된다. 근대이후 공학적인 기술의 발달로 이전의 경험에 의해 이루어지던 구조체계에 서양의 합리적 구조가 도입되기 시작했다. 특히 서양의 트러스 구조의 장점을 접목한 절충식 지붕구조는 기존 전통적인 목구조 수법에 새로운 서양식 기술이 유입・절충되어가는 과도기 상황을 보여주는 중요한 기술사적 가치를 가진다.

This study analyzed the mechanical properties of the members on the technical historical side of modern buildings. At the time attempted to evaluate the load resistance characteristics of the eclectic roof frame structure by introducing Western style building structural technology. Architectural structure technology continues to change so as to meet the demands of the times. Changes in technology will be deployed to the scaffold on a continual basis with the previous technology. Since the modernization, the rational structure of the Western began to introduce into the structure system established by the development experience of engineering technology. Especially the eclectic roof structure combining the advantages of the Western truss structure shows the state of the transition period when new Western style technology negotiates with the traditional wood structure construction method and has an important value of technology history.

본 연구는 시설원예단지에서 배출되는 배액 내 포함된 영양물질의 부하량을 평가하여 양액 재이용방안 및 수처리장 도입 설계 등에 활용하고자 하였다. 수경재배 대표 재배 작물을 토마토, 파프리카, 오이, 딸기로 선정하여 총 80 샘플 을 수질분석하였다. 분석결과 N, P, K+, Na+, Mg2+, Ca2+, Si4 +, HCO3 -, Cl-, S2-, Fe, Mn, Cu, Zn, Mo, B 등의 각 종 비료성분은 배액 내 매우 높은 농도로 함유되어 있어 수처리 필요성을 확인하였다. 통계분석을 통해 딸기의 배액 농도가 토마토, 파프리카, 오이보다 낮은 것으로 분석되었으며, 토마토의 경우 이러한 필수이온 농도가 가장 높으므로 비료의 재이용 측면에서는 가치 있는 자원의 대상임을 확인하였다. 시설원예단지 1m2에서 배출되는 배액의 N과 P의 부하량을 분석하였다. N은 1ha 기준 일간 토마토는 4.0kg, 파프리카 3.3kg, 오이 3.0kg, 딸기 1.5kg의 처리용량이 계 산되었다. P농도는 일간 토마토 0.5kg, 파프리카 0.6kg, 오이 0.4kg, 딸기 0.2kg을 일간 처리할 수 있는 규모와 용량 이 필요하다고 제안하였다. 본 연구를 통해 작물별 시설온실에서 배출되는 배액에 포함된 질소와 인의 양을 평가하여 배액에서의 양분적 가치산정을 통한 경제성 분석과 지속가능한 농업을 위한 시설원예단지의 수처리 시설 도입 시 반 영해야 할 처리용량 산정 시 이용할 수 있는 기초자료로 활용되길 기대하였다.

The purpose of this study was to evaluate the load of nutrients contained in the drainage discharged from the facility horticultural complex and to use them for re-use of fluids and design for introduction of water treatment plants. Representative hydroponic cultivation crops were selected as tomato, paprika, cucumber, and strawberry, and the total number of samples analyzed for water quality was 80. As a result of the analysis, since various fertilizer components such as N, P, K+, Na+, Mg2+, Ca2+, Si4 +, HCO3 -, Cl-, S2-, Fe, Mn, Cu, Zn, Mo and B are contained at very high concentrations in the drainage, the need for water treatment was confirmed. Through statistical analysis, it was analyzed that the drainage concentration of strawberries was lower than that of tomatoes, paprika, and cucumbers. In the case of tomatoes, these essential ion concentrations are the highest, so it was confirmed that they are subject to valuable resources in terms of reuse of fertilizers. The load of N and P of the drainage discharged from the facility horticultural complex 1m2 was analyzed. For N, the daily processing capacity of 4.0 kg of tomatoes, 3.3 kg of paprika, 3.0 kg of cucumbers, and 1.5 kg of strawberries was calculated based on 1 ha. It was suggested that the P concentration needs a scale and capacity that can handle 0.5 kg of tomatoes, 0.6 kg of paprika, 0.4 kg of cucumber, and 0.2 kg of strawberries per day. Through this study, the amount of nitrogen and phosphorus contained in the drainage discharged from the greenhouse of each crop was evaluated to analyze the economy. In addition, it was expected to be used as basic data that can be used to calculate the treatment capacity to be reflected when introducing water treatment facilities in facility horticultural complexes for sustainable agriculture.

