• Korean Journal of Construction Engineering and Management
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• v.8 no.5
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• pp.119-131
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• 2007

Design build (DB) is a construction project delivery system which has become one of the favored ones and the growth of DB by the public agencies has been steadily increasing. DB can be viewed as an evolutionary project delivery system, since DB project team members collaborate on work with each other, keep seeking cost effective and innovative alternatives that meet the construction needs of the project. Thus DB outperformed others in delivery speed, cost saving, and turnover quality. In Korea, DB projects likewise have steadily increased that it is needed to analyze characteristics of DB delivery system in Korea. For that purpose, this research would offer an analysis of characteristics of DB delivery system in Korea using system dynamics model with investigating the public market trend, comparing DB performance to DBB, and analyzing questionnaire survey.

• Korean Journal of Construction Engineering and Management
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• v.4 no.1 s.13
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• pp.90-96
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• 2003

The purpose of this study is to present an improvement building construction process by using prefabricated materials. The current slab form work has waste factor by unnecessary process and not complete integration with the finishing process. Therefore the study used value stream analysis methodology for effective improvement of slab form work process. The main contents of the study are as follows; 1) Non-value adding activities were found at existing slab form work process by current state mapping(CSM) 2) Future state mapping(FSM) suggest process Integration to slab form work. 3) Slab form work is analyzed reduction time-cost by prefabricated material. The study recommends that, as a future research, development of tool and technique for the non-value adding activities are eliminated in building construction and application of prefabricated material should be increased.

• Korean Journal of Construction Engineering and Management
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• v.23 no.5
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• pp.34-42
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• 2022

Construction site layout is attracting attention as efficient use of construction site space greatly affects the duration and cost of the overall construction. Therefore, there are many studies that automate and optimize construction site layout planning. However, the usability of construction site, which consists of goal variables of the studies, has still been unknown. Therefore, the authors present the evaluation criteria for usability of construction site layout and evaluate the usability of domestic construction sites through user survey. Furthermore, the difference in usability between construction site managers and construction site workers was confirmed. As a result of the survey, domestic construction site layout had a low effectiveness and had the lowest score in the environment category. In addition, construction site workers scored lower overall than construction site managers. Through such usability evaluation results, it contributed to the construction site layout theory by assessing current construction site layout practice and suggesting an improvement direction for automating site layout planning.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.198-203
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• 2020

Cracking due to material behavior like drying shrinkage easily occurs since tensile strength in concrete is very low at initial curing stage. In this paper, workability such as air content and slump was evaluated on CFC(Cellulose Fiber Concrete) with 0.0 ~ 2.0% of fiber addition, and the tests for tensile/compressive strength were performed. With increasing addition ratio of fiber, air content and slump kept similar level to 1.0kg/㎥ of addition ratio, and this trend was effective to 2 hours after mixing. Strength was enhanced with increasing addition ratio, which showed 7.0 ~ 9.0% for compressive strength and 7.0 ~ 22.0% for tensile strength, respectively. The tensile strength increased relatively more, which show the addition of cellulose fiber was very effective to crack resistance. The workability in CFC can be guaranteed for 2 hours in the following conditions like 2 minutes of mixing period and 1.0kg/㎥ of addition ratio of fiber.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.61-61
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• 2021

온도 성층화는 많은 저수지와 댐에서 흔히 발생하는 현상으로 호수나 저수지의 표면 온도가 바닥보다 상대적으로 높아 깊이에 따른 열 구배를 나타낸다. 이러한 온도 성층화 현상은 여름철과 같이 상부와 하부의 온도 차가 클수록 안정적이게 나타나며 이러한 층화 현상으로 수직 확산이 제어되어 수질에 영향을 미친다고 알려져 있다. 따라서 댐이나 호수 등 층화 현상이 심한 유체 내부 바닥에 물순환장치를 설치하여 외부로부터 공기를 끌어와 하부에서 공기를 분출하여 온도 성층을 약화시키기도 한다. 물순환 장치를 설비하면 수체의 혼합이 용이해지며 물질전달이 개선되어 수질이 향상된다. 국내의 경우 대청댐, 보령댐, 영주 댐 등 많은 국내 댐 내부에 물순환장치가 설비되어있다. 본 연구에서 댐의 물순환장치의 성능을 파악하기 위해 산기식 물순환 장비가 설치되어있는 영주댐을 연구 대상 지역으로 잡았다. 연구지역의 계절별 성층구조 및 특성을 조사하기 위해, 봄, 여름, 가을 영주댐에 방문하여 관측 자료를 취득하였으며 물순환 장치는 봄철의 경우만 가동하였다. 봄철의 물순환 장치 가동 전후 관측 데이터를 바탕으로 수치모형실험을 실행하여 관측 결과와 비교 및 검증하였다. 이를 바탕으로 여름, 가을에 물순환장치를 가동하였을 경우 댐 내부 수체의 혼합과정을 살펴보는 연구를 진행하였다. 본 연구는 CFD (Computational Fluid Dynamic) 시뮬레이션을 수행하기 위해 오픈 소스 소프트웨어 OpenFOAM(version 4.0)에서 열 전달이 포함되어있는 비압축성 VOF 솔버를 사용하였다. 본 솔버는 물과 공기를 동시에 나타낼 수 있으며 온도의 확산 방정식을 포함하고 있다. 또한 유동해석 수행 시 사용한 물순환장치의 효울은 실제 장치의 효율과 동일하다. 본 연구의 목표는 다음과 같다. (1) 관측만으로 파악하기 어려운 수체의 혼합거동을 유동해석 자료를 통해 면밀히 살펴보고 (2) 봄철 물순환 장치가 작동하기 전후 자료를 바탕으로 여름 및 가을철 물순환장치 가동 전후 데이터를 유동해석 자료로 취득한다. (3) 또한 물순환장치 가동 전후 데이터를 통해 계절별 혼합 효율을 취득한다.

