• Steel and Composite Structures
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• 제16권5호
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• pp.491-506
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• 2014

Buckling-restrained braces (BRBs) have excellent hysteretic behavior while buckling-restrained braced frames (BRBFs) are susceptible to residual lateral deformations. To address this drawback, a novel self-centering (SC) BRB with Basalt fiber reinforced polymer (BFRP) composite tendons is presented in this work. The configuration and mechanics of proposed BFRP-SC-BRBs are first discussed. Then an 1840-mm-long BFRP-SC-BRB specimen is fabricated and tested to verify its hysteric and self-centering performance. The tested specimen has an expected flag-shaped hysteresis character, showing a distinct self-centering tendency. During the test, the residual deformation of the specimen is only about 0.6 mm. The gap between anchorage plates and welding ends of bracing tubes performs as expected with the maximum opening value 6 mm when brace is in compression. The OpenSEES software is employed to conduct numerical analysis. Experiment results are used to validate the modeling methodology. Then the proposed numerical model is used to evaluate the influence of initial prestress, tendon diameter and core plate thickness on the performance of BFRP-SC-BRBs. Results show that both the increase of initial prestress and tendon diameters can obviously improve the self-centering effect of BFRP-SC-BRBs. With the increase of core plate thickness, the energy dissipation is improved while the residual deformation is generated when the core plate strength exceeds initial prestress force.

• Journal of Ecology and Environment
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• 제34권4호
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• pp.411-423
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• 2011

This study was conducted to quantify soil $CO_2$ efflux using the continuous measurement method and to examine the applicability of an automatic continuous measurement system in a Korean deciduous broad-leaved forest. Soil respiration rate (Rs) was assessed through continuous measurements during the 2004-2005 full growing seasons using an automatic opening/closing chamber system in sections of a Gwangneung temperate deciduous forest, Korea. The study site was an old-growth natural mixed deciduous forest approximately 80 years old. For each full growth season, the annual Rs, which had a gap that was filled with data using an exponential function derived from soil temperature (Ts) at 5-cm depth, and Rs values collected in each season were 2,738.1 g $CO_2$ $m^{-2}y^{-1}$ in 2004 and 3,355.1 g $CO_2$ $m^{-2}y^{-1}$ in 2005. However, the diurnal variation in Rs showed stronger correlations with Ts (r = 0.91, P < 0.001 in 2004, r = 0.87, P < 0.001 in 2005) and air temperature (Ta) (r = 0.84, P < 0.001 in 2004, r = 0.79, P < 0.001 in 2005) than with deep Ts during the spring season. However, the temperature functions derived from the Ts at various depths of 0, -2, -5, -10, and -20 cm revealed that the correlation coefficient decreased with increasing soil depth in the spring season, whereas it increased in the summer. Rs showed a weak correlation with precipitation (r = 0.25, P < 0.01) and soil water content (r = 0.28, P < 0.05). Additionally, the diurnal change in Rs revealed a higher correlation with Ta than that of Ts. The $Q_{10}$ values from spring to winter were calculated from each season's dataset and were 3.2, 1.5, 7.4, and 2.7 in 2004 and 6.0, 3.1, 3.0, and 2.6 in 2005; thus, showing high fluctuation within each season. The applicability of an automatic continuous system was demonstrated for collecting a high resolution soil $CO_2$ efflux dataset under various environmental conditions.

• 한국의류학회지
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• 제34권2호
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• pp.189-199
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• 2010

This study develops a coverall design for the body shape and movement of infants. This research analyzed these processes: 1. The current coverall styles preferred for infants. 2. The appropriate products for the real size, body shape, movement, and fit of infants. 3. The observations of the 6 months to 9 months movement and development of infants. 4. The design and creation of a new coverall base in this study, and to check the suitable test the developed coverall design for the infant. The result of this study are: A coverall for infants that lie or crawl on the floor must avoid opening in the center front and a gore has to be added at the crotch of the pants for the better movement of infants. These ways provide infants a neat appearance and easy movement. The test of developed designs shows that the developed coverall design covers the size gap of the trunk loop according to the growth of the infant and the movement of the legs; in addition it provides a positive aesthetic effect. The waistline in the developed coverall (a waistline that should exist lower than the body waistline of the infant) can reduce seam stress because the pressure of the seam line can be absorbed in a dipper. It is one of the suitable design points for infants lying prone all day long in this study.

