• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.114-119
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• 2004

Endbeam is an important structural member of freight bogie for the support of service loading. In general, more than 25 years' durability is necessary. However, endbeam occur fatigue fracture in dynamic stress concentration location because comparatively strength and stiffness are low. Therefore, structure analysis is performed to evaluate structural problem of endbeam and local strain range as durability analysis. The number of cycles is extracted concerning the bogie in operation by measurement dynamic stress time history on critical part which is crack initiation in actual fact. At this time rainflow cycle counting is used to consider change of stress for operating condition. Based on the fatigue life curves and the stress analysis, the fatigue life of the endbeam is predicted and compared with the experimentally determined fatigue life, resulting in a fairly good correlation.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 춘계학술대회
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• pp.491-494
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• 2018

넓은 지역에 광범위하게 분포되어 있는 통신용 무선기지국은 관리에 많은 어려움이 있다. 특히 산간 오지에 있는 무인 통신무선 기지국은 위급한 상황 발생시에 접근에 많은 어려움을 겪고 있다. 대형 통신회사들은 송수신 정보만 원격으로 관리하고 있고 실제 시설 유지를 책임지고 있는 지역 중소기업 협력업체들은 이러한 기술을 보유하고 있지 않아서 일일이 현장 방문을 통하여 확인하고 있는 실정이다. 본 연구에서는 넓은 범위에 산재해 있는 무선기지국내의 온도, 습도, 화염 발생여부, 전원 동작 여부를 실시간으로 모니터링하여 클라우드 서버에 보내 사무실에서 실시간 모니터링을 통하여 관리 및 위급시 경고 메시지 전송 등이 수행이 가능한 시스템을 클라우스 서버 구축을 통하여 IoT 센서 기술을 이용하여 구현한 내용을 제시하고자 한다.

• 상하수도학회지
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• 제24권1호
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• pp.73-83
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• 2010

This study was performed to increase the removal efficiency of the biofilter packed with granular sulfur in municipal wastewater reclamation facility. Constituent units were influent water tank, denitrification tank, BOD reduction tank and outlet. And, the major operation factor is a biofilter packed with submerged granular sulfur. Actual wastewater and synthetic wastewater were used as influent wastewater. Experimental condition was divided into two phases according to the amount of a phosphorus coagulant. Total phosphorus removal efficiency was insignificant at mode I that phosphorus coagulant was not injected. The average influent and effluent total phosphorus concentrations at mode II were 0.5 ~ 1.0 mg/L and 0.27 mg/L, respectively. As for COD and BOD effluent concentrations, COD was 3.0 mg/L and BOD was 1.0 mg/L. Additionally, nitrogen removal rates were high at low influent DO concentration. In conclusion, a new process, biofilter packed with granular sulfur is expected to treat high-rate nitrogen wastewater and expected to be utilized as an alternative of technological innovation for the nitrogen treatment.

• 한국소음진동공학회논문집
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• 제27권2호
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• pp.204-212
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• 2017

The rotor dynamics and balancing technic for rotating equipment during engineering and manufacture stage are to be carefully considered in order to minimize the operation troubles regarding vibration during commissioning stage. In this paper, the test rig, which includes the disks as balancing plane, is designed and manufactured, so that the characteristic of rotor dynamics can be analyzed such as critical speed and mode shape. The critical speed predicted through natural frequency analysis is verified by the actual measurement on bearing housing vibration during start-up condition of test rig. The low speed balancing and the operating speed balancing test are performed respectively with consideration of first critical speed, and the residual unbalance amounts are estimated in accordance with the relevant method described in API standard. In addition, the single and dual plane balancing are carried out on main disk and trim disk depended on phase information at each balancing step.

• 한국건설관리학회논문집
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• 제5권2호
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• pp.123-135
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• 2004

건설공사에서 안전사고 예방을 위하여 안전조직, 교육, 점검과 평가에 많은 노력을 기울이고 있으나 안전사고가 감소하지 않고 있는 실정이다. 건설현장의 안전사고를 예방하기 위하여 안전관리자, 안전교육, 점검과 평가, 공정관리, 안전관리 체크리스트의 활용에 관한 실태조사를 실시하고 문제점을 분석하였다. 그에 따라 작업에 관한 안전관리 체크리스트를 상세하게 사전에 작성하여 전산화하고 부가적인 정보를 연계하여 활용도를 높이는 체크리스트 개선안을 제시하였다. 나아가 체크리스트와 공정표상의 작업과의 연계방법과 운영방법을 제시하여 체크리스트가 시간개념을 갖고 체계적으로 활용되어 안전사고를 예방할 수 있도록 하였다.

• 한국농촌건축학회논문집
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• 제6권2호
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• pp.1-10
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• 2004

The purpose of this study is to clarify the actual condition of the layout and floor planning of elementary schools for the 7th education curriculum. This article discuses about the basic characteristics of the plan composition and the outdoor spaces of 35 elementary schools in Gyeongnam prefecture. The results of this study are summarized as follows; 1) To respond to the 7th educational curriculum, unit classrooms need to be expanded or space for a multi-purpose room needs to be secured to serve the following purposes: the operation of educational program by the level and offering of unified Subjects. overall, elementary schools need to seek ways to deal with problems associated with space composition, types of classrooms, and changes in the number of classrooms so that the 7th Educational curriculum can be carried out smoothly. 2) Different from the past, various plan types are available nowadays. Even in case of schools with the same class size, their areas were different by 130 percentages or higher. Therefore, practicality needs to be more focused than facility standards in order for the school to cope with changes in future educational environment. 3) When designing the elementary school in the future, more space needs to be assigned for learning by expanding facilities - special purpose classrooms and supporting facilities - to accommodate students' various learning activities. In addition, faculty facilities need to be rearranged to promote research and development as well as to ensure the operation of the educational program. And, resident facilities that consider the close connection with the local community need to be rearranged in an efficient manner as well.

