• Environmental and Resource Economics Review
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• v.29 no.2
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• pp.247-270
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• 2020

The value of a statistical life (VSL) plays a very important role in estimating the benefits of environmental policy. It is used, for example, as a unit of monetization of health benefits resulting from the reduction of air pollutants, which is the basis of cost-benefit analysis of policies. The VSL can be defined as the value that people of each society are willing to pay to reduce the risk of death, so the value should reflect the characteristics of its members. In this study, we apply a choice experiment with 3,081 respondents collected through a web survey were divided into two samples according to the type of questions. Among the various estimates, the most appropriate estimate of the VSL is about 1.3 billion won from 1,528 sample, which is similar to the results of the meta-analysis using estimates from prior studies conducted in Korea. In addition, this study shows that a private prevention program is preferred to reduce the risk of death from cancer rather than a public program.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.713-722
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• 2000

This study analysed error of measurement and reproducibility for particle size analysis by the laser diffraction spectrometer. Laser diffraction spectrometers has become a very important method of particle size analysis. This measuring method has the advantage of simple operation, good reproducibility and rapid analysis. A feeding and dispersing system have been developed, which allows mass throughputs between 0.1~23 g/min in flowing air and 1.4~35% in flowing liquid. It has been used as a feeder unit for wet and dry particle size analysis from diffraction patterns. Relevant parameters, such as particle shape, particle size, dispersion, flow rate, concentration were analysed for measuring error. And system parameters of instruments for measurement of dynamic processes, eg, measuring time, focal plane, injection pressure drop and dispersion effect by the ultrasonic and mixing of preliminary treatment, were also discussed.

• Journal of Integrative Natural Science
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• v.13 no.1
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• pp.27-33
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• 2020

The unsustainable human activities like increased use of automobiles, heavy industrialization and the use of large volumes of fertilizers, chemicals and pesticides in the agricultural land cause climate change problems in one way or another. Under normal circumstances, the heat radiations from the sun will be reflected back. An excessive volume of GHGs in the atmosphere would prevent these radiations from reflecting back. East Asia is facing severe climate change issues in recent times. A lot of climate change problems such as hurricanes and floods have been reported from this region in the last couple of decades. The study aimed at investigating the climate change in East Asia with changing Sea Surface Temperature (SST). The study adopted a quantitative research method with a case study research design where a deliberate focus was made on the East Asia Region. Secondary data was gathered and analyzed to yield both descriptive and inferential statistics. The study concluded that the impact of East Asia Climate variability was significant mainly for some extreme events. Also, the study concluded that there was a significant link between the change of the East Asia climate variability and that of the sea surface temperature. Further, the study concluded that a linear relationship existed between the sea surface temperature and the climate of East Asia. Hence, a linear regression was a significant predictor of the East Asia Climate (EAC) based on changing sea surface temperature. The model revealed that 37.4% of the variations in the climate change index were explained by the changes in the sea surface temperature. The climate was expected to change with a value of 49.48 for a unit change in the sea surface temperature.

• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.299-306
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• 2002

The purpose of this research was to develop a rapid setting cement latex modified concrete (RSLMC) for bridge deck repairing and overlaying. The main experimental variables were latex contents, antifoamer contents and water-cement ratioes. The workability, strength development and permeability were measured as responses. The results showed that latex content increased the slump and reduced the unit water required for same workability. The air contents were measured as 8.0∼9.0％ and 2.0∼3.0％ without antifoamer and with 1.6∼3.2％ of antifoamer, respectively. This resulted in the increment of compressive strength development by 10∼20 ％. The flexural strength of RSLMC increased greatly as the latex content increased, but not in compressive strength. The compressive strength and flexural strength developed enough for opening the overlayed RSLMC to the traffic after 3 hours of RSLMC placement. The permeability of RSLMC was evaluated as negligible due to its very low charge passed. Thus, RSLMC could be used at repairing or overlaying the concrete bridge deck at fast-track job sites.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.661-664
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• 2008

As architectures have recently become high-risers and megastructured, stable high strength products have been ensured. Accordingly, use of precast concrete accouplement has been increased in order to facilitate air compression and rationalize construction. Since not only external heating but also internal temperature rise caused by the accumulation of cement hydration heat in manufacturing process, precast concrete members with large cross-section used for high-rise mega-structure's columns and beams may exhibit different temperature history compared to the precast concrete members for wall and sub-floor with relatively small cross-sections. Therefore, this study aims to elucidate the characteristics of temperature history of mass concrete members cast with high-strength concrete for precast concrete application. In this study, large cross-sectional precast concrete mock-up, unit cement quantity, and temperature histories in manufacturing precast concrete member under different curing condition were inclusively investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.405-408
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• 2008

The most effective factors that improve sections and elongate spans of the prestressed concrete girders are shapes of sections and strengths of concretes, and the concrete strength is more influenced to enhance the allowable tensile strength on top and bottom fibers than increasing of flexural strength of girders. In this study, 60 MPa high-strength prestressed concretes were constructed at the Wonsoo Bridge where in the 1st section of expanding constructions of the Nonsan to Junjoo Expressway, the high-strength concrete was placed on the eight- 35 meters simple span IPC girders of four lanes of Nonsan direction. During casting of girder concretes, quality controls were carried out with continuing controls of surface moistures and corrections of the unit water using the air-meter methods right after batching. It was confirmed that compressive strengths of girder concretes ensure the target strength and the heat of hydrations of girder concrete were measured. Though using same materials and constructing methods, there're a wide range of strengths of each girder, so, when high-strength concretes cast in the place hereafter, a countermove should be prepared.

