• Earthquakes and Structures
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• 제19권4호
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• pp.273-286
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• 2020

The pile group foundation is widely used for gravity pier of high-speed railway bridges in China. If a moderate or strong earthquake occurs, the pile-surrounding soil will exhibit obvious nonlinearity and significant pile group effect. In this study, an improved pushover analysis model for the pile group foundation with consideration of pile group effect is presented and validated by the quasi-static test. The improved model uses simplified springs to simulate the soil lateral resistance, side friction and tip resistance. PM (axial load-bending moment) plastic hinge model is introduced to simulate the impact of the axial force changing of pile group on their elastic-plastic characteristics. The pile group effect is considered in stress-stain relations of the lateral soil resistance with a reduction factor. The influence factors on nonlinear characteristics and plastic hinge distribution of the pile group foundation are discussed, including the pier height, longitudinal reinforcement ratio and stirrup ratio of the pile, and soil mechanical parameters. Furthermore, the displacement ductility factor, resistance increase factor and yielding stiffness ratio are provided to evaluate the seismic performance of soil-pile system. A case study for the pile group foundation of a railway simply supported beam bridge with a 32 m-span is conducted by numerical analysis. It is shown that the ultimate lateral force of pile group is not determined by the yielding force of the single one in these piles. Therefore, the pile group effect is essential for the seismic performance evaluation of the railway bridge with pile group foundation.

• 한국환경교육학회지:환경교육
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• 제18권1호
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• pp.55-69
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• 2005

This study aims to investigate and practically examine the effect of environmental qualifications based on the theoretical background on the area. First, the economic effect of the acquisition of the qualifications was to be studied from the viewpoints of individuals and from an actual analysis on it, its effect was to be proved. Second, its non-economic effect was to be proved from the same way as the first analysis. On the basis of theoretical background, a study model was formulated in a way that the effect of qualifications in individuals side was divided into an economic effect (wage, employment, promotion, job-switching) and non-economic effect (self-development, self-efficiency, satisfaction on the job, ability to cope with the advancement of technology, job performance, signal effect, the settlement of uneasiness at unemployment). Then, survey was carried out with questions designed in accordance with this model. The hypotheses were proved as the following. First, for hypothesis 1(Environmental qualifications will bring up positive impacts on an individuals economic effect), environmental qualifications was shown to have positive impacts on wage, job-switching in personal economic effect. But, no personal economic effect appeared for employment and promotion. Second, for hypothesis 2(Environmental qualifications will bring up positive impacts on an individuals non-economic effect), environmental qualifications appeared to have positive impacts on self-efficiency, ability to cope with the advancement of technology, job performance and signal effect. Besides, no impact was shown in satisfaction on the job and the settlement of uneasiness at unemployment and self-development.

• 한국수자원학회논문집
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• 제33권5호
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• pp.647-658
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• 2000

본 연구에서는 공급측면 산업연관분석모형을 사용하여 물공급지장이 끼치는 산업의 전방효과를 분석하고자 하였다. 여기서 분석된 공급지장비용은 수도사업의 신뢰도 결정에 사용될수 있으며 물의 공급부족이 발생할 경우 물의 효율적 배분을 위한 정책적 기초를 제공할 수 있다. 따라서 산업연관분석을 이용하여 수도부문이 차지하는 국민경제적 위치를 확인하고 공급지장으로 인한 산업간 직·간접 피해를 분석하였다. 또한 가뭄시 중요한 공급우선 순위 결정을 위한 공급지장지수를 제안하였다. 한편 가뭄의 발생은 지역적인 특성을 가지고 있어서 전국산업연관표를 이용한 지역수준의 공급지장비용이 과대 도는 과소평가될 여지가 있다. 따라서 경남지역산업연관표를 통해 산정한 공급지장비용을 전국산업관표와 비교·분석하였다.

• 한국유기농업학회지
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• 제30권3호
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• pp.351-374
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• 2022

In recent years, the development of rice industry has been highly valued by the state. In hubei area, due to the development of the modernization and the shortage of labor, traditional way of rice cultivation methods is facing serious challenges, and economic benefits have become the decisive factor for the effective promotion and application of rice cultivation methods. According to the research results, first, in the input-side analysis, in the CCR model, D5, D12, D26, D28, D32, D36 farmers with high efficiency appear. The analysis result shows that among the 60 farmers, the average efficiency is 89%, and there is an inefficiency of 11%. In the BCC model, 14 farmers were identified as high-efficiency farmers, with an average efficiency of 0.9453. Second, in direct seeding cultivation of rice, the average scale efficiency is 0.9227, while the average pure technical efficiency is 0.9644. This shows that the effect of scale efficiency is greater than that of purely technical factors, ignoring the reasons for the low operational efficiency of direct seeding cultivation farmers. It can be predicted that with the further deepening of farmers' understanding of this planting mode, the proportion of rice direct seeding may be further expanded in the future. Relevant agricultural departments should further promote this technology to farmers, study the direct seeding technology using scientific methods, and evaluate the changes of this cultivation mode. The agricultural departments of government should concern about the climate risk assessment of direct seeding rice, the environmental impact assessment caused by the extensive use of herbicides, the application of mechanical technology in the process of direct seeding, the lodging of direct seeding rice, and other related issues.

