• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.169-173
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• 2015

This study is to predict the life exponent by measuring, over 7 years, the insulation resistance of high-voltage cables in 22 kV operation for 13 years. We found out the lifetime index in order to determine the time-dependent trend of deteriorating performance of power cables. The insulation resistances decreased according to elapsed time. We found that: the initial measurements of the cable systems were in agreement with the deterioration properties of the Arrhenius Law. By analyzing the life curve of the cable system, we also verified that the value of the life exponent (n) in the v-t characteristics defined by Weibull distribution has values from 10 to 11. When designing the cable system, the initial value of life exponent was chosen as 9 without any grounding. We have verified that the theoretical grounding based on the design safety of n=9 was actually the best one available. In the short term, we apply our research result to the diagnosis and evaluation of the power cables. In the long run, however, we plan to reduce the cost of the installation and management of cable systems in operation at power stations.

• Journal of agricultural medicine and community health
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• v.19 no.1
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• pp.31-39
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• 1994

We carried out this study by analyzing the annual reports, surveyed by medical college student(Ewha Woman's University) through the medical records of new patients of Su-Dong Myon Health Subcenter from 1982 to 1992, and the specific survey data of 247 in Su-Dong Myon area which consists of 5,454 population and 1,651 household(43.6% farm household), in December, 1993. Results were as follows: 1) The number of population in Su-Dong Myon is 5,265 in 1982, 4,905 in 1984, 4,885 in 1986, 4,820 in 1988, 4,663 in 1990, 5,454 in 1992. 2) Since 1982, the annual utilization rate of a rural health subcenter showed decreasing tendency: such as 609(the highest rate) per 1,000 inhabitants in 1982, 485 in 1984, 525 in 1985, 281 in 1988, 316 in 1990 and 197 in 1992. The utilization rate by sex was decreasing chronologically in male, and age-specific utilization rate showed rapidly decreasing tendency since 1982 : 1,037 per 1,000 inhabitants in 1982, 877 in 1984, 1,084 in 1986, 519 in 1988, 538 in 1990 and 333 in 1992, in age group of 0-14, but not changing tendency in age-groups of 65 and over. 3) The monthly utilization rate of a rural health subcenter showed increasing tendency in March, July and August from 1982 to 1987, and in March and May from 1988 to 1992. 4) The patient rate of medical insurance showed increasing tendency since 1983: 17.0% per 100 patients(the lowest rate) in 1983, 21.3% in 1985, 20.4% in 1987, 70,0% in 1989 and 77.8% in 1991. However, the patient rate of Medicaid showed no specific change. 5) The utilization rate by the remedial measures for primary health care showed 30.8% of the answered in private special clinic, the highest rate, and 30.0% in drug stores, 25.5% in health subcenter, 10.5% in hospital and 1.2% in oriental clinic. In favorite physicians for primary health care, specialist was the highest rate, 48.6% of the answered, and general practitioner, 39.7% and home doctor, 8.9% in next order. And 70.8% of the answered experienced to visit the health subcenter more than once. 6) Disfavorite reasons of health subcenter were insufficient equipment(42.1%, the highest), and the next order, short cure time per day(25.1%), "be not cured"(12.2%), "be not(6.9%) and unkindness(3.6%), And the major obstacles in utilizing the medical facilities for primary health care were farm works(41.7%, the highest), distance(27.1%) and medical cost(11.4%).

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.2
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• pp.29-37
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• 2012

An experiment for an optimized automatic greenhouse environment in a flower farming greenhouse by building a ubiquitous sensor network with various sensors was conducted and the results were evaluated. And various culturing environmental information and data in the greenhouse were collected and analyzed. Then, the greenhouse was designed to maintain the best culturing environment on the basis of existing recommended optimized figures. By measuring the growth of the crops in the greenhouse, A system which controls facilities in the greenhouse to maintain the best culturing environment in accordance with change in the environment was analyzed.Computer simulation result proced that we discovered that controlling the facilities and the artificial light source increased production, enhanced quality, reduced labor and heating cost immensely. The experiment has proved that the u-flower farming system can maximize the income of farm families by sending warning messages to users of this system when weather suddenly changes so that users may cope with such changes and maintain the best culturing environment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.4
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• pp.729-738
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• 2017