• 멤브레인
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• 제33권3호
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• pp.127-136
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• 2023

본 연구에서는 실리카 복합막 기반 고분자 전해질막을 5단 연료전지 스택에 적용하여 성능 평가를 수행하였다. 이를 통하여, 개별 구성 요소의 성능도 중요하지만, 전체적인 관점에서 공급되는 연료의 유량이 스택 성능에 중요한 역할을 하며, 특히 수소의 유량에 크게 의존한다는 사실이 확인하였다. 산소의 유량을 증가시켜도 성능의 변화는 미미한 반면, 수소의 유량을 증가시키면 성능이 향상되는 것을 확인하였다. 그러나 수소의 유량 증가는 수소와 산소 유량 비율의 불균형을 초래하여 장기적으로는 스택 성능과 내구성을 저하시키는 문제가 관찰되었다. 이러한 현상을 스택 구성 요소 및 개별 단위 셀에서도 관찰할 수 있었으며, 따라서 스택 운전 시 각 구성 요소의 성능을 최적화하는 것 외에도 균일한 유량 제어를 위해 유로 설계 및 운전 조건을 최적화하는 것이 중요하다는 것을 알 수 있었다. 마지막으로 실리카 복합막은 최대 출력 기준 25 W 이상의 성능을 나타내어 실제 연료전지 시스템에 적용하기에 충분한 성능을 갖춘 것으로 판단된다.

• Smart Structures and Systems
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• 제29권5호
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• pp.653-660
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• 2022

Gravel scattering that is generated during operation of high-speed railway vehicle is cause to damage of vehicle such as windows, axle protector and so on. Especially, those are frequently occurred in winter season when snow ice is generated easily. Above all, damage of vehicle windows has not only caused maintenance cost but also increased psychological anxiety of passengers. Various methods such as heating system using copper wire, heating jacket and heating air are applied to remove snow ice generated on the under-body of vehicle. However, the methods require much run-time and man power which can be low effectiveness of work. Therefore, this paper shows that large-area heating system was developed based on heating coat in order to fundamentally prevent snow ice damage on high-speed railway vehicle in the winter season. This system gives users high convenience because that can remotely control the heating system using IoT-based wireless communication. For evaluating the applicability to railroad sites, a field test on an actual high-speed railroad operation was conducted by applying these techniques to the brake cylinder of a high-speed railroad vehicle. From the results, it evaluated how input voltage and electric power per unit area of the heating specimen influences exothermic performance to draw the permit power condition for icing. In the future, if the system developed in the study is applied at the railroad site, it may be used as a technique for preventing all types of damages occurring due to snow ice in winter.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.2078-2087
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• 2010

본 연구는 수술환자의 타지역 의료이용과 관련된 요인을 규명하기 위하여 2004년부터 2006년도의 퇴원손상 환자조사뿐 아니라, 인구센서스 및 보건의료자원 실태조사자료를 이용하여 교차분석, 로지스틱 회귀분석을 실시한 결과 다음과 같다. 첫째, 수술환자의 의료이용은 수도권 중심으로 집중화 현상이 뚜렷하다. 이를 개선하기 위해서 정부에서는 의료기관 및 병상수를 공급하는 일 뿐만 아니라 의료의 지역화를 위해 지방에서의 의료의 질적 수준을 올리는 정책이 필요하다. 둘째, 눈 및 부속기 질환 및 암환자의 타지역 수술률이 높으므로 질병에 따른 의료의 지역화를 위한 특정 질환의 지역화 정책추진이 요구된다. 셋째, 산재환자 수술환자의 타지역 진료율이 시간이 갈수록 증가하므로 손상환자를 위한 지역화 정책도 필요하다 할 것이다.

• 한국초지조사료학회지
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• 제25권1호
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• pp.65-70
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• 2005

This study was conducted to investigate the effect of combine crawler attaching slurry spreader on soil and growth of rye. The performance test at actual field was conducted to test for possibility of practical use. Field test of the slurry spreader was operated in upland and paddy field. Experiments was conducted to compare the effects of the soil damage and crop productivity incorporating Pig slurry by two different types of slurry spreader. In this experiment a slurry spreader using crawler of combine have been designed and developed to enhance the operation in small field and reduce e damage of soil structure. but it was not suitable for transference in long distance. Conventional tractor mounted vacuum is not suitable for $71.6\%$ water condition in the small areas of paddy land. But the slurry spreader using crawler could be controlled the working point and moving by crawler in paddy land of small area. The wheels depths of soil in the supplementary application in the rye field was 4.9 m in tractor mounted spreader. but the wheels depth of crawler attaching spreader was 1.6cm. The dry matter yield of rye was reduced by $12\%$ in supplementary application of slurry due to mechanical damage from passage of the tires. This is particularly noticeable at high soil moisture condition in paddy land. It was concluded that the slurry spreader developed in this study could be successfully used for basal and supplementary application of slurry in rye paddy field.