• 한국지반공학회논문집
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• 제39권10호
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• pp.27-39
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• 2023

극한홍수에 대응하기 위한 홍수 위험도 관리의 필수 요소인 홍수 위험도 평가를 위해서는 댐 및 하천제방과 같은 홍수방어시설에 대하여 여러 파괴 메커니즘을 고려한 신뢰도 해석을 수행해야 한다. 본 연구에서는 수위급강하에 의한 제체 사면의 시간에 따른 확률론적 안정성 평가에 대하여 연구하였다. 유한요소 해석에 의한 침투해석 결과를 사면안정 해석에 연동하여 Monte Carlo Simulation을 수행함으로써 수위급강하에 따른 제체의 시간의존적 거동을 연구하고 파괴확률을 계산하여 제방의 취약도 곡선을 작성하였다. 수위급강하에 의한 사면의 파괴확률은 특정 수위까지는 매우 작은 값을 유지하지만, 그 이상에서는 수위가 증가함에 따라 급격하게 증가하는 현상을 보였다. 또한 취약도 곡선은 수위 하강 속도에 크게 영향을 받았다. 수위 저하 속도는 수문 시나리오에 의한 수위의 변동해석을 통하여 결정되므로 수위급강하에 따른 제방 제외지 사면의 안정성은 기후변화에 따라 크게 영향을 받을 것으로 판단된다.

• 한국운동역학회지
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• 제17권2호
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• pp.177-185
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• 2007

Even though there were no clear definitions of the short game and short game distance, short game capability is crucial for a good golf score. Generally, chip shot and pitch shot are regarded as two principal components of the short game. Chip shot is a short, low trajectory shot played to the green or from trouble back into play. Pitch shot is a high trajectory shot of short length. Biomechanical studies were conducted usually to analyze full swing and putting motions. The purpose of the study was to reveal the kinematical differences between professional golfers' 30 yard $53^{\circ}wedge$ chip shot and $56^{\circ}wedge$ pitch shot motions. Fifteen male professional golfers were recruited for the study. Kinematical data were collected by the 60 Hz three-dimensional motion analysis system. Statistical comparisons were made by paired t-test, ANOVA, and Duncan of the SPSS 12.0K with the $\alpha$ value of .05. Results show that both the left hand and the ball were placed left of the center of the left and right foot at address. The left hand position of the chip shot was significantly left side of that of the pitch shot. But the ball position of the pitch shot was significantly right side of that of the chip shot. All body segments aligned to the left of the target line, open, at address. Except shoulder, there were no significant pelvis, knee, and feet alignment differences between chip shot and pitch shot. These differences at address seem for the ball height control. Pitch shot swing motions(the shoulder and pelvis rotation and the club head travel distance) were significantly bigger than those of the chip shot. Club head velocity of the pitch shot was significantly faster than that of the chip shot at the moment of impact. This was for the same shot length control with different lofted clubs. Swing motion differences seem mainly caused by the same shot length control with different ball height control.

• 대한교통학회지
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• 제28권6호
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• pp.85-97
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• 2010

본 연구는 정류소에서 여러노선의 버스가 동시에 몰려들어오는 버스몰림운행의 실태를 파악하고 이로 인해서 야기되는 문제점을 개선하기 위하여 버스몰림 운행지속시간 모형을 추정하고 버스몰림운행에 영향을 미치는 요인을 분석하였다. 버스몰림지속시간의 관측치를 대상으로 8개의 지속시간에 대한 분포를 검토하여 가장 적합도가 높게 나타난 weibull 분포를 가정한 모형을 개발하였다. 18개 영향변수를 검토하였으며 정차면수, 정차면수당 노선수, 노선당 최대 승하차인원을 설명변수로 하는 버스몰림운행 지속시간 모형을 개발하였다. 중앙버스전용차로(도봉미아로)와 가로변 전용 및 일반차로(통일의주로)에 대한 모형을 각각 도출하여 비교하였다. 그 결과, 도봉미아로의 몰림지속시간은 통일의주로에 비해 교통량에 대한 영향을 많이 받으며, 통일의주로는 도봉미아로에 비해 정차면수와 정차면수당 노선수, 노선당 최대 승하차인원에 많은 영향을 받는 것으로 나타났다. 개발된 모형을 토대로 버스몰림운행 현상의 완화방안을 제시하였다.

