Identification of Factors Driving Crew Production Rate : Methodology and Application

허영기,Huh Youngki Korea Institute of Construction Engineering and Ma 2004 건설관리 : 한국건설관리학회 학회지 Vol.5 No.5

For accurate construction contract time estimation, few parameters are more significant than crew production rates and factors affecting the rates. However, statistical analysis techniques for finding such factors are not always simple mainly because there are many factors and the interaction between factors is not well quantitatively understood. This paper presents methodology of identifying factors driving crew production rates. The methodology is further demonstrated with representative data collected by the author from 13 on-going highway constructions. Three factors were identified as statistically significant drivers of Cap crew production rate: 'Cap Size (m3/ea)'; 'Cap Length (m)'; and 'Cap Shape (Rectangle vs. Inverted 'T')'. It was also found that the production rates are best explained by a multiple regression model with two of the drivers; 'Cap Size' and 'Cap Shape'.

노후화된 학교건물의 적정시설투자비 산정모델 적용사례

허영기,Huh, Young-Ki 한국교육녹색환경연구원 2011 교육·녹색환경연구 Vol.10 No.1

Area Offices of Education in Korea assign and execute government budget based on the evaluation of school buildings' safety rating and degree of their deterioration. However, it is never easy to estimate the most appropriate investment amount for old buildings under consideration of their service lives and residual values together. A model of estimating optimum investment cost for obsolete school building is developed taking its life cycle cost into account. The model is also applied to six old buildings in five different schools and found that some of the facilities hardly needed further investment and were better to be rebuilt. The study results will be a great beneficial for officers to make right decision on maintaining obsolete school buildings and to maximize tax payers' money.

Data Collection Methodology of Activity Production Rates for Contract Time Determination

허영기,김창완,송종철,Huh Youngki,Kim Changwan,Song Jongchul Korea Institute of Construction Engineering and Ma 2004 건설관리 : 한국건설관리학회 학회지 Vol.5 No.1

Contract time determination for highway construction projects has never been easy despite considerable research efforts from academia as well as industry. High variations in crew production rates are considered one of the main barriers to accurate contract time determination. This paper presents a methodology for collecting field information on crew production rates which will help to enhance the accuracy of contract time determination for highway bridge construction. Based on a standard data collection tool developed, data on field crew production rates was collected from 14 on going projects in Texas, USA, over the past two years. The production rates based on the data collected were considered by industry practitioners to be more realistic and practical than those available to the current practices. As more data becomes available, key drivers influencing production rates could be identified and provide site personnel with a means to better plan and control production in a project specific context.

Quantitative Analysis on Factors Affecting Crew Productivity : Crew Size

허영기,Huh Youngki Korea Institute of Construction Engineering and Ma 2004 건설관리 : 한국건설관리학회 학회지 Vol.5 No.3

Consideration of factors driving crew productivities is imperative for accurate construction time estimation. Their impacts need to be well understood by estimators. There have been, however, little studies that quantified relationships between crew productivities and factors. This paper quantifies impacts of $^{\circ}A$ECrew size $^{\circ}\phi$ on crew productivities, for three highway concrete bridge activities, namely Column, Cap, and Deck, based on data compiled from 17 on-going highway projects in Texas State, USA. It was found that, for Bridge Deck operation, an increase of one crew-worker of formwork and rebarwork by one, leads to an increase of the productivity (cy/crew day) by 2.5 and 2.9, respectively. For the other activities, larger crew sizes did not lead to better crew productivities.

표준품셈의 기계경비 산정 현실화를 위한 자료 조사.분석 -불도우저와 로우더를 중심으로-

허영기,김경아,안방률,태용호,박희성,김창완,Huh, Young-Ki,Kim, Kyung-A,Ahn, Bang-Ryul,Tae, Yong-Ho,Park, Hee-Sung,Kim, Chang-Wan 한국건설관리학회 2008 건설관리 : 한국건설관리학회 학회지 Vol.9 No.1

