PURPOSES : The evaluation of the low-temperature performance of an asphalt mixture is crucial for mitigating transverse thermal cracking and preventing traffic accidents on expressways. Engineers in pavement agencies must identify and verify the pavement sections that require urgent management. In early 2000, the research division of the Korea Expressway Corporation developed a three-dimensional (3D) pavement condition monitoring profiler vehicle (3DPM) and an advanced infographic (AIG) highway pavement management system computer program. Owing to these efforts, the management of the entire expressway network has become more precise, effective, and efficient. However, current 3DPM and AIG technologies focus only on the pavement surface and not on the entire pavement layer. Over the years, along with monitoring, further strengthening and verification of the feasibility of current 3DPM and AIG technologies by performing extensive mechanical tests and data analyses have been recommended. METHODS : First, the pavement section that required urgent care was selected using the 3DPM and AIG approaches. Second, asphalt mixture cores were acquired from the specified section, and a low-temperature fracture test, semi- circular bending (SCB) test, was performed. The mechanical parameters, energy-release rate, and fracture toughness were computed and compared. RESULTS : As expected, the asphalt mixture cores acquired from the specified pavement section ( poor condition – bad section) exhibited negative fracture performances compared to the control section (good section). CONCLUSIONS : The current 3DPM and AIG approaches in KEC can successfully evaluate and analyze selected pavement conditions. However, more extensive experimental studies and mathematical analyses are required to further strengthen and upgrade current pavement analysis approaches.

Heavy bitumen scattered in the underground sedimentary layer is a kind of unconventional energy source, and by extracting it, a production well is excavated in the sedimentary layer and high-temperature and high-pressure steam is injected to reduce the viscosity of bitumen and recover it to the ground steam assisted method is applied. As a recovery method that uses the steam effect of the dilution effect of solvent injection, it is a recovery method that can increase thermal efficiency. In this study, the process system of the central processing facility(CPF) of the hybrid steam-solvent recovery method that injects solvent into the existing steam assisted method was analyzed, and the core facilities for each process were identified, and hybrid steam-solvent recovery compared to the existing steam assisted method. In the case of the method, it was evaluated that the amount of steam supply and all utility costs decreased according to the solvent injection.

최근 도시 과밀화와 건축물 고층화로 인해 빌딩풍에 의한 시설 피해는 물론 보행자의 안전을 위협하는 풍환경에 대한 우려 가 커지고 있다. 빌딩풍 피해 저감을 위한 방안으로 건축물 주변 풍환경 평가를 통해 도시의 풍환경을 개선하는 것이 중요하다. 이를 위해 풍동실험을 대체하거나 보완하는 수단으로 최근 전산 유체역학 기법 (CFD)의 적용이 받아들여지고 있으며, 국토교통부가 보행 자 풍환경 평가를 위한 CFD 활용 가이드라인을 제시한 바 있다. 본 논문에서는 이 가이드라인의 적정성을 평가하기 위한 전산해석을 수행하였다. CFD 결과의 검증을 위해 일본 건축학회가 제시한 모형과 풍동실험 결과를 사용하였다. 평가결과 일부 위치에서 풍동 실 험값과 CFD 결과의 풍속 차이는 있으나 격자의 상세도가 정확도에 미치는 영향과 CFD를 이용한 보행자 풍환경 평가 가능성을 확인 하였다. 또한, 건물 주위의 상승풍, 하강풍 및 와류 등으로 인한 돌풍이 잘 모사되고 있음을 확인하였다.

This study deals with replacement analysis of deteriorated equipment for improving productivity of production system. Frequent breakdown of the deteriorated equipment causes a situation that reduces productivity such as low product quality, process delay, and repair cost. However, the replacement of new equipment will be required a high initial investment cost, so it is important to analysis the economic feasibility. Therefore, we analyze the effect of the production system due to the aging effect of the equipment and the feasibility of equipment replacement based on the economic analysis. The process flow, working time, logistics movement, etc. are analyzed in order to build the simulation modeling for a ship and land switchboard production system. Using numerical examples, the economic feasibility analysis of equipment replacement through replacement of existing deteriorated equipment and additional arrangement of new facilities is performed.

