PURPOSES : In general, a high-performance concrete construction method is a method of loading mixed cement and other materials on a mobile mixer equipped with a concrete plant. However, the construction cost is high because the unit cost of the mixed cement is very high and the equipment usage fee of the mobile mixer is also high. To compensate for these drawbacks, a cellular spray concrete method was developed. This is a highly functional customized concrete construction method in which admixtures are added to high-flow concrete with cellular (air bubbles) added at the site and constructed through spraying. METHODS : Field workability evaluation using cellular concrete was carried out using a spray method in 2017 and an anti-foaming agent in 2018. The test construction section was set as a new road-pavement construction site. After construction, strength, durability characteristics, and void analysis were performed to compare the construction methods. The results of laboratory tests under optimal conditions were also compared to the on-field results. By comparing the indoor mixing and the on-field results, we analyzed whether there were any problems concerning the performance expression. The economic feasibility at the initial construction stage was analyzed by comparing the existing and the cellular concrete construction methods in terms of material cost and equipment usage fee. RESULTS : In the case of cellular spray concrete, construction through spraying is cumbersome, and the need to additionally use large equipment such as a pump car and compressor constitutes a disadvantage. However, the most relevant feature is that it can be constructed not only on the floor, but also on a slope. In the case of cellular concrete with an antifoaming agent, it was possible to quickly produce high-performance concrete using on-site remixing equipment. By supplying materials to the pouring surface using a conveyor, smooth construction and construction in narrow spaces were also possible. CONCLUSIONS : The cellular concrete method allows the immediate on-site production of high-performance concrete, and it is possible to selectively apply spray construction, antifoaming agent construction, etc.

This study is to evaluate economic effect of the creation project of snow crab, Chionoecetes opilio, spawning and habitat ground in Uljin and Youngdeok county. The main results of this study are summarized as follows: first, 14,400 million won was invested in the creation project cost of Chionoecetes opilio spawning and habitat ground of Uljin and Youngdeok County from 2015 to 2020. Second, the creation project of Chionoecetes opilio spawning and habitat ground directly provides fishing benefits, festival benefits, research and development benefits and employment benefits. Third, on the basis of above benefits, the creation project of Chionoecetes opilio spawning and habitat ground has net present value of 29,900.53 million won, internal rate of return 16.9%, and benefit-cost of 2.91 under a 4.5% social discount rate. Also, the creation project creates 195 jobs. This indicates that the creation project of Chionoecetes opilio spawning and habitat ground not only contributes to the increase in the income of coastal fishery and fishing villages but also to the job making. The result of this study provides useful information to policy makers or project managers as it shows that the project to create spawning and habitat ground should be carried out in consideration of the resource and biological characteristics of individual fish and that economic assessment logic should also be developed based on this. Also, it proves that the project to create a snow crab spawning and habitat ground is a national and local infrastructure project that increases the actual fishing income in the region. At the same time, it maintains the reproducibility function of most fish species, along with enhancing the people's benefits such as fishing village tourism and marine product consumption. Moreover, it provides useful information on budgeting for the continuous development of snow crab spawning and habitat ground in the mid to long-term.

There are two methods for evaluating two or more mutually exclusive projects. One is a total investment approach and the other is an incremental investment approach. The former can rank projects by the criterion of the net present value, but the latter can’t do it. An incremental investment approach is only possible when all pairwise alternatives are compared. Thus an incremental investment approach is superior in ranking them over an incremental investment approach. To do so, a principle of comparison must be established. Comparisons of profitability are reasonable when operating the same amount of investment over the same period of time. One principle is that all projects are invested in the largest of the projects. Another principle is that all projects are invested during the longest project life of the projects. In this paper, even if the principle is followed, it will be shown that the external rate of return fails to rank them. However, the productive rate of return criterion would prove to be able to rank them like the net present value standard, provided that the principle of comparison is kept. In addition, rate of returns can be assessed so that all mutually exclusive projects can be compared at once, such as on the criterion of the net present value. That is, it can be also compared with many other returns, such as the profit rates on financial investments or real investments.

years, aquaculture plays an important role in fishery production in Korea. Nevertheless, aquaculture should be carefully managed by regulations because it also causes environmental load which can threat sustainability of aquaculture. For this reason, Korean government has regulated density of culturing facilities with the Fisheries Law and its adjective decrees. The regulatory compliance of fisheries businesses is very low because the criteria for the regulation of the density were not enacted with scientific research. Thus, this research was aimed to obtain scientific criteria for the regulation of oyster aquaculture in Jaran Bay with economic assessment. For this research, we collected the data necessary for the assessment on five investigation points in the bay for two years. With the data, simulation for the growth rate of oyster was performed and the result showed that at least 25.5% of facilities should be reduced. Also, it was revealed that removing 2 long lines would be most beneficial. The NPV of the best measurement was 35,120,300 won and IRR was 11.7%. With this research, the government will gain more accurate regulatory compliance due to the scientific approach. Moreover, fisheries businesses in oyster aquaculture can obtain flexibility to cope with market fluctuation.