건설공사 표준품셈 기계경비 부분은 1960년대 초 일본 및 미국의 자료를 근간으로 하여 제정된 이후, 극히 부분적으로만 제 개정되었을 뿐 그 동안의 건설기계와 공법의 발전을 반영하지 못하고 있다. 본 연구에서는 합리적인 기계경비 산출을 위해 불도우저와 로우더를 중심으로 국내 외 문헌조사, 건설현장 16개소 실사, 그리고 건설기계장비 임대업체 20개사를 대상으로 설문조사 및 인터뷰를 실시하였다. 수집한 자료와 현행 표준품셈의 기계경비 산출에 적용되는 수치들을 비교 분석한 결과, 관리비는 금리와 보험료를 고려하여 6종건설기계와 일반기계를 구분하여 현실적인 수치를 제시하였으며; 운전경비는 조수를 삭제하는 것이 현실적인 것으로 나타났다. 또한 주연료 및 잡재료는 현행수준이 적정하지만 장비가격은 상향조정할 필요가 있는 것으로 분석되었다. 논문에서 제시하고 있는 각종 자료 및 수치들은 건설기계와 기술의 급속한 발전을 예정가격산정의 기준에 적용할 수 있는 기초가 될 수 있을 뿐 아니라, 관련 연구의 토대가 될 수 있으리라 기대한다. The Equipment Expenses section of the Poom-Saem that is used for Construction Cost Estimation of public sectors in Korea has been rarely revised, and so does not reflect changes of Construction Equipment technology and construction methods, since it was established based on data from Japan and the U.S in the early 1960s. In order to make reasonable estimation of equipment expenses for a bulldozer and a loader, the domestic and overseas documentary records were investigated. Further, 16 construction sites were visited, and 20 Construction Equipment leasing services were surveyed. The optimum level of each item which consists of equipment costs was revealed based on the result of the analysis on the figures of equipment costs calculation from the Poom-Saem and the collected data. The research will be the foundation for applying the rapid development of Construction Equipment and technology to the appropriate cost estimations and the ground work of related studies.

철골 공장제작의 노무생산성 및 간접비율 도출

허영기(Huh, Young-Ki),김경욱(Kim, Kyoung-Uk),김경원(Kim, Kyung-Won) 대한건축학회 2013 大韓建築學會論文集 : 構造系 Vol.29 No.6

Steel works, in a typical building project, consist of more than 20% of total construction cost, which makes it essential to estimate the appropriate level of steel works cost precisely. In order to draw direct labor productivity and indirect cost rates, theories of productivity and indirect cost were investigated, and recent field data were collected from steel factories. As a result, it was revealed that direct labor productivity of steel fabrication and welding were 1.00(person·day/ton), 0.35(person·day/ton), respectively. It was also found that the ratio of indirect labor productivity compared to the direct labor ratio was approximately 17% and the ratio of indirect cost compared to direct cost was approximately 93%. In addition, influence factor having an effect on indirect cost of the steel factories were analyzed using ANOVA. It was confirmed that ‘the way of subcontracting steel works’ and ‘location of steel factory’ had influence statistically on the indirect cost. The results will help industry professionals estimating labor productivity and indirect cost of a steel factory, as well as a construction project.

원자력발전소 철근콘크리트 공종의 작업조 생산성 및 영향요인 분석

허영기(Huh, Young-Ki),손창백(Son, Chang-Baek),임진호(Lim, Jin-Ho),안영철(Ahn, Young-Chull),오재훈(Oh, Jae-Hun) 대한건축학회 2014 大韓建築學會論文集 : 構造系 Vol.30 No.12

Few studies on crew productivity has been conducted, although the data is significant for time and cost estimation. Crew productivity data was collected for over 9 months from a nuclear power plant and analysed in order to identify factors driving the productivity. It was revealed that the crew productivity of form work and rebar work was 45.64(㎡/crew·day), 2.93(t/crew·day) on average respectively. The study also found that ‘nightwork’ and ‘total work amount completed’ were identified as drivers for the both works. Moreover, ‘complexity of daywork’ can lead to crew productivity deduction of about 77% for form-work and 81% for rebar-work. The productivity data collected and factors affecting the productivity will help managers to plan and control their similar works. This study will also be beneficial for those performing related studies.

국내 CM 사업의 추이 및 대가 산정 현황 분석

허영기(Huh, Young-Ki),김경욱(Kim, Kyoung-Uk),김대영(Kim, Dae-Young),안혜련(Ahn, Hye-Ryeon) 대한건축학회 2013 大韓建築學會論文集 : 構造系 Vol.29 No.7

According to public announcement meterial from Ministry of Land, the result of CM as increasing for 20% more than last year, it keep to steady growth even Construction Market’s recession. But Regardless of various revisions made, in accordance with its present condition, construction management struggles to deal with unacceptable assessment costs and, therefore, hinders the overall development of the industry. As a result, this research is conducted to analyze fifty counts of illogical calculations ordered by the public CM corporations and examine the existence of irrationality among the expenses.