This study aimed to analyze the economic feasibility of the reduction of working safety accidents in stow net fishery through the prevention education to fishing crews. The benefit was evaluated by estimating insurance payment amount that was reduced through prevention education. The decreasing rate of working safety accidents was presumed to follow the experience in Japan. The cost was assumed as the cost of textbook development. Results indicated that IRR was estimated to be 79.9% in case of scenario assuming no additional operating costs while IRR was 56.3% in case of scenario assuming 10% additional operating costs. In addition, the economic feasibility would be secured when annual operating costs increased to 274 million won according to the result of sensitivity analysis.

Aimed at determining whether China’s active carbon emission reduction policy can respond to the threat of carbon tariff of the USA, this study proposed two kinds of carbon tax schemes for the USA and China, same carbon tax policy and a differential carbon tax policy. Four scenarios are set: the USA only charging carbon tax on domestic products; the USA charging carbon tax on domestic products and carbon tariff on imported products from China; the USA and China taking the same carbon tax policy on domestic products; the USA and China taking the differential carbon tax policy on their domestic products. Global Trade Analysis Project Energy model is applied to discuss whether China’s active measure to reduce carbon emissions can be an effective solution to the threat of carbon tariff of the USA. The research results show that China’s active measure of the same carbon tax policy as the USA is not effective to cope with carbon tariff of the USA. However, it is an effective measure to take a differential carbon tax policy. The specific policy implications of the study are discussed in conclusion.

PURPOSES: This study analyzes feasibility for application white pavement markings in the roadways with median barrier. METHODS : By reviewing numerous relevant laws, standards, and operational cases, the white pavement markings' excellence was demonstrated. Driver’s behavior was analyzed through a virtual driving experiment using driving simulator and field tests. RESULTS: First, white pavement markings are superior to yellow pavement markings in terms of visibility, economics, and safety. Second, as a result of virtual driving experiment, the color of line in the roadway with median barrier didn’t affect the driver’s behavior such as the average vehicle speed, the distance bias in the lane and the separation distance from the centerline. Third, field test demonstrated that the driver tended to recognize the median barrier as an obstacle. In addition, the central driving ratio in the lane was increased due to improving the visibility of line at night in case of the white pavement markings. CONCLUSIONS : The application of white pavement markings in the roadways with median barrier can enhance traffic safety by improving the visibility of line at night.

This study aimed to analyze the profitability and economic feasibility of hairtail trolling line gear that was developed for the last 3 years (2015-2017). The new fishing gear technology development was accomplished to solve the current problem of fishermen shortage in hairtail targeting fisheries in Jeju region. Results indicated that the profitability of developed hairtail trolling line fishery was estimated to be 36.1 % which would be higher than that of other hairtail targeting fisheries in Jeju region. In addition, as an economic feasibility, the net present value and the internal rate of return of a 20-year cash inflow and outflow were evaluated to be 400.2 million won and 66.9 %, respectively. However, sensitivity analyses of main variables showed that the profitability and economic feasibility would be vulnerable to catch amount and market condition changes.

Ohmic heating is one of advanced thermal processing techniques which utilize conversion of electrical energy into heat. In our study, a feasibility of ohmic heating was tested to cook instant rice cake to improve energy efficacy as an alternative heating methods of conventional electrical kettle. Ohmic heating was conducted using customized ohmic cell (7.5×4.5×9.5 cm) equipped with titanium electrodes. Instant rice cakes in soup were ohmically heated up to 100°C at different electric fields (9, 12, 15 & 18 V/cm) and temperature holding times (60, 80, 100 & 120 s). Thermocouple was placed into both soup and rice cake to evaluate the temperature profile and energy efficacy. Temperature, voltage and current across the sample were measured and recorded at every 3 s using data acquisition system (DAQ). Mathematical model was developed to calculate the internal energy generation rate (QR, W). Internal energy generation rate (QR, W) was integrated versus temperature come-up time (s) to compute the total internal energy dose (ET, J) using MATLBA software. For energy efficacy (Eff), it was calculated ratio of total internal energy dose (ET, J) to heat quantity (Qh, J). During ohmic heating, temperature come-up time was significantly reduced as a function of elevated electric field (P<0.05). For example, 9V/cm of electric field showed 6.2±0.4 min of temperature come-up time up to 100°C. Higher electric field at 18 V/cm reduced temperature come-up time to 1.9±0.1 min. The electric field of 15 V/cm showed the best energy efficacy as 0.78 which meant 78% of electrical energy was converted into thermal energy for heating. In the texture profile analysis, the most preferable harness was found as 6.191 N at 15 V/cm and 100 s holding time. Our study showed the potential of ohmic heating to cook instant rice cakes for home meal replacement (HMR) and outdoor foods.