공작물 주차장은 제한된 높이를 갖는 시설물로써, 제한된 층고 내에 합리적 구조가 되도록 계획하는 것이 중요하다. 공작물 주차장은 제한된 층고 내에 주차 통로부(6m)와 주차공간부(5m)를 고려한 11m 전후의 장스팬이 대부분이다. 기존의 합성보는 제한된 층고내에서 충분한 보춤을 확보할 수 없기 때문에, 처짐과 같은 사용성에 대한 문제가 발생한다. 본 연구에서는 박스형 강재보의 상부플랜지를 콘크리트 슬래브의 마감면까지 노출시킨 형상의 합성보를 개발하였다. H형 합성보, U형 합성보, Box형 합성보를 대상으로 2점가력 휨실험을 수행하여, 구조특성을 비교하였다. 그리고 주차장 모듈에 대해 대안설계를 수행하여 경제성과 효율성을 비교평가하였다.

The Ministry of Agriculture, Forestry, Livestock and Food in Korea has done an R&D project to develop new corn and soybean varieties and cultivation technologies with Seoul National University and on-site company for three years in Russia, where Korean government has done the overseas’ agriculture for more than a decade. The objective of this study is to analyze the investment value of three years’ funding. For this, a Cost-Benefit and Scenario analysis approaches were used. The results revealed that 1) For the case of soybean, cost seems to outweigh benefits under a pessimistic scenario, but otherwise in case of neutral and optimistic scenarios. 2) The result of corn shows high economic efficiency for all scenarios. 3) The most important implication of this study is that Korea’s oversea agriculture R&D projects need to expand to different countries, regions, and crops.

For economic evaluation of integrated operation to sewage facilities, benefit-cost analysis was performed to watershed sewage works project in 7 watershed areas, 156 facilities. In this study, the cost before and after integrated operation was compared and benefits are calculated from the reduction of operators, increasement treated pollution loads, reduction cost through operation convenience, reduction water consumption through effluent reuse, and improvement of life benefit. The result showed that cost was 8,500million won and benefit was 16,747million won, so benefit was 49% higher than cost. B/C analysis result showed that B/C ratio was 1.97 and it is similar to other researches. The benefits of integrated operation included convenience of data management, increase of emergency response, decrease of complains with sewage which was not reflected numerically, so the benefits of integrated operation were expected much greater than this result.

이 연구에서는 물량저감 철근상세를 갖는 중공 철근콘크리트 교각 시스템의 전용 설계프로그램과 소성설계 적용 결과를 제시하였다. 개발된 물량저감 철근상세는 경제성과 합리성을 갖으며 공사기간의 단축을 가져올 수 있다. 물량저감 중공 철근콘크리트 교각의 적용을 통해 경제성 평가를 수행하였다. 평가 결과 개발상세가 기존상세에 비해 구조적 합리성, 시공성, 그리고 경제성 등이 우수함을 확인하였다.

The purpose of this study is to evaluate the economic validity of artificial reefs facilities and seeds release programs in Jeju Trial Sea Farm Project for raising fishing people’s revenue. The results of this study show the artificial reefs facilities and seeds release programs have net present value of 15,962.63 million won, internal rate of retrurn 13.86%, and benefit-cost of 1.912 under a 5.5% social discount rate. This suggests that in Jeju trial sea farm project, artificial reefs facilities and seeds release programs increase fisherperson’s revenue.

Virtual metrology(VM) is a promising technology which can convert off-line sampling inspection into on-line total inspection at the manufacturing process. This paper provides an economic evaluation model of VM system which predicts the defects of a target process with Bernoulli sampling inspection. For this purpose, we build M/G/1 queueing models of two systems. One is VM non-applied system and the other is VM applied one. We derive total costs per unit time of each system and conduct sensitivity analysis according to variations of input parameters such as defect rates, various process costs and VM prediction error rates. The proposed analysis model is expected to be used for evaluating economic values of VM system implementation projects.

