• 대한전자공학회논문지
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• 제14권3호
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• pp.18-24
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• 1977

본 논문은 FET의 핀치오프특성을 이용하여 직렬인버어터회로를 구성하고 그것의 출력특성을 게이트바이어스 주파수 및 부하의 변동에 따라 분석하였다. 상기 회로는 SCR직렬인버어터회로에서 생기기 쉬운 게이트바이어스주파수 및 부하의 변동에 따른 출력의 불안정을 제거하였다. 그러나 FET직렬인버어터의 전류용량이 적어 경부하에 적당하다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 추계 학술발표회
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• pp.490-496
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• 2006

In order to design accurately plastic board drain (PBB) method, it is important to determine the equivalent circle of PBD. In this paper, a series of numerical analyses on soft ground improved by PBD were carried out, in order to investigate the resonable equivalent circle of PBD considering consolidation behavior of improved soft ground by PBD. The applicability of numerical analyses, in which an elasto-viscoplastic three-dimensional consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of soft ground improved by PBD. And, through the results of the numerical analyses, consolidation behaviors of soft ground during consolidation was elucidated, together with the equivalent circle of PBD considering consolidation behaviors.

• 지질공학
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• 제23권2호
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• pp.105-115
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• 2013

보의 건설 및 하천 단면의 증가는 하천 수위 상승과 호우기 유출량의 증가를 가져왔다. 낙동강 중하류에 설치된 23개의 지하수 관측망 지하수위 자료를 사용하여 보 담수 전후의 지하수위 시계열 변동 유형의 변화를 분석하였다. 월평균 지하수위 자료를 토대로 담수 전후의 지하수위를 비교한 결과 보의 직상류 주변 지역에서 지하수위 변동이 가장 크게 나타났으며, 8월의 경우 하천 수위 조절 효과로 월평균 지하수위가 0.1 m 감소하였으나 10월에는 1.3 m 상승한 것으로 나타났다. 지하수위 시계열 자료와 하천 수위 자료를 사용하여 군집분석을 실시한 결과, 담수 이전에는 7개 지하수 관측망의 자료가 하천 수위와 유사성 거리가 가까운 그룹이었으나, 담수 이후에는 14개로 증가하여 하천 수위와 유사한 그룹의 범위가 넓어졌다. 지하수위 시계열에 대한 주성분분석 결과, 담수 이전에는 하천 변동성을 대표하는 주성분(주성분 1과 주성분 2)의 설명력이 총 82%이었으나, 담수 이후에는 하천 변동성을 설명하는 주성분(주성분 1)의 설명력이 45%로 줄어들어 지하수위 자료를 설명하는데 하천 요인의 기여도가 줄고 인위적인 양수 등과 같은 기타 요인의 기여도가 높아졌다. 이와 같이 변화되는 수문 환경에 대비하여 지속적인 조사 및 관측이 필요하며, 하천 주변에서는 지표수와 연계되는 지하수 관리 정책이 수립될 필요가 있다.

• 한국수자원학회논문집
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• 제35권6호
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• pp.807-816
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• 2002

본 연구에서는 댐 건설에 따른 댐 하류 유황의 변화에 대해 살펴보고자 하였다. 이를 위해 대청댐이 위치해 있는 금강유역을 대상으로 하였으며, 댄 건설 전후의 인공위성 영상자료를 분석해서 댐 하류 수표면의 변화를 평가하였고, 유황변화에 대한 분석을 위해서는 대청댐 하류에 위치한 공주 수위관측소의 자료를 이용해서 댐의 건설에 따른 하류 유황변화를 분석을 실시하고 그 영향을 평가하였다. 또한, 댐의 홍수조절에 따른 홍수량 규모의 변화를 살펴보기 위해 대청댐 하류의 공주와 규암지점의 연 초과치 계열에 대한 빈도해석을 실시하고 그 변화를 분석하였다. 이를 통해 댐이 하류하천의 유황을 개선하고 일정하게 유지해서 안정적인 수자원 공급을 가능하게 해주는 역할과 첨두유량의 감소로 홍수피해를 저감시켜주는 역할을 동시에 담당하고 있음을 알 수 있었으며, 수자원의 관리 및 이용측면에서 이·치수에 기여하는 댐의 긍정적인 효과를 다시 한번 확인할 수 있었다.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1140-1147
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• 2009

Productivity measurement of construction machinery is a significant issue faced by many contractors especially those involved in earthwork projects. Traditionally, equipment production rate has been estimated using data available in manufacturers' catalogues, results of previous construction projects, or personal experience and assessments of the site personnel. Actual production rates obtained after the completion of a project demonstrate the fact that most of these methods fail to provide accurate results and as a direct consequence, may lead to unrealistic project cost estimations prepared by the contractors. What makes this more critical is that in most cases, inadequate cost estimations lead the entire project to exceed the initial budget or fall behind the schedule. In this paper, a linear regression method to estimate bulldozer productivity is introduced. This method has been developed using SPSS-16 software package. The presented method is used to estimate the productivity of Komatsu D-155A1 series which is commonly used in many earthmoving operations in Iran. The data required for the numerical analysis has been collected from actual site observation and productivity measurement of 60 pieces of D-155A1 series currently being used in several earthmoving projects in Iran. Comparative analysis of the output data of the presented regression method and the existing productivity tables provided by the manufacturer shows that when compared to the actual productivity data collected on the jobsite, a significant increase in accuracy and a remarkable reduction of data variance can be achieved by using the presented regression method.