공원 내 민간투자방식의 소규모 영업시설 설치를 위한 적정운영보장기간 분석

허영기(Huh, Young-Ki),오재훈(Oh, Jea-Ho),임진호(Lim, Jin-Ho),정경순(Jeong, Kyeong-Soon) 대한건축학회 2014 大韓建築學會論文集 : 構造系 Vol.30 No.1

Although many people visit and enjoy the park thanks to the improvement of their living standard nowadays, they experience much inconvenience from insufficient modernized sales facilities. However, public bodies maintaining the parks encounter difficulty to overcome the problem mainly due to shortage of their budget. Three perspective places for sales facilities within two public park in B city were selected in order to demonstrate a simple yet reasonable approach for the bodies to decide an optimal guarantee-operation-period, when they procure the facilities by means of the PPP(Public-Private-Partenership). Number of visitors nearby the places were counted and surveyed in order to forecast annual visitors and sales volume. Then, NPV and Monte-Carlo Simulation was employed to produce probability distribution of the optimal guarantee-operation-period for each facility. The methodology can be a great interest for the public authorities to expand facilities in their park.

CM 전문회사 단장 활용실태 및 개선방안

손창백,허영기,이동은,Son, Chang-Baek,Huh, Young-Ki,Lee, Dong-Eun 한국건설관리학회 2013 한국건설관리학회 논문집 Vol.14 No.2

국내 CM시장이 활성화됨에 따라 경쟁이 심화되어 실제 프로젝트 관리를 담당하는 CM단장의 능력은 CM사업 수주를 위한 중요한 요소가 되었다. 이로 인해 각 CM전문회사는 유능한 CM단장의 확보를 위해 현재 담당 프로젝트가 없더라도 후속 프로젝트의 수주를 위해 CM단장을 일정수 대기상태로 확보하고 있으나, 효율적인 활용방안에 대해서는 체계적인 방법이 마련되지 못한 실정이다. 이에 본 연구는 현재 CM전문회사가 보유하고 있는 대기상태 CM단장들의 활용실태 및 문제점을 분석하고, CM단장의 효율적인 활용을 위한 개선방안을 모색하기 위한 실무적 기초자료를 제시하고자 하였다. 본 연구결과, CM전문회사의 현재 대기상태 CM단장 인력수는 적정 비율 및 인력수에 비해 약 2배 정도 많은 것으로 나타났고, CM단장의 선정기준으로 프로젝트의 수주를 위해 프레젠테이션 능력을 가장 중요한 요소로 고려하고 있었다. 그리고 대기상태 CM단장의 보유 및 활용상 문제점은 크게 고용비용 증가와 현장 및 본사 업무지원능력 부족 및 제한적 활용으로 요약되었고, 대기상태 CM단장의 효율적인 활용을 위한 현장 및 본사 기술지원과 수주능력 강화 및 제도개선 등에 관한 개선방안을 제안하였다. The number of construction management firms has been increased as construction management delivery system has been active in Korean construction market. the capability of leading construction management professional, who is responsible for managing project administration, is important for commissioning construction management contracts. The quality of project proposal and the capability of leading construction management professional, which are assessed by the board of contract awarding committee, are the major contributors for commissioning the public construction management projects administered by the Korean public procurement service for contracting. Therefore, employing a very competent leading construction management professional is the critical strategy for awarding contract to the construction management firms' part. That is why the firms should secure a fixed number of leading construction management professional in a waiting list to proceed the contract commissioning process for expectant candidate projects, even if there is no project assignable to the leading construction management professionals. However, a measure that makes effectively use of the leading construction management professional in a waiting list has not been systematically implemented in the firms. In turn, the firm suffers considerable loss in a project personnel supply and demand plan. Expert opinions were obtained by the survey questionaries administered to top management of the construction management firms which are engaged in the construction management contracts for commissioning the public construction management projects administered by the Korean public procurement service either as principal or co-principal deliverer. This paper presents the findings obtained by investigating the actual employment state of the leading construction management professional in the waiting list and by analyzing the issues involved in mobilizing and demobilizing them. It contributes to implement a practical guide for searching effective solutions to the issues.