• 한국경제지리학회지
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• 제18권4호
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• pp.522-538
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• 2015

본 연구는 대규모 유가공업체 매일유업과 전라북도 고창군 낙농가 간 유기농 원유 계약생산을 대상으로, 계약생산이 고창군에서 시작된 배경을 고찰하고, 계약생산의 실제와 계약주체 간 관계를 중심으로 계약생산의 특징을 규명하고, 이로 인해 나타나는 지역 낙농업의 변화를 설명하였다. 사례지역의 유기농 원유 계약생산은 시장개방으로 위기에 처한 기업의 제품 다각화 전략과 고창군의 청정 환경, 그리고 지방정부와 낙농가의 긍정적 태도가 맞물리면서 성립되었다. 고창군의 유기농 원유 계약생산은, 한편으로는 참여 농가의 생산규모를 선택적으로 증가시킴에 따라 역내 낙농가 간 생산규모의 격차를 유발하고 있으나, 다른 한편으로는 계약농가의 유기농가로의 전환을 통해 역내 유기농업의 확산을 가져옴에 따라 관행농업 중심의 계약생산에 대한 일반의 우려를 불식시키고 있다.

• 대한조선학회 특별논문집
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• 대한조선학회 2007년도 특별논문집
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• pp.118-127
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• 2007

SAW(Submerged Arc Welding) process is generally applied to a wide range of welding area in the fabrication of steel structure. This process has a good characteristic properties such as the high quality of welds and the high deposition rates, but in case of welding on a thick steel plate, it also has higher cold crack susceptibility than that of a thin steel plate. The purpose of this research is to find the main factor of crack generation and clarify the countermeasure for crack prevention, and then establish the optimum welding condition in a heavy thick steel plate. The results of this study are as follows, 1. The cause of crack generation is found the diffusible hydrogen penetrated into weld metal by decomposition of the remained moisture in SAW flux during welding. 2. For the removal of diffusible hydrogen, the raw materials of SAW flux are to be dehydrated at the high temperature in the initial manufacturing stage. 3. Mechanical properties of weld metal welded with the dehydrated SAW flux were evaluated very excellent, furthermore the weld metal has been proved to have low diffusible hydrogen content with 3.1ml /100g. 4. The weldability and quality welded with thick steel plates were improved by establishing the new optimum welding condition.

• 한국광학회지
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• 제17권3호
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• pp.290-295
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• 2006

전기전도도가 높은 구리선 도파로에 THz 전자기파의 결합은 THz 유선방식의 전파에 있어 테라파의 크기 및 주파수 특성을 결정짓는 중요한 요인 중의 하나이다. 본 연구에서는 직경 $480{\mu}m$, 길이 23 cm의 구리선 도파로에 테라파를 전파시켜 1 THz 주파수 범위를 가진 THz 펄스를 측정하였다. 도파로와 transmitter chip 또는 receiver chip 사이의 공극 간격을 최대 $275{\mu}m$까지 확대하여 송신부와 수신부의 결합 특성을 접촉상태와 비교 분석하였다. 실험결과 송신부의 결합민감도가 수신부보다 약 3배 이상 높게 나타났으며 수신부에서 도파로와 receiver사이의 공극을 통하여 테라파가 공기 중으로 전파됨을 알 수 있었다. 또한 구리선 도파로에 pin hole를 위치시켜 pin hole의 직경에 따른 테라파의 변화를 연구하였으며 대부분의 THz field는 구리선 표면에 분포됨을 확인할 수 있었다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.897-900
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• 2008

경제의 세계화와 지속적인 국제건설시장 개방으로 인해 많은 국가들이 더욱더 치열해지는 국내외 건설 시장의 경쟁에 직면하고 있다. 이러한 배경으로 각 나라들도 해외시장에서 여러 가지 기술과 도구를 통해 최대한 수익을 창출할 수 있도록 노력하고 있다. 그러나 국가 간의 계약에서 클레임의 발생은 계약자들한테 발전의 걸림돌이 되었고 많은 손실과 피해를 초래해 왔다. 이에 따라서 건설 클레임의 관리는 복잡한 경제 활동 중 제일 중요한 도전이라고도 과언이 아니다. 현재 미국과 프랑스 같은 선진국들이 계약관리와 클레임에 대한 방법론들을 통해서 많은 발전을 취득해 온 반면에 한국과 중국 같은 아시아 국가들은 선진국에 비해 아직 큰 격차가 존재하고 있다. 본 연구는 한국과 중국의 건설 클레임을 비교 분석하여 공통점과 차이점을 제시하는 것을 목적으로 한다.