• 국제학술발표논문집
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• The 8th International Conference on Construction Engineering and Project Management
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• pp.63-74
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• 2020

The assembly of modular construction requires a series of thoroughly-considered decisions for crane lifting including the crane model selection, crane location planning, and lift path planning. Traditionally, this decision-making process is empirical and time-consuming, requiring significant human inputs. Recently, research efforts have been dedicated to improving lift planning practices by leveraging cutting-edge technologies such as automated data acquisition, Building Information Modelling (BIM) and computational algorithms. It has been demonstrated that these technologies have advanced lift planning to some degree. However, the advancements tend to be fragmented and isolated. There are two hurdles prevented a systematic improvement of lift planning practices. First, the lack of formalized lift planning workflow, outlining the procedure and necessary information. Secondly, there is also an absence of a shared information environment, enabling storages, updates and the distribution of information to stakeholders in a timely manner. Thus, this paper aims to overcome the hurdles. The study starts with a literature review in combination with document analysis, enabling the initial workflow and information flow. These were contextualised through a series of interviews with Australian practitioners in the crane-related industry, and systematically analysed and schematically validated through an expert panel. Findings included formalized workflow and corresponding information exchanges in a traditional lift planning practice via a Business Process Model and Notation (BPMN). The traditional practice is thus reviewed to identify opportunities for further enhancements. Finally, a BIM-based lift planning workflow is proposed, which integrates the scattered technologies (e.g. BIM and computational algorithms) with the aim of supporting lift planning automation. The resulting framework is setting out procedures that need to be developed and the potential obstacles towards automated lift planning are identified.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2009년도 정기 학술발표대회
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• pp.153.2-153.2
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• 2009

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.279-284
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• 2002

Prestressed concrete(PSC) bridge structures with a number of continuous spans has been segmentally built in many countries. These methods include incremental launching method, movable scaffolding method, full staging method and balanced cantilever method. In these segmentally constructed prestressed concrete bridges, many construction joints exist and these construction joints are weak points in PSC bridges. The prestress force can be introduced prestress force continuously through the construction joints of PSC bridge superstructure using tendon couplers. The main objective of this study is to evaluate the structural behavior and ultimate flexural strength of construction joints in PSC girder bridge members. To this end, a comprehensive experimental program has been set up and a series of full-scale tests have been performed. Ultimate flexural strength of construction joint in PSC members with tendon couplers is decreased by approximately 10% for non-coupled members.

• KIEAE Journal
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• 제13권2호
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• pp.33-38
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• 2013

Limited resources for construction material in the Mae-Hae region, a remote Northern Thailand, acted as an impetus to introduce a new way for constructing their dwellings. The new construction material brought new construction methodology, namely, using earth and bamboo which are indigenous materials, readily available for them to use. Using indigenous material at Mae-Hae region was most ecological and logical method for establishing sustainable dwellings both in terms of monetary and ecological reasons. Prior to the construction at Mae-Hae, Thailand, series of experimental tests on the strength of rammed earth were performed off site at our university and also brought soil samples from the actual job site at Mae-Hae for detailed soil analysis. Through the tests, integrity of the earth and characteristics of the soil were established to build a small senior citizen center as an example. This appropriate technology is expected to contribute to the sustainable construction at Mae-Hae.

• 한국안전학회지
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• 제11권1호
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• pp.108-120
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• 1996

It is a problems in industrial accidents that the knowledge for industrial accidents is obtained by experience, not by experiment. This experiential knowledge is obtained by Investigating accident cases and utilizing those for safety education. Therefore, in this paper, the situation about the serious accident of construction is analyzed by occupation, a kind of construction, time group, season, type of accident, and accidental cause. And the mutual · relations of these factors are studied. The most frequent type of the serious accidents of construction Is the falling accident. It happenes most frequently at apartment construction among kinds of construction and to structural worker, finishing worker, normal worker in order among occupations. And it is found that the most critical causes of the falling accident are the imperfection of safety facilities and unwearing of protection equipments, so a number of accidents can be reduced by the expansion of safety facilities and wearing of protection equipments absolutely. The counterplan of prohibition of accidents and the direction of government policy are presented by a series of nalyses for accident cases.