• Nuclear Engineering and Technology
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• 제40권4호
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• pp.255-268
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• 2008

The greater demand for electricity and the available capacity within safety margins in some operating NPPs are prompting nuclear utilities to request license modification to enable operation at a higher power level, beyond their original license provisions. Such plant modifications require an in-depth safety analysis to evaluate the possible safety impact. The analysis must consider the thermo hydraulic, radiological and structural aspects, and the plant behavior, while taking into account the capability of the structures, systems and components, and the reactor protection and safeguard systems set points. The purpose of this paper is to introduce international experiences and approaches for implementation of power uprates related to the reactor thermal power of nuclear power plants. The paper is intended to give the reader a general overview of the major processes, work products, issues, challenges, events, and experiences in the power uprates program. The process of increasing the licensed power level of a nuclear power plants is called a power uprate. One way of increasing the thermal output from a reactor is to increase the amount of fissile material in use. It is also possible to increase the core power by increasing the performance of the high power bundles. Safety margins can be maintained by either using fuels with a higher performance, or through the use of improved methods of analysis to demonstrate that the required margins are retained even at the higher power levels. The paper will review all types of power uprates, from small to large, and across various reactor types, including light and heavy water, pressurized, and boiling water reactors. Generally, however, the content of the report focuses on power uprates of the stretch and extended type. The International Atomic Energy Agency (IAEA) is developing a technical guideline on power uprates and side effects of power uprates in nuclear power plants.

• 산업융합연구
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• 제17권1호
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• pp.33-39
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• 2019

본 연구에서는 기후변화에 대응하는 도시개발의 실천적 실행을 위해서 기후위험요인 측면과 환경적인 측면으로 대별하여 도시개발 방향과 시사점을 제시하는데 목적을 두었다. 연구방법으로는 정성적인 자료조사와 분석을 통해 이루어졌다. 연구결과, 기후위험요인에 따른 도시개발방향은 도시계획수립시 기후변화 영향을 통합적으로 고려할 수 있는 지역별 부문별 영향 및 취약성 분석을 실시함으로써 자연재난에 대한 피해예방 시스템 구축과 자연재해 위험도 분석을 실시해 도시개발을 할 수 있는 여건 마련의 중요성을 강조하였다. 환경적측면의 도시개발방향은 친환경적인 도시개발을 위해서는 도시계획수립시 대중교통지향적인 도시개발(TOD, Transit­oriented Development)의 추진이 지속가능하고 실행적인 도시개발을 실현하는데 그 필요성을 제시하였다. 향후 연구방향은 보다 더 정량적이고 실증적인 규명을 위한 연구가 보완되어야 할 것이다.

• Journal of Welding and Joining
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• 제30권1호
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• pp.64-71
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• 2012

The characteristics of high heat input (342kJ/cm) EG (Electro Gas Arc) welded joint of EH36-TM steel has been investigated. The weld metal microstructure consisted of fine acicular ferrite (AF), a little volume of polygonal ferrite (PF) and grain boundary ferrite (GBF). Charpy impact test results of the weld metal and heat affected zone (HAZ) met the requirement of classification rule (Min. 34J at $-20^{\circ}C$). In order to evaluate the relationship between the impact toughness property and the grain size of HAZ, the austenite grain size of HAZ was measured. The prior austenite grain size in Fusion line (F.L+0.1 mm) was about $350{\mu}m$. The grain size in F.L+1.5 mm was measured to be less than $30{\mu}m$ and this region was identified as being included in FGHAZ(Fine Grain HAZ). It is seen that as the austenite grain size decreases, the size of GBF, FSP (Ferrite Side Plate) become smaller and the impact toughness of HAZ increases. Therefore, the CGHAZ was considered to be area up to 1.3mm away from the fusion line. Results of TEM replica analysis for a welded joint implied that very small size ($0.8\sim1.2{\mu}m$) oxygen inclusions played a role of forming fine acicular ferrite in the weld metal. A large amount of (Ti, Mn, Al)xOy oxygen inclusions dispersed, and oxides density was measured to be 4,600-5,300 (ea/mm2). During the welding thermal cycle, the area near a fusion line was reheated to temperature exceeding $1400^{\circ}C$. However, the nitrides and carbides were not completely dissolved near the fusion line because of rapid heating and cooling rate. Instead, they might grow during the cooling process. TiC precipitates of about 50 ~ 100nm size dispersed near the fusion line.