• Steel and Composite Structures
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• 제27권6호
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• pp.727-745
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• 2018

The design criteria and the corresponding performance levels characterize the response of extended stiffened end-plate beam-to-column joints. In order to guarantee a ductile behavior, hierarchy criteria should be adopted to enforce the plastic deformations in the ductile components of the joint. However, the effectiveness of thesecriteria can be impaired if the actual resistance of the end-plate material largely differs from the design value due to the potential activation of brittle failure modes of the bolt rows (e.g., occurrence of failure mode 3 in the place of mode 1 per bolt row). Also the number and the position of bolt rows directly affect the joint response. The presence of a bolt row in the center of the connection does not improve the strength of the joint under both gravity, wind and seismic loading, but it can modify the damage pattern of ductile connections, reducing the gap opening between the end-plate and the column face. On the other hand, the presence of a central bolt row can influence the capacity of the joint to resist the catenary actions developing under a column loss scenario, thus improving the joint robustness. Aiming at investigating the influence of these features on both the cyclic behavior and the response under column loss, a wide range of finite element analyses (FEAs) were performed and the main results are described and discussed in this paper.

• 설비공학논문집
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• 제29권8호
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• pp.419-428
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• 2017

In this study, energy loss due to ventilation load in the dock system was analyzed through simulation. Also, flow generated in the dock system of the warehouse was measured using manufactured measuring devices. Numerical simulation was conducted by simulating the most common picking tasks by examining the actual working environment. Incompressible and unsteady turbulent flows were assumed, and the turbulence model was the k-e standard model. Proper grid was selected through grid dependency test. Measurement was conducted using Honeywell and Vaisala sensors, and flow and temperature inside the warehouse were measured and compared with simulation results to validate simulation. When comparing amount of loss occurring in two hours and amount of loss occurring in 15 minutes, docking time of the former was eight times longer but energy loss was 3.8 times lower. Ventilation load occurring during the initial period after opening docking system accounted for a large proportion of total ventilation load. Also, comparing the load when the dock was closed and the load when the truck was parked, ventilation load was significantly higher than load due to heat conduction from the wall. Therefore, in improving the docking system, it is effective to reduce the gap by improving compatibility of the docking system and truck, rather than wall material.

• 경영과정보연구
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• 제4권
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• pp.29-66
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• 2000

The current economic environmental changes such as globalization, information and opening of the market is calling for or needing the more rapid change of management and/or marketing strategies of the company than they did before to survive in tile borderless international competition. Under this situation, this study focuses on the correspondence strategies of Electronic Commerce which is one of the key elements to overcome or lead the above demands through seeking the problems of the current EC acception and application specially in Chollabuk Do province. For the above purpose, this study surveys the questionary with business firms of above area and figures out what is the correlation between business form and size and EC acception and application and what is the problems on it. And than provides several counter strategies which are following based on the survey to keep this area companies from out of business and lead the above economic environmental changes. To expand the adoption and application of EC to this area, firstly, top managers of the company must recognize the necessity and importance of EC compared with traditional commerce and change their perception and attitude concerning EC positively, and than try to accept it as soon as possible. Secondly, the company need the retained earning to invest to EC and educate their managers and employees with total participation. Thirdly, local government has to improve its attention to EC as a best way or opportunity to reduce and overcome the economical gap and development its economy because EC can remove the physical time or distance and space, scale and capital limitations. Finally, government has to expand and establish information infrastructure such as technical infrastructure(communication and security technology), Functional infrastructure like standard protocol, Organizational infrastructure(interchange agreement, relative law) and social infrastructure to improve efficient electronic transaction which can Increase the company' international compatitiveness under the current economy trend.