라오스 정부는 산림의 황폐화를 방지하고 그동안 훼손된 산림 자원의 복원을 위해 외국 자본에 의한 조림사업을 유치하는 노력을 하고 있어, 라오스는 우리나라의 해외 조림목 공급선 확대라는 정책 목표에 부합하는 지역으로 볼 수 있다. 이렇듯 조림 투자 가능성이 점차 확대되어가고 있는 환경 아래, 조림 투자 사업의 경제적 타당성을 미리 가늠해 보는 과정은 투자 의사 결정에 있어 매우 중요한 역할을 차지한다. 본 연구의 기본적인 목적은 라오스 조림 투자 사업에 대한경제적 타당성을 실증적인 차원에서 평가하는 것이다. 모든 투자 사업을 계획할 때에는 B/C ratio나 IRR 등과 같은 타당성지표를 계산하여 사업의 경제성 여부를 판단하게 된다. 그러나 그러한 경제적 타당성 분석 결과의 신뢰성은 분석에 적용되는 편익 항목과 비용 항목이 얼마만큼 현실적인 조건을 충실히 반영하느냐에 의존하게 되며, 투자 사업이 진행됨에 따라 나타나는 여러 불확실성이나 항목의 변동을 감안하는 데에는 큰 제약이 있는 것이 현실이다. 더욱이 사업이 진행됨에따라 사업 기간 중 발생하는 편익과 비용의 변동 사항을 적절히 반영하여 경제성을 재평가한다면, 나머지 사업 기간 중의 투자 계획 수정 과정이나 동종 업계의 투자 의사 결정, 나아가 정부의 관련 정책 의사 결정 과정에 기여하는 바가 크다고 할 수 있다. 이상과 같은 목적에 부합하는 연구를 수행하기 위하여, 본 연구에서는 현재 해외에 진출하여 조림사업을 추진하고 있는 기업 중, 라오스에 진출한 M산업을 분석 대상으로 선정하였다. M산업은 조림 면적이나 사업비 규모 측면에서 상대적으로 소규모의 투자 업체로 간주되는데, 2002년부터 3여 년 동안의 사업 준비기간을 거쳐 2005년 라오스에 진출한 소규모국내 업체이다. 현지 조사를 바탕으로 가정한 비용 항목과 편익 항목의 각 수치를 최대한 보수적인 관점에서 적용하여 경제성을 분석한결과, IRR은 19.62로 나타나 최근에 자본의 기회비용으로 간주될 수 있는 시중 이자율을 크게 상회하는 것으로 나타났다.한편 8%의 할인율에서 B/C ratio는 1.54로 나타나 1원의 투자에 대응하여 0.54원의 순수익을 기대할 수 있는 것으로 분석되었다. 또한 이 때 미래 순수익 흐름의 합계인 NPV는$4,529,182로 나타났다. 분석에 적용된 할인율이 각각 5%부터20%까지 상승함을 가정할 때, B/C는 1.70으로부터 0.99까지하락하는 것으로 나타났으며 동시에 NPV는 $6,773,935로부터 -$39,155까지 하락할 수 있음이 분석되었다. 민감도 분석 결과 편익의 크기가 20% 가량 증가할 때, IRR은 24.69%까지 상승하는 것으로 나타났다. 반대로 편익의 크기가 20% 가량 감소할 때, IRR은 13.53%까지 하락하는 것으로 나타났다. 비용 항목 변동의 경우 주요 비용 항목의 크기가 각각 10% 및 20% 씩 감소할 때, IRR은 각각 18.86% 및 18.13%로 하락하는 것으로 나타났다. 결론적으로 현재의 국내 자본의 기회비용 수준을 8% 정도로 감안했을 때 모든 시나리오의 분석 결과가 이를 크게 상회함으로써 민감도 분석 결과 또한 다양한 가격 조건 하에서도 본 사업의 경제성은 충분히 확보된 것으로 판단할 수 있다.

현재 국내에서 생산되는 구조용 강재의 강도는 크게 5가지로 구분할 수 있다. 경제적인 구조설계를 하기 위하여 적절한 강도의 선정이 우선적으로 요구되는데 현재는 이와 관련된 기존 자료가 충분치 않은 상태이다. 최근, 국내에서 항복강도가 650MPa인 고강도 강재가 개발되어 구조용 강재의 강도 범위가 더 커졌기 때문에 부재 종류별 강재의 선택에 따른 경제성의 차이도 더 커졌을 것으로 예상된다. 본 논문에서는 경제적인 구조설계에 도움이 되도록, 항복강도 235MPa, 325MPa 및 650MPa 강재를 다양한 구조부재에 적용함으로서, 고강도 강재 적용에 따른 부재 종류별 경제성을 분석하였다.

몽골은 석탄 매장량이 매우 풍부하고 석유연료를 전적으로 수입에 의존하기 때문에, 석탄액화플랜트 건설에 필요한 충분한 여건을 갖추고 있다. 본 연구에서는 몽골에 하루 10,000배럴의 석유연료를 생산할 수 있는 석탄액화플랜트를 건설할 경우에 대한 경제성분석을 수행한다. 먼저 기존에 있는 산업계의 석탄액화플랜트 프로젝트 데이터와 학계의 연구결과를 토대로 몽골 석탄액화플랜트 건설에 필요한 비용과 기대수명, 그리고 예상 수명기간 동안 운영했을 때 발생하는 운영