• Proceedings of the KOR-KST Conference
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• 1998.10b
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• pp.453-453
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• 1998

우리나라가 관할하는 공역의 넓이는 약 40만$\textrm{km}^2$로 주한미군이 1952년부터, 국방부가 1958년부터 관리해 오다가 1995년에 건설교통부가 공역관리 업무를 인수하였다. 우리나라의 공역(대구 FIR)에는 비행금지구역, 비행제한구역, 위험구역, 경제구역, 훈련구역, 군작전구역 등 무려 114개의 특수목적 공역이 설정되어 있어 민항공기의 운항이 자유롭지 못하다. 또한 내륙을 중심으로 14개의 접근관제규역이 설정되어 있고 각기 관할구역에 대하여 배타적인 권리를 행사함으로써 신공항건설에 따라 운항이 필요한 소요공역 확보에도 애로가 많은 실정이다. 항로는 국내항로 5개, 국제항로 11개 등 모두 16개의 항로를 운영하고 있으나 대부분 한 개의 항로를 양방향으로 운영하고 있어 교통량 처리가 어려운 실정이고 항공교통량 전체의 75%가 수도권으로 집중되는 현상이 나타나 안전도 확보에도 지장을 주고 있다. 우리나라는 군사적 특수성 때문에 군의 작전비행 활동이 상당히 많으나 관제 및 비행절차에 관한 규정을 군과 민이 각각 달리 운영하고 있는 문제점들이 있다. 금번 세미나에서는 군의 작전활동을 유지하면서 민 항공의 안전성, 경제성 등을 확보하기 위하여 1)국제민간항공기가 제정한 공역등급화(ATS Air Space Spacification)방안, 2)접근관제구역의 조정개선 방안 3)특수공역의 합리적 운영방안, 4)항로의 적선화, 복수의 일방통행 항로 확보 및 국제연결 항로의 다양한 방안, 5)군민간의 관제규정의 일원화 방안 등을 제안하고자 한다.

• Korean Journal of Construction Engineering and Management
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• v.9 no.5
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• pp.186-193
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• 2008

The SPS, Strut as a Permanent System, method is widely adopted for the main structural member in addition to temporary strut function for the shuttering of excavation work. Although the SPS method has contributed to cost saving, time reduction, enhancement of structural stability, improvement of construction environment and so on at the building construction site, it caused the problems of increase of basement height and additional work for fire protection of steel structure. The increase of basement height caused the increase of shuttering depth and excavation, and the fire protection caused the additional cost as well as the deterioration of construction environment. In order to improve the problems, this paper is to propose a modularized hybrid structural system(HSD). The detail of the system is introduced and the structural performance and constructibility are proved through the experiment and site application.

• Korean Journal of Construction Engineering and Management
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• v.1 no.1 s.1
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• pp.35-44
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• 2000

The major objective of construction process control(CPC) is to provide construction managers with operational information that will help reduce project duration and save project cost. However, the CPC in Korea is being applied to construction projects with some basic problems such as the inconvenience of CPC S/Ws and the process control unconcerned with construction information classification system and computer system to integrate cost and schedule. This study analyzes the present condition of CPC including the basic problems, and then suggests the reform measures in technical and operational viewpoints to reduce construction risk. The focus of study is on the technical improvement for the application of construction information management system applicable to both cost estimating and schedule management.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.278-281
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• 2008

As all industries field has changed very quickly, the field of construction faces in many changed. It is the representatively change that focus on the growth of quality level than increase of the quantity in construction. Whether the project successes or not is related to the survival of the company and it is necessity that we need performance measurement indicators to complete the project successfully. The domestic construction company considers overbearingly the cost-performance indicator in executing a project so far. It is rare of studies that suggest the methodology of more deeply measurement and analysis about the each project itself. The performance measured methodology based on Lean Construction is linked with the each project performance measurement methodology. This methodology uses three indicators such as the reliability, effectiveness and productivity at the sane their measuring whether each task is completed at the point of work. The measurement on the three performance indicators measure and evaluate whether the task is completed on the focus of construction duration. The research suggest the work plan reliability and weight of the performance measurement methodology based on the Lean Construction and the three considerately in the scope of measurement. If the suggestion is considered fully, we can indicate more objective and accurate construction project performance measurement indicators based on Lena Construction.

• Korean Journal of Construction Engineering and Management
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• v.18 no.2
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• pp.30-37
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• 2017

In Korea, additional indirect costs generated from the time period extension of public construction projects have been studied. Practical claims against such costs are increasing. There are no clear criteria for calculating the delay cost caused by the extension, and thus calculation methods differ across entities. Logical valid calculation methods have also not been researched. Further, there are no Korean studies on the additional indirect cost caused by a suspension in a public construction project on a long-term continuing contract. The purpose of this research is to propose a method of calculating the indirect cost incurred by construction time extension that reflects the characteristics of Korean public construction projects. The cost patterns generated during construction periods were analyzed, and then the current criteria of calculating the indirect costs caused by the extension were examined. Following this, actual conditions and practices in the field were surveyed and the current calculation method was applied to a model case to compare the actual cost and that determined from the current calculation method. Issues with the current method were identified by this comparison. Based on this, this research proposes a method of calculating the total actual cost caused by a suspension in a public construction project that is appropriate for calculating the additional indirect cost generated by a suspension in a public construction project on a long-term continuing contract.