• 한국지반환경공학회 논문집
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• 제7권3호
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• pp.69-76
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• 2006

본 연구는 모래지반에서 공동위에 위치한 연속기초의 지지력거동을 연구하기 위하여 강사법으로 조성된 모래지반에서 모형실험을 수행하였다. 모형실험결과와 이론식을 비교하여 지하공동이 연속기초의 지지력에 영향을 미치는 한계범위를 도출하였다. 한계범위의 크기는 기초의 형상, 지반특성, 공동크기, 공동형상 등 여러 가지 인자에 의존한다. 지하공동의 깊이가 편심거리보다 극한지지력에 더 큰 영향을 주는 것으로 나타났다. 또한 연속기초에 미치는 지하공동의 영향은 편심거리에 따른 지지력 감소현상 뿐만 아니라 연속기초의 부등침하 현상에도 큰 영향을 줄 것으로 판단되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.527-529
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• 2004

This paper researched leakage current characteristics of EHW insulators(36,000lbs) to artificially contaminated clay and kaolin through construction of long-periods testing facility. Insulators were contaminated and classified into the ESDD level(B, C and D) under IEC Pub. 60507 standards method. As a result of tests, leakage current of the heavily contaminated D level to clay was approximately 2,260 $[\muA]$, which is contaminated to kaolin was approximately 3,200 $[\muA]$, during initial rainfall. However after raining, leakage current of naturally washed contamination insulators was lower at approximately 300 $[\muA]$. As regular temperature $20^{\circ}C$, leakage current increased greatly in case humidity density was over $72\%$. But, leakage current was not influenced by temperature variation in case of regular $\%$ humidity.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.872-898
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• 2007

전동차 자동검사 장치의 하나인 판타그라프 습판마모 자동측정 시스템은 첨단 기술인 머신비젼 기법을 이용하여 습판체의 마모상태를 검수자의 육안검사 없이 마모량과 교체시점 등을 판단하는 시스템이다. 본 논문에서는 우천시 빗물로 인한 노이즈(Noise)가 영상에 입력되어 판타그라프 습판의 에지(Edge)를 검출하는데 영향을 미쳐 신뢰성을 저하시키는 요인이 된다. 이러한 노이즈 제거를 위해 평활화(Smoothing) 처리로서 필터링 기법을 적용한 평균 마스크(Averaging mask), 중간값 필터(Median filter) 기법을 사용하여 문제점 등을 확인하고, 머신비젼 기술에서 사용되는 영상측정에 있어 에지 추출(Edge Detection)이 노이즈의 영향을 받지 않고 안정된 결과를 획득할 수 있도록 유도하고자 한다.

• 산업기술연구
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• 제18권
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• pp.7-16
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• 1998

This paper is an experimental study of investigating the reinforcing effect and the behavior of cohesionless slope installed with reticulated root pils. Reduced scale model tests with plane strain conditions were performed to study the behavior of the strip footing located on the surface of cohesionless slopes reinforced with root piles. Model tests were carried out with Jumunjin Standard Sand of 45% relative density prepared by raining method to have an uniform slope foundation during tests. Slope of model foundation was 1 : 1.5 and a rigid model slop. Parametric model tests were performed with changing location of model footing, arrangements of root piles and angles of pile installation. On the other hands, the technique with camera shooting was used to monitor sliding surface formed with discontinuty of dyed sand prepared during formation o foudation. From test results, parameters affecting the behavior of model footing were analyzed qualitatively to evaluate their effects on the characteristic of load - settlement, ultimate bearing capacity of model footing and failure mechanism based on the formation of failure surface.

• Geomechanics and Engineering
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• 제15권1호
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• pp.695-710
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• 2018

Formation of a soil plug in an open-ended pile is a very important factor in determining the pile behavior both during driving and during static loading. The degree of soil plugging can be represented by the incremental filling ratio (IFR) which is defined as the change in the plug length to the change of the pile embedment length. The experimental tests carried out in this research contain 138 tests that are divided as follows: 36 tests for single pile, 36 tests for pile group ($2{\times}1$), 36 tests for pile group ($2{\times}2$) and 30 pile group ($2{\times}3$). All tubular piles were tested using the poorly graded sand from the city of Karbala in Iraq. The sand was prepared at three different densities using a raining technique. Different parameters are considered such as method of installation, relative density, removal of soil plug with respect to length of plug and pile length to diameter ratio. The soil plug is removed using a new device which is manufactured to remove the soil column inside open pipe piles group installed using driving and pressing device. The principle of soil plug removal depends on suction of sand inside the pile. It was concluded that the incremental filling ratio (IFR) is changed with the changing of soil state and method of installation. For driven pipe pile group, the average IFR for piles in loose is 18% and 19.5% for L/D=12 and 15, respectively, while the average of IFR for driven piles in dense sand is 30% and 20% for L/D=12 and L/D=15 respectively. For pressed method of pile installation, the average IFR for group is zero for loose and medium sand and about 5% for dense sand. The group capacity increases with the increase of IFR. For driven pile with length of 450 mm, the average IFR % is about 30.3% in dense sand, 14% in medium and 18.3% for loose sand while when the length of pile is 300 mm, the percentage equals to 20%, 17% and 19.5%, respectively.

