• 한국지반공학회논문집
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• 제19권5호
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• pp.199-210
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• 2003

흙이 변형하는 동안 전단지역 내에서 변형국지화가 자주 관찰된다. 사실상, 그 현상은 예외적이라기보다는 전형적으로 보인다. 개념적으로, 행해진 일의 증가가 음인 경우 변형국지화가 쉽게 발생한다. 이러한 현상을 검증하기 위해서, 본 연구에서는 배수상태의 조밀한 흙, 비배수상태의 느슨한 흙, 비배수전단하의 조밀한 흙에서의 공동화, 비균질한 흙, 판상형의 입자로 된 흙에서의 입자배열, 입자 깨짐을 가지는 흙, 그리고 낮은 함수비나 약한 시멘트결합이 된 흙 등 다양한 흙과 다양한 조건에 대하여 조사를 수행하였다. 이러한 경우들의 각각을 독립적으로 시험할 수 있도록 시료를 제작하였고 실험절차를 구상하였다. 실험결과에 의하면, 최고점후 변형연화거동을 가지는 흙은 변형국지화, 전단대형성, 그리고 점진적 파괴가 되기 쉽다. 응력상태, 흙밀도, 흙입자의 고유적인 역학적$.$지형학적인 특성, 저함수비, 그리고 비균질성이 변형국지화를 일으키는데 공헌을 하였다. 국지화가 가능한 모든 경우들을 고려해 볼 때, 실내시험으로부터 한계상태정수를 결정하는 최선의 방법은 배수전단하의 느슨하고 균일한 포화시료를 사용하는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제57권4호
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• pp.717-731
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• 2016

In orthopedic surgery and more especially in total arthroplastie of hip, the fixing of the implants generally takes place essentially by means of constituted surgical polymer cement. The damage of this materiel led to the fatal rupture and thus loosening of the prosthesis in total hip, the effect of over loading as the case of tripping of the patient during walking is one of the parameters that led to the damage of this binder. From this phenomenon we supposed that a remain of bone is included in the cement implantation. The object of this work is to study the effect of this bony inclusion in the zones where the outside conditions (loads and geometric shapes) can provoke the fracture of the cement and therefore the aseptic lousing of the prosthesis. In this study it was assumed the presence of two bones -type inclusions in this material, one after we analyzed the effect of interaction between these two inclusions damage of damage to this material. One have modeled the damage in the cement around this bone inclusion and estimate the crack length from the damaged cement zone in the acetabulum using the finite element method, for every position of the implant under the extreme effort undergone by the prosthesis. We noted that the most intense stress position is around the sharp corner of the bone fragment and the higher level of damage leads directly the fracture of the total prosthesis of the hip.

• 전자공학회논문지SC
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• 제46권4호
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• pp.70-76
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• 2009

본 연구에서는 자동차 사고나 뇌졸중 둥에 의해 경추 이하의 마비나 손, 발 등의 움직임이 자유롭지 못한 사람들의 컴퓨터 사용을 돕고자 손이나 발을 이용하지 않고 머리의 움직임과 눈의 깜박임만으로 컴퓨터 마우스 제어가 가능한 장치를 제안하였다. 마우스의 위치는 각속도 센서를 이용하여 머리의 움직임으로 추정하고, 눈 깜빡임에 의한 클릭과 더블 클릭은 광센서의 시야를 방해하지 않는 위치에 장착하여 커 클위치와 이벤트를 검출하였다. 제안한 마우스의 공간 이동 능력과 이벤트 검출을 비교한 실험에서는 좌우, 상하 이동은 기존 마우스와 비교하여 속도 면에서는 큰 차이는 없었으나, 정확도가 조금 떨어지는 이유로 인하여 정확한 위치로 이동시키는데 소요시간이 3$\sim$4배 정도 더 필요하였다. 데드 존을 갖는 비선형 상대 좌표계 방식을 이용하여 주기적으로 적분 에러를 제거해야 하는 문제를 해결하였고, 이동 거리와 속도를 함께 고려하여 직관적인 마우스 포인터 제어가 가능하도록 하였다. 주변광의 영향을 최소화하도록 광원 제어 회로를 설계하여 외부 광원의 변화에도 마우스 이벤트 검출이 영향을 받지 않았다.