정부에서는 발주하고 관리하는 정보화 사업은 년 3조원 규모로, 이러한 정보화 사업은 대부분 사업수행 업체가 제출한 제안서를 분야별 전문가들에 의해 평가를 진행한 후 사업 수행자를 선정하게 된다. 제안서 평가는 제시된 평가기준에 의해 평가위원의 정성적 판단에 따라 점수를 부여 하고 있으나, 실제 평가위원이 어떠한 부분에 중점적으로 관심을 가지고 점수를 부여하는지는 알 수 없다. 이에 본 연구에서는 평가위원의 제안서 평가 시 어떠한 요인이 평가점수 부여에 영향을 미치는지 분석 하고자 한다. 연구를 진행하기 위해서는 평가를 진행하는 평가위원을 직접 대면 조사를 통해 자료를 수집해야 한다. 그러나 평가위원 명단이 보안상 공개되지 않아서 조사에 현실적으로 어려움이 있고, 또한 설문조사 등으로 직접 조사하기에는 부적절한 측면이 있다. 본 연구에서는 온라인 평가시스템에 등록된 평가위원의 평가의견(Text) 분석을 통해 요인을 분석 하고자 한다. 데이터 분석 도구인 R을 이용하여 온라인 평가시스템에 등록된 평가의견에서 형태소를 추출, 평가에 영향을 줄 수 있는 주요 요인과 극성을 나타내는 Keyword 사전을 구축 하였고 주요 요인을 이해력, 수행력, 관리력 3개의 차원으로 분류 하였다. 이를 통해 평가위원이 실제 입력한 점수와 주요 요인, 극성 조합에 의해 산출된 점수가 어떠한 상관 관계가 있는지 분석하기 위하여 회귀 분석을 실시, 주요 요인들이 평가 점수에 미치는 영향도에 대한 신뢰도를 검증할 계획이다. 본 연구의 결과는 비정형 형태로 입력된 의견을 실제 평가결과 점수로 수치화 할 수 있는 방법론 수립의 기초가 될 것으로 기대 한다.

본 연구는 파라과이에 대한 조림투자의 경제적 타당성을 분석하기 위하여 수행되었다. 한국은 목재자 급률이 낮아 90년대 초반부터 적극적인 해외조림투자에 나서고 있으나, 그 투자의 대부분이 동남아시아 에 집중되어 있다. 이러한 상황에서 조림목 생장이 우수하고 적극적인 조림 지원 정책을 추진하고 있는 파라과이는 한국의 해외조림투자 대상지로서 훌륭한 대안이 될 수 있다. 하지만 지구 반대편이라는 지 정학적 위치에 대한 거리감으로 인하여 한국기업은 파라과이 해외조림투자에 대하여 적극적으로 검토하 지 않고 있다. 파라과이 조림투자에 대한 정보가 부족한 것도 기업의 접근을 막는 하나의 요인이며, 우 선적으로 조림사업의 수익성에 대한 자료가 요구된다. 본 연구에서는 파라과이 해외조림투자를 파라과 이 내수 시장에서의 원목 판매와 현지 위탁가공 후 한국시장으로의 제재목 수출, 두 가지 경우에 대하 여 경제적 타당성을 분석하였다. 그 결과, 두 시나리오 모두 높은 경제적 타당성을 가지고 있는 것으로 분석되었다. 원목의 내수시장 판매의 경우, IRR 9.64%, NPV U$ 2,811,888로 나타났다. 제재목 한국 수출의 경우, IRR은 17.51%로 현지원목판매 대비 7.87%p 상승하였고, NPV는 U$ 38,260,086로 현지 원목판매 대비 U$ 35,448,198 상승하였다. 본 연구는 원거리라는 점으로 인해 외면 받아온 남미, 특히 파라과이 조림 진출에 대한 가능성을 새롭게 분석한 것에 큰 의의가 있다하겠다.