• Journal of Environmental Health Sciences
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• v.40 no.5
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• pp.425-434
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• 2014

Objectives: The purpose of this study is to introduce the establishment process and results of the Seoul Metropolitan Government's road map on environmental health policy. Methods: The process consisted of expert group meetings, civic participation, research, and questionnaire survey for priority environmental health policy agenda items in Seoul. Results: The announced vision for the environmental health policy was "a healthy environment, safety in Seoul". This policy was established in order to define environment health policy initiatives for a period of five years with an aim to protect Seoul citizens' health from hazardous environmental factors. The resulting Seoul environmental health policy consisted of four areas and 16 key agenda items. The four areas were "Protection for children against hazardous materials", "Enhancement of health and safety of all", "Carcinogen-free and endocrine-disrupting chemical-free Seoul (reducing environmental exposure to hazardous materials), and "Establish the foundation of environmental health policy". Sixteen key agenda items include the enhancement of management of spaces for children, certification of environmental health status at schools, establishment of a unit responsible for the environmental health of children, strengthening environmental health management for susceptible populations (children, the aged, and the socioeconomically vulnerable), management of hazardous materials, physical hazardous factors (noise, radiation, etc.), indoor air quality, and the enhancement of monitoring, research, and regulation of environment health. Conclusion: The Seoul Metropolitan Government established an environmental health policy road map for a five-year period (2013-2017). To implement this environmental health policy, budget allocation, and detailed execution plans are required.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.459-465
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• 2007

This study was conducted to calculate the LCC of a apartment complex with a type of heating system, district heating and cogeneration system. For the purpose of analyzing LCC according to size of apartment complex, 500, 1,500 and 4,000 houses of model apartment selected. This research performs design of heating system and the life cycle cost analysis including an initial cost, energy cost, maintenance and operation cost, replacement cost and renovation cost during the project period(15years). According to the calculated results, 1) Initial cost of cogeneration system with 500, 1500 and 4000 houses is higher than district heating system each of 20%, 13%, 12%. 2) In case of cogeneration system, the payback period by electric generation is 5.21, 4.92 and 4.47 years and saving cost was calculated 29 billion won, 94 billion won and 262 billion won after payback period. 3) Cogeneration system LCC was 1.12, 1.07 and 1.06 times larger than district system with the size of apartment complex. According to the case of this study district heating system is more efficient than cogeneration system in terms of the reduction of LCC. 4) Gas Engine Co-generation System is more efficient than other systems because it can collect progressive part from electric charge progressive stage system. However, the efficiency is decreasing because of raising of fuel bills(LNG) and lowering of power rate for house use. Especially the engine is foreign-made so the cost of maintenance and repair is high and the technical expert is short. 5) District heating is also affected by fuel bills so we should improve energy efficiency through recovering of waste heat(incineration heat, etc.). Also, we should supply district cooling on the pattern of heat using of let the temperature high in winter and low in summer.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.108-116
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• 2015

A missile defense system is composed of radars detecting incoming missiles aiming at defense assets, command control units making the decisions on weapon target assignment, and artillery batteries firing of defensive weapons to the incoming missiles. Although, the technology behind the development of radars and weapons is very important, effective assignment of the weapons against missile threats is much more crucial. When incoming missile targets toward valuable assets in the defense area are detected, the asset-based weapon target assignment model addresses the issue of weapon assignment to these missiles so as to maximize the total value of surviving assets threatened by them. In this paper, we present a model for an asset-based weapon assignment problem with shoot-look-shoot engagement policy and fixed set-up time between each anti-missile launch from each defense unit. Then, we show detailed linear approximation process for nonlinear portions of the model and propose final linear approximation model. After that, the proposed model is applied to several ballistic missile defense scenarios. In each defense scenario, the number of incoming missiles, the speed and the position of each missile, the number of defense artillery battery, the number of anti-missile in each artillery battery, single shot kill probability of each weapon to each target, value of assets, the air defense coverage are given. After running lpSolveAPI package of R language with the given data in each scenario in a personal computer, we summarize its weapon target assignment results specified with launch order time for each artillery battery. We also show computer processing time to get the result for each scenario.

• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.501-506
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• 2011

The study and techniques of system engineering have been applied to various fields including space-air, national defense division in advanced countries. Korea is currently in the early stages of introducing system engineering scheme in railway system and national defense division restrictedly. As theory and application of system engineering covers a wide scope, documents management and requirement analysis technology applied to establishment of standard and core unit development of the research target. The techniques which are historical management and trace among standards for establishment of standard are introduced using SE tools and participating agencies shared the information by constructing of database from all documents which are generated from the project. Through the functional analysis of the requirements for the intelligent station monitoring system in basic design stage, established requirements are verified and will be made official announcement as standard of the intelligent station monitoring system.