• 한국정보통신학회논문지
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• 제18권4호
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• pp.913-919
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• 2014

본 연구는 지하공사에 적용되는 흙막이 공법 중 4개 공법을 대상으로 영향요인들의 상대적인 가중치를 분석하여 최적의 흙막이 공법을 선정하는 방법에 대한 연구이다. 도심지에 적합한 흙막이 공법 선정을 위한 주요 영향영역과 영향요인들을 설문조사를 통해 분석하여 이를 토대로 매트릭스 분석을 이용하여 흙막이 선정 방법을 제안하였고, 대안별 공법들을 대안 평가기준의 중요도를 통하여 가중치 및 대안 평가기준을 종합 분석함으로써 영향 영역들의 중요도를 평가하여 최적 대안을 분석하였다. 다양한 제한요소를 고려해야 하는 지하 흙막이 공법 선정을 위한 분석 시 IT분야의 정보처리기술과의 융합은 많은 제한조건을 체계적으로 분석하여 최적화하는데 효과적이다.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.15-26
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• 2014

This paper proposes a Modified Particle Swarm Optimization with Time Varying Acceleration Coefficients (MPSO-TVAC) for solving economic load dispatch (ELD) problem. Due to prohibited operating zones (POZ) and ramp rate limits of the practical generators, the ELD problems become nonlinear and nonconvex optimization problem. Furthermore, the ELD problem may be more complicated if transmission losses are considered. Particle swarm optimization (PSO) is one of the famous heuristic methods for solving nonconvex problems. However, this method may suffer to trap at local minima especially for multimodal problem. To improve the solution quality and robustness of PSO algorithm, a new best neighbour particle called 'rbest' is proposed. The rbest provides extra information for each particle that is randomly selected from other best particles in order to diversify the movement of particle and avoid premature convergence. The effectiveness of MPSO-TVAC algorithm is tested on different power systems with POZ, ramp-rate limits and transmission loss constraints. To validate the performances of the proposed algorithm, comparative studies have been carried out in terms of convergence characteristic, solution quality, computation time and robustness. Simulation results found that the proposed MPSO-TVAC algorithm has good solution quality and more robust than other methods reported in previous work.

• 한국재난정보학회 논문집
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• 제16권1호
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• pp.111-122
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• 2020

연구목적: 효율적인 급경사지관리를 위하여 급경사지 관리 절차의 문제점을 진단하고 개선된 프레임워크를 제안을 통해 인명 및 재산피해를 경감하고자 함에 있다. 연구방법: 붕괴위험지역 지정 절차검토, 지자체 인터뷰, 전문가 자문을 통해 급경사지 관리 전반적 문제점을 도출함 연구결과: 평가 전 선정단계, 관리의 주체, 관리 방법과 관리 단계별 개선되어야 할 요소들을 도출하였다. 결론: 본논문은 제기된 문제점을 확인하여 개선점을 도출하였고 새로운 시스템(안), 급경사지 발전을 위한 연구 방향을 제시하였다.

• Journal of Biosystems Engineering
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• 제29권3호
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• pp.207-216
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• 2004

This study was intended to investigate the characteristics of ride vibrations transmitted to tractor operator during rotary tillage and plowing operations. Seat accelerations of a 41 ps diesel tractor in rotary tillage and plowing were measured and evaluated as specified in the ISO 2631-1. Effects of working speed and tilling depth on ride vibration were investigated. The level of ride vibration was also evaluated in terms of health guidance caution zones. Some of the results of the study are as follows: 1. The level of ride vibration in plowing was about 4.3 times greater than in rotary tillage. 2. The effect of working speed in rotary tillage differs depending upon the tillage depth. The level of ride vibration was increased with the speed, but it decreased over a certain tillage depth. Fore and aft vibration was 2.2-2.7 times severer than horizontal and vertical vibrations. Dominant frequency band was 1-3.15 ㎐ in fore and aft, 1-3.15㎐ and 16-25㎐ in horizontal, and 16-25㎐ in vertical directions. 3. Plowing reduced the ride vibration by 42.8-50.2%. But its positive effect decreased as the plowing speed increased. In plowing operation, ride vibration was similar degrees in fore and aft, horizontal and vertical directions. The dominant frequency band in plowing operation was 1-2.5㎐ in fore and aft, 1-2.5㎐ in horizontal, and 1-8㎐ in vertical directions. 4. On a basis of daily work hours of 4, total level of ride vibrations in plowing operation is likely to be harmful to operator's health.