The objective of this numerical study is to investigate the effect of shaft part’s diameter on the load distribution, under-fill, and metal-flow line characteristics in tubular & solid shaft yoke of Al-IMS. The outer diameter of tubular shaft yoke was changed from 30mm to 35mm, and the shaft diameter of solid shaft yoke was varied from 20mm to 25mm. In this results, the required load for production was linearly increased with increasing the tubular shaft yoke outer diameter. In the solid shaft yoke, the loads for the shaft part extending process were almost constant by 10,000kg, however, the loads for generating the yoke process, which were needed a lot of strain, were increased by 4,000kg with increasing the diameter of shaft part. The under-fill regions according to diameter of the shaft part were not observed in both products, and the metal-flow lines were also straight without folding phenomena.

In this study, we investigated the effects of EGR rate and engine load on the emission characteristics in a 4-cylinder common rail direct injection diesel engine fueled with canola oil biodiesel (BD) blended fuel. The biodiesel blend fuel, BD20 (20 vol.% biodiesel and 80 vol.% ULSD blend) was used at an engine speed of 1,500rpm. The experimental results showed that with the increasing of EGR rate, the combustion pressure and rate of heat release (ROHR) of three test fuels were decreased, and the ignition delay was extended, the carbon monoxide (CO) and particulate matter (PM) emissions increased slightly, but the nitrogen oxide (NOx) emission decreased clearly. On the other hand, with the increasing of engine load, the combustion pressure and ROHR were increased, and the CO and PM emissions decreased. However, the NOx emission was increased due to the rise of the combustion temperature.

In this study, we investigated the effects of EGR rate and engine load on the emission characteristics in a 4-cylinder common rail direct injection diesel engine fueled with canola oil biodiesel (BD) blended fuel. The biodiesel blend fuel BD20 (20 vol.% biodiesel and 80 vol.% ULSD blend) was used at an engine speed of 1,500rpm. The experimental results showed that with the increasing of EGR rate, the combustion pressure and rate of heat release (ROHR) of three test fuels decreased, and the ignition delay was extended, the carbon monoxide (CO) and particulate matter (PM) emissions increased slightly, but the nitrogen oxide (NOX) emission decreased clearly. On the other hand, with the increasing of engine load, the combustion pressure and ROHR increased, and the CO and PM emissions decreased. However, the NOX emission increased slightly due to the rise of the combustion temperature.

스펙트럼 모드해석에 기반한 풍방향 동적해석법은 1960년대에 정립된 이후, 이론적인 식에 의해서 응답을 평가할 수 있는 장점 때문에 세계 많은 나라에서 풍하중 기준으로 사용되고 있다. 이론식은 변동풍속 스펙트럼으로부터 모달풍하중 스펙트럼을 유도하고 스펙트럼해석에 의한 변동응답을 이용하여 구조물의 내풍성능을 평가할 수 있었다. 모달 풍하중 스펙트럼은 이론적 전개를 용이하게 하기 위하여 풍력계수, 난류강도, 코-코히어런스 등과 같은 바람의 성상을 단순화하여 유도된 것으로 그에 대한 타당성을 검토할 필요가 있다. 본 연구에서는 대기 경계층 풍동에서 공탄성 실험을 수행하고 하중 추정법을 이용하여 풍방향 동적하중을 구하였으며, 이를 이론적인 모달 풍하중 스펙트럼과 비교하였다. 공탄성 실험으로부터 계측된 가속도 응답에 상태공간 모드분해법을 적용하여 모달응답을 구하고 그로부터 풍방향 모달하중을 역추정하고 이론적 모달풍하중과 비교하여 그 특성을 분석하였다. 특히 풍속스펙트럼으로부터 모달 풍하중스펙트럼으로의 변환과정에서 요구되는 공력어드미턴스의 특성을 이론적 어드미턴스와 비교분석하였다. 분석결과 추정된 풍방향 동적하중 스펙트럼은 최상층 풍속에 따라 이론적 풍하중 스펙트럼의 크기가 다소 다르게 반영되어 나타났으나 진동수 특성은 매우 유사한 것을 확인할 수 있었다. 본 연구기법과 과정을 자연풍을 받는 구조물의 실계측 응답에 적용하면 자연환경상태의 풍하중을 분석하고 그에 기반하여 풍하중 모델을 정립하는데 활용 가능할 것으로 사료된다.