• 현장농수산연구지
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• 제12권1호
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• pp.29-38
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• 2010

본 연구는 기존의 무논점파기의 문제점(새 피해, 파종한 종자의 건조현상, 강우 또는 관개 시 가벼운 볍씨 또는 어린 유묘의 뜨는 문제 등)으로 초기 입묘가 불량한 요인을 개선하기 위하여 시험을 추진하였으며 얻어진 결과는 다음과 같다. 1. 롤러 간의 피복재 사상(모래형) 규산질비료의 피복량이 일정치 않았다. 2. 기존의 무논점파 파종장치의 정확한 점파작업이 요구되었으며 파종작업 시 볍씨가 롤러 홈 회전과정에서 발생되는 파손이 인정되었으며 이에 대한 개선이 요구되었다. 3. 사상 규산질비료의 정밀한 피복작업이 미진하였으며 이를 위한 복토재의 개선(2mm내외 사상)과 파종작업장치의 정확성이 요구되었다. 4. 파종작업 시 바람이 강하게 불 경우 사상규산질비료의 피복위치 불안정으로 이에 대한 보완대책이 요구되었다.

• Geomechanics and Engineering
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• 제28권5호
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• pp.521-529
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• 2022

This research work deals with the development of air pluviation method for preparing uniform sand specimens for conducting large scale laboratory testing. Simulating real field conditions and to get reliable results, air pluviation method is highly desirable. This paper presents a special technique called air pluviation or sand raining technique for achieving uniform relative density. The apparatus is accompanied by a hopper, shutters with different orifice sizes and numbers and set of sieves. Before using this apparatus, calibration curves are drawn for relative density against different height of fall (H) and shutter sizes. From these calibration curves, corresponding to the desired relative density of 60%, the shutter size of 13mm and height of fall of 457.2 mm, are selected and maintained throughout the pluviation process. The density obtained from the mobile pluviator is then verified using the Dynamic Cone Penetrometer (DCP) test where the soil is poured in the box using defined shutter size and fall height. The results obtained from the DCP test are averaged as 60±0.5 which was desirable. The mobile pluviator used in this research is also capable of obtaining relative densities up to 90%. The instrument is validated using experimental and numerical approach. In numerical study, Plaxis 3D software is used in which the soil mass is defined by 10-Node tetrahedral elements and 6-Node plate is used to simulate plate behavior in the validation phase. The results obtained from numerical approach were compared with that of experimental one which showed very close correlation.

• 한국CDE학회논문집
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• 제13권5호
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• pp.362-371
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• 2008

Generally, a PLM education program in university consists of lectures of theory, software lab and software development raining as an advanced subject. Most industries want more than these, such as practical problem solving capabilities, teamwork skills and engineering communications including human relationship, rhetoric, technical writing, presentation and etc. Problem-Based Learning is a problem-stimulated and student-centered teaming method, and an innovative education strategy for collaborative and self-directed learning by applying real world problems. Education paradigm changes from "teaching" to "learning" accomplished by team working, and students are encouraged to develop, present, explain and defense their ideas, suggestions or solutions of a problem, and the "cooperative teaming" proceeds spontaneously during team operations. Co-operative education program is an into-grated academic model and a structured educational program combining classroom learning with productive work experience in a field related to a student's academic or career goals. Based on the partnership between academic institutions and industries, students are engaged in real and productive "work" in the industry, in contrast with merely observing. In this paper, PBL with Co-op program is suggested as an effective approach for PLM education, and we made and operated a PBL-based education course with industry co-op program. The Co-op education in industry accompanied with the PBL course in university can improve practical problem solving capabilities of students, including modeling and management of P3R(Product, Process, resource and Plant) using commercial PLM software tools. By the result, we found this to be an effective strategy for helping students, professors and industries succeed in engineering education, especially PLM area.

• 한국수자원학회논문집
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• 제42권11호
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• pp.933-951
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• 2009

지구온난화에 따른 기후변화가 우리나라의 물순환 과정에 영향을 미칠 수 있다. 강우는 여러 기상인자들과 복잡한 영향을 주고 받으며 발생한다. 따라서 강우는 물순환 과정에서 기후변화에 따른 영향을 크게 받는 인자 중의 하나이다. 본 연구에서는 강우특성을 나타낼 수 있는 여러 시계열 자료를 구축하였다. 또한 강우의 발생 시계열을 연별, 계절별 및 월별로 구성하여 분석하였다. 분석 방법은 시계열 자료의 평균과 표준편차의 변동성 분석과 경향성 분석을 수행하였다. 또한, 최근 10년 동안에 강우특성의 변화에 대한 상대오차를 계산하여 과거 자료들과 비교하였다. 분석 결과에서 강우자료의 고유 특성인 무작위성에 의하여 뚜렷한 통계적 결과는 나타나지 않았다. 그러나 일반적으로 최근 10년간 강우량은 증가하였으며, 강우일수는 감소하는 추세를 보였다. 또한, 계절별과 월별에 따른 강우특성의 변화가 다르게 나타나고 있음을 확인할 수 있다.

• 한국도시환경학회지
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• 제18권4호
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• pp.465-471
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• 2018

본 연구에서는 축산계 현장정밀조사를 통해 정부공식 자료로 사용되고 있는 전국오염원조사 결과의 정확성을 확인하고 이에 기초하여 합리적인 가축분뇨관리방안을 제시하였다. 양쪽의 조사결과는 가축사육시설수에서 17.7%, 젓소사육두수에서 39.6%, 돼지분뇨 처리방법에서 41.6%로 가장 큰 차이를 나타냈다. 가축분뇨처리에서 가장 문제가 되고 있는 돼지의 경우가 가장 큰 차이를 보이는 주요 이유는 농경지 단위면적당 퇴비 사용량에 대한 법적 기준이 없어 개별처리 대상 농경지(과수원 포함)의 상당수가 위탁처리비의 절감을 위해 가축분뇨 매립장의 역할을 하고 있기 때문인 것으로 추정할 수 있다. 한편 하천인근의 농경지에 야적되어 있는 방치축분의 67%가 비가림 시설이 없어 비가 올 경우에 방치축분 더미가 그대로 하천으로 흘러 들어갈 수 있었다.