• 한국환경복원기술학회지
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• 제10권2호
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• pp.71-83
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• 2007

This study aims to provide basic data for planning the supply and demand of urban parks and setting up facilities in urban parks that reflect the use patterns of visitors. The study was conducted by surveying the total number of urban park users and the number of users for different time zones and analyzing their use patterns through on-site surveys at 17 urban parks located in seven cities/counties in Gyeonggi province. The result showed that as for distribution of urban park users by time zone, the number of users was highest in the afternoon. Between 7 and 9 o'clock in the morning in weekdays, many users came to urban parks for their morning exercises. There was hardly no difference between male and female. When the number of users of 17 urban parks was surveyed, a park was used by 734 people per day on weekdays in average. When the total number of users per year was estimated, a resident nearby a park visited the place 4.7 times a year in average. In addition, the analysis showed that the number of users of man-made parks was twice as high as that of natural parks. The number of users did not vary depending on the size of a park. As for use patterns by time zone, no difference was found in activity types between parks larger than 100,000 $m^2$ and those less than 100,000 $m^2$. Usually, in the morning, users came for exercises In the afternoon, users visited the parks for more diverse purposes. In the evening, they tended to visit parks to work out and wrap up a day. Going forward, the outcome of this study should be utilized as important data for analyzing the demand and supply of urban parks. In addition, the number of users by time zone and their use patterns should be fully considered when introducing facilities in parks.

• 대한조선학회논문집
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• 제50권5호
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• pp.334-342
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• 2013

In this paper, we analyze the procedure of the design manager for the enhancement of the hull production design process by use of the simulation method. Normally, design manager assigns design jobs according to various methods and estimates the corresponding results. When the construction drawing which is the output of the detail design where a design is dealt by zones, the design manager identifies blocks and analyzes their work difficulties, and assigns jobs to design engineers who are different in capabilities. These processes including the design engineer who can be modeled with man-hours evaluation model are represented in detail as a simulation model. As the high-level modeling for the discrete-event system, we use Event Graph model. And we implemented the simulation using Simkit which is open simulation engine for the discrete-event system. We made the simulation scenario to be written by a user in the scenario generator which is separated from the simulation model, and made the simulation result to be visualized in the form of Gantt chart in a Web. In the scenario of the irregular issuance for various construction drawings which contain different numbers of blocks, we performed the Monte-Carlo simulation according to various assignment methods to find the assignment result that satisfies the mid-term schedule.

• 한국환경과학회지
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• 제16권6호
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• pp.735-743
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• 2007

A grouting method is the way to effectively prevent pollutants from spreading into the ground during the digging process of groundwater. This study, based on the comparative study of grouting methods being generally accepted, suggests various construction methods which are suitable for geological structure as follows: In Jeju Island, it is very likely that rocks may fall in shuttered zones such as cracks, joints, scoria layers, and clinker layers. For this reason, it is recommended that materials be injected from the bottom toward the top, not from the top to the bottom. In the case where the amount of injected materials become too large in the areas of cracks or joints because of high level of permeability coefficient, grouting materials which smeared into surrounding areas may cause unwanted cut in the aquifer of the bottom level. To avoid this, the amount of water should be reduced from the typical water-cement ratio of 1:2, and grouting materials with larger grading should be used. If the deep excavation of ground is made in Jeju Island, it is likely to have lots of voids because of geological characteristics. Based on the results of this research, it is found that to construct interior casing, the centralizer should be attached to the casing to prevent the casing from being in contact with the counter fort. The grouting in Jeju Island should be thicker than usual. To avoid over-use of grouting materials, to prevent grouting in more than necessary zone, and to facilitate grouting of void areas, the flexible selection of materials is required. And, to exactly figure out the interior of dug well, an examination through CCTV should necessarily be performed when grouting work is in progress.