The dynamic along-wind response based on spectral modal analysis has been adopted as a wind load standard in many countries over the world due to the advantage of evaluating the dynamic response by the simple theoretical formula since it has been established in the 1960s. In theoretical evaluation process, the modal wind load spectrum was derived from the spectral density of longitudinal velocity fluctuation, and the spectral modal analysis is performed for the wind-resistant performance. Since the modal wind load spectrum is derived by simplifying wind characteristics such as drag coefficient, turbulence intensity, co-coherence, etc. to facilitate the theoretical development, it is necessary to examine the validity of the simplification. In this study, the aero-elastic model test was performed in the atmospheric boundary layer wind tunnel, and the modal response was separated from the acceleration responses measured from the model test by applying the state space mode decomposition technique. And then modal load was estimated in order to compare with the theoretical modal wind load. Especially, the characteristics of aerodynamic admittance used for the conversion from spectral density of wind velocity to modal wind load spectrum are mainly analyzed and compared with theoretical aerodynamic admittance. From the results, it is shown that the spectrum of estimated dynamic wind load is slightly different with the theoretical wind load spectrum according to the top wind velocity, but the overall spectral characteristics is similar in the frequency signature. Applying the process in this study to the measured response of a structure under natural wind, it can be used for estimating the wind load in the natural environment condition and establishing a wind load model based on in-situ data.

The purpose of this study was investigated to runoff characteristics and unit pollutant load of nonpoint source of first runoff from road during storm event. Road runoff generally contains significant loads of micro-particles, heavy metals and organic constituents. There were two major objectives of this study. The first objective was to characterize pattern of road runoff. The second objective was to estimate of the unit pollutants load from the road first runoff. First flush runoff for four storm events was monitored on three sites of road areas in Daejeon along with traffic volume. The quantity of road runoff and quality constituents, including chemical oxygen demand(CODcr), sus-pended solids(SS), biological oxygen demand(BOD5), total nitrogen(T-N), total phosphorus (T-P), heavy metals were analyzed. The results showed that the event mean concentration(EMC) of BOD5, CODcr, SS, T-N, T-P, Fe, Cu, Cr, Zn, Pb average rages were 66 mg/L, 272 mg/L, 263 mg/L, 13.77 mg/L, 0.52 mg/L, 8.937 mg/L, 0.130 mg/L, 0.113 mg/L, 0.616 mg/L, 0.171 mg/L, respectively. The average unit pollutants load for first runoff from road BOD5, CODcr, SS, T-N, T-P, Fe, Cu, Cr, Zn, Pb were 102, 298, 552, 23.4, 0.77, 17.24, 0.47, 0.09, 1.18, 0.58 g/a/day, and 1.243, 3.685, 3.282, 0.180, 0.009, 0.115, 0.002, 0.002, 0.010, 0.0035 g/a/mm, respectively.

Composites have wide applications in aerospace vehicles and automobiles because of the inherent flexibility in their design lot improved material properties. Composite tubes in particular, are potential candidates for their use as energy absorbing elements in crashworthiness applications due to their high specific energy absorbing capacity and the stroke efficiency. Their failure mechanism however is highly complicated and rather difficult to analyze. This includes fracture in fibers, in the matrix and in the fiber-matrix interface in tension, compression and shear. The purpose of this study is to investigate the energy absorption characteristics of Gr/E(Graphite/Epoxy) tubes on static and impact tests. The collapse characteristics and energy absorption of a variety of tubes have been examined. Changes in the lay-up which increased the modulus increased the energy absorption of the tubes. Based on the test results, the following remarks can be made: Among CA15, CA00 and CA90 curves the CA90 tube exhibits the highest crush load throughout the whole crush process, and max load increases as interlaminar number increase. Among all the tubes type CC90 has the largest specific crushing stress of 52.60 kJ/kg which is much larger than other tubes.

연구목적: 건축물의 성능위주설계의 평가결과는 가연물의 연소실험으로 측정된 열방출률에 의해 크게 좌우된다. 본 연구는 주거공간의 성능위주설계의 신뢰성을 높이기 위해 주거공간의 가연물을 대상으 로 화재실험을 실행하여 주거공간의 열방출률을 측정하였다. 연구방법: 화재실험은 대형콘칼로리미터 시험기의 집연 후드의 아래에 주거공간의 가연물을 배치한 후에 소형화원으로 점화하여 산소소모법에 의해 열방출률을 측정하였다. 또한 화재실험은 주거공간 중에 방 공간과 부엌 공간으로 구분하여 가연 물을 배치하고, 가연물을 점화원으로 점화하여 가연물의 화염형상 및 시간별 가연물 간의 화염전파를 관찰하였다. 연구결과: 부엌 공간과 김치 냉장고의 최대열방출률은 각각 2MW, 1.2MW이었다. 방 공간 은 최대열방출률이 2.8MW로 크고 연소확대가 매우 빠른 것을 알 수 있었다. 결론: 주거공간 가연물의 연소실험을 통해 측정한 열방출률을 모델화하여 주거공간의 디자인 화재곡선을 제안하였으며 이는 주 거공간의 성능위주설계의 신뢰성을 향상하는데 기여할 것으로 판단된다.