This paper aims to analyze the economic feasibility and investigate the possibility of elastic seismic design of wind-designed highrise concentrically braced frames considering change of mechanical properties of Korean steel under the strong wind and the low seismicity in Korea. To this end, first, highrise concentrically braced frames were designed considering strong wind load. And then, analyses of the economics of them were performed. The seismic performance evaluation of wind-designed highrise buildings was conducted using the response spectrum analysis procedure. Analysis results show that it is possible to save up to approximately 90% of the amount of steel on the 10% increase in steel strength without serviceability. However, with serviceability, the design sectional area of the steel with relatively high strength tends to increment considerably because of the lateral stiffness due to reduction of the inertia moment and so on. This point might apply to limitation of the steel with high tensile yield strength.

This study concerned the analysis on the efficiency of the conversion of water tank type supply system to direct water supply system to examine the feasibility of the conversion, as well as the calculation of optimal conversion range that enables the supply of safe, high-quality water at stable pressure in accordance with the standards of water supply facility. The results of this research showed that when converting water supply system from water tank type supply system to direct water supply system, more nodal points could be properly converted and more reduction of electricity usage was expected in case water pressure rather than residence time was fixed. This means that higher efficacy can be obtained by fixing water pressure when converting water supply system. However, since the number of the locations that received on-spot inspection was small and the electricity usage measured was not exclusively by water supply facility, it is difficult to judge that such reduction of electricity usage accurately represents reduced electricity usage by water supply facility alone. therefore, after having secured on-spot information about a larger number of locations in apartment complexes that have converted water supply system, and utilizing information about electricity usage exclusively by water supply facility, the proposed method of this research could be applied to accurately deducing expected reduction of electricity usage by water supply facilities of various other apartment complexes. It is also considered possible to deduce an effective operation method of water supply system by finding out an area that shows low pressure or low residual chlorine concentration in the optimal conversion range of water supply, followed by estimating the proper location of pumping station or the proper chlorine dosage at the power purification plant that supply water to the target area.

PURPOSES : The applicability of the mechanics-based similarity concept (suggested by Feng et al.) for determining scaled variables, including length and load, via laboratory-scale tests and discrete element analysis, was evaluated. METHODS: Several studies on the similarity concept were reviewed. The exact scaling approach, a similarity concept described by Feng, was applied in order to determine an analytical solution of a free-falling ball. This solution can be considered one of the simplest conditions for discrete element analysis. RESULTS : The results revealed that 1) the exact scaling approach can be used to determine the scale of variables in laboratory tests and numerical analysis, 2) applying only a scale factor, via the exact scaling approach, is inadequate for the error-free replacement of small particles by large ones during discrete element analysis, 3) the level of continuity of flowable materials such as SCC and cement mortar seems to be an important criterion for evaluating the applicability of the similarity concept, and 4) additional conditions, such as the kinetics of particle, contact model, and geometry, must be taken into consideration to achieve the maximum radius of replacement particles during discrete element analysis. CONCLUSIONS : The concept of similarity is a convenient tool to evaluate the correspondence of scaled laboratory test or numerical analysis to physical condition. However, to achieve excellent correspondence, additional factors, such as the kinetics of particles, contact model, and geometry, must be taken into consideration.

PURPOSES : This study evaluated the feasibility of implementing protected-permissive left-turn (PPLT) signals at three-leg signalized intersections. METHODS: A three-leg signalized intersection with permissive left-turn was first selected. A VISSIM simulation model was constructed using data collected from the test site. The VISSIM network was calibrated by adjusting related parameter values in order to minimize the difference between the simulated and surveyed critical gap. The calibrated network was validated by the number of waiting left-turning vehicles per cycle. Finally, the mobility and safety measures were extracted from simulation runs in which permissive, protected left turns as well as PPLTs were realized based on diverse traffic volume scenarios. RESULTS : The mobility-related measures of effectiveness (MOEs) of the case with PPLT outperformed the other two left-turn treatment scenarios. In particular, the average waiting time per cycle for the left-turn vehicles in the case with PPLT was reduced by 30 s. The safetyrelated MOEs of the case with PPLT were somewhat higher than those in the case with protected left-turns and much higher than those in the case with permissive left-turns. CONCLUSIONS : Based on the mobility- and safety-related MOEs generated from the VISSIM simulation runs, the use of PPLT seems to be feasible at three-leg signalized intersections where the left-turn is permissive and a pedestrian signal exists at the conflicting approach. However, in order to use the PPLT in earnest, it is necessary to revise the road traffic act, traffic signs, and related manuals.