Purpose: The design fire sources based on the heat release rate of combustibles heavily influences the evaluation result of a performance-based design. The objective of the present study is to provide the information on the heat release rate for various combustibles in residential spaces. Method: Large scale calorimeter were used according to th amount of the combustibles. The combustibles were ignited using a small amount of fire source. The combustion gas generated in the experiment was collected inside the duct to measure the gas concentration(oxygen, carbon dioxide, carbon monoxide) and the heat release rate were calculated by the oxygen consumption method. The fire experiments were carried out with single combustible, simulated room and kitchen. Result: The results of these tests showed that the peak heat release rate were 1.2 MW for Kimchi refrigerator and 2 MW for Kitchen. In particular, a room had the highest fire risk in terms of the peak heat release rate, 2.8 MW. Conclusion: The design fire curve was proposed based on the heat release rate of the combustibles, which is expected to increase the reliability of the performance-based design in residential spaces.

플로팅 건물의 시간이력 해석을 위하여 필요한 최소한의 입력하중의 개수를 확인하기 위하여, 100개의 불규칙 풍파랑 하중에 대한 동수역학 해석을 수행하여 좌우동요와 횡동요를 고찰하고, 이 100개의 결과 중에서 30개를 건물의 밑면에 작용하는 입력하중으로 사용하여 부분골조 해석을 수행하였다. 30개의 해석결과 중 7와 15개의 샘플을 추출하여 평균과 표준편차를 비교하였다. 7개의 샘플링에 의한 지붕층의 변위값이나 가속도 및 모멘트의 값은 30개의 샘플의 평균값의 5% 이내의 오차가 발생하였으므로, 불규칙하중에 대한 해석 및 설계시 7개의 풍파랑 불규칙 하중에 대한 상부구조물의 평균값을 사용할 수 있음을 시사하였다. 그러나 표준편차의 경우는 샘플링의 개수에 따라 편차가 크게 발생하였으므로 확률적인 분포를 고려한 평가에서는 7개 하중의 평균값은 신뢰성이 떨어질 것으로 판단된다. 라틴하이퍼큐브에 의한 7개의 샘플링의 평균치와 표준편차는 30개 샘플링의 값과 근사하여, 상부구조물의 설계 및 확률분포의 추정시 안정적인 방법으로 사용될 수 있을 것임을 시사하였다.

To study the effective sampling number of wind and wave loading on a floating building, 30 rolling and sway accelerations are selected from 100 hydrodynamic analysis samples, to find the historical response of the acceleration and displacement and the moment of beam and column of the building frame using substructure analysis. From 30 results, 7 and 15 are randomly sampled and the response of them are compared with that of 30 sampling. The average value of 7 random sampling shows good correspondence with the 30 sampling value but the standard deviation of 7 sampling is different from that of 30 sampling. But in case of 7 Latin Hypercube sampling, it shows good correspondence with 30 sampling result.

The column-supported wall system structures are being built according to increase of population and accelerated urbanization. In this study, characteristics of shear wall system subjected to lateral load is analyzed and the stress distribution and deformation characteristics of the column-supoorted wall system structures were compared. The results obtained from the model using the plane stress elements were compared with the results of the model with a beam-column elements for column - supported wall type structures. The bending moment of the model with beam-column elements was 0.53 times of that of model with plane stress elements at the end of transfer girder. And the bending momomet at the center of transfer girder consist of beam-column elements was 1.59 times of that of model with plane stress elements.

Micro structure observation for low carbon steel base material and heat treatment(annealing),performing a tensile test and impact test, the specimen after the impact test is intended to evaluate thecrack propagation characteristics by performing a fractal dimension analysis. The tensile strength of thebase materials were observed higher compared to the heat treated materials, impact absorbed energy ofheat treated materials was a higher than base materials. Impact Test and fractal dimension of the sideof the test specimen was shown significantly more test temperature increases, heat treated material washigher than the base material.