With the signing of the Paris Agreement, which is the new climate change agreement at the end of 2015, it will have a great impact on Korea environmental policy. The construction industry, which accounts for 42% of Korea's total $CO_2$ emissions, has been implementing various policies to improve the environmental problems. However, it is only applying passively to other projects except eco-friendly building certification. This is because most of the eco-related systems are based on building facilities. Therefore, there is a need for a new eco - friendly design evaluation model that can be widely applied not only to architecture but also to civil engineering facilities. In this study, a new model is developed based on the existing VE model, which adds new factors to evaluate the environmental friendliness, potential environmental pollution concept and environmental risk of facilities. This model is an eco-friendly design evaluation model that enables decision makers to effectively select alternative environmental criteria at the design stage. As a result of the case analysis of the block retaining wall and the alternative retaining wall, the value of the eco - friendly value of the alternative was 1.026 times higher than the original one. If this model is used at the design stage, it is expected to contribute not only to the construction of environmentally friendly facilities but also to the reduction of carbon emissions.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.265-272
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• 2011

Even though concrete is the most important material for building structures, its intrinsic gray color degrades urban esthetics. In order to improve this problem, coloring methods of mixing pigment in concrete batch and painting the surface of concrete surface have been tried. However, applications of the coloring methods in construction field are difficult due to high cost and low durability. Recently, acid stain agent is emerging as a new coloring method for concrete. It is able to apply a remarkably thin colored layer on a concrete surface from chemical reaction between acid and alkaline solutions. This study has examined the changes and variations of the surface layer of mortar specimen from chemical reaction of acid stained agents. The colors were changed into natural irregular stains according to aging. After the staining, no shape change was found from visible inspections. Microstructure of the colored surface applied with acid stained agent was much rougher than that of original mortar. When the colored layer was compared to original surface, crystals of hydrate such as $Ca(OH)_2$ and C-S-H gel were observed. Surface hardness was same or slightly higher in the colored layer. The value of pH was reduced by approximately 10%, weight contents of elements such as Ca, Si, and Al were low. In the chemical composition of the colored layer, the non-cement based elements of Mn, Cr, and Cu increased. Also, Fe and alkali elements of K and Na increased.

• Journal of Environmental Policy
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• v.8 no.4
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• pp.95-124
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• 2009

This study aims to introduce greenhouse gas emission trading in Korea as a highly cost-effective mechanism for controlling emissions. The Basic Act on Low-Carbon Green Growth will cover methods of emissions allocation, national inventory, and trading systems (i.e. emissions trading platforms, national registry,and clearing and settlement platforms). The Korean emission scheme will be based on the Korean Climate Change Act proposed by the National Assembly and Government with a cap-and-trade scheme. The national allowances will be allocated by the hybrid system. To establish the national inventory, TRADEMARKS (Telemetering System) and emissions factors are effective for greenhouse gas emissions measurement. It will likewise be effective for the national registry to be implemented via a Korean Integrated Registry, the emissions trading platform via the KRX (Korean Exchange), and the clearing and settlement platform via the KSD (Korean Securities Depository). In other words, the KRX will manage product development and marketing for Korean Carbon Financial Instruments (including commodities, futures, and options contracts) listed and admitted to trading on the KRX. All emissions trades will be standardized and cleared by the KSD.

• The KIPS Transactions:PartD
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• v.9D no.1
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• pp.91-102
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• 2002

We need a component-based system to reflect software changes in user's requirements, to implement a system at a rapid speed as well as to efficiently manage the system in a maintenance phase and to easily change software. Moreover, the component-based system has a merit in development cost. However, existing component development methodology for implement of component-based system is inefficient in object identification for component identification. Moreover, the existing component development methodology also fails to provide any method to identify system component. It merely provides procedures and methods to identify business component focused on a whole system domain. In addition, it has another problem that it considerably relies on developer's experiences and intuitions for component identification. Therefore, according to this paper, RUP (Rational Unified Process) is applied from a requirement analysis phase to an object identification phase in order to improve the inefficiency of object identification. In addition, this paper procedures and methods for system component identification, and identifies business components based on the identified system component, rather than on the whole system domain. This paper also provides and applies cohesion metric and coupling metric so as to overcome the problem that component identification depends on developer's intuitions and experiences. Accordingly, the component identification method proposed in this paper, may identify components more effectively based on facility of object identification, functional reusability of components, traceability, and independence of components.

• KSBB Journal
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• v.11 no.6
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• pp.663-668
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• 1996

In the production of recombinant protein using E. coli, phage lysogen system can be usefully applied for simultaneously achieving protein production at high cell concentration and recovery by cell disruption in the same bioreactor. A major drawback of this system is that the intracellular product and complex broth components are mixed together in culture broth and hence purification efficiency is reduced. With the E. coli double-lysogen system, the expanded bed adsorption is very useful because the pretreatment processes in a routine bioseparation process can be done in a single column operation, and therefore may contribute towards lowering the operating cost of overall recovery/purification process. In the operation of EBA, it has been observed that the change in broth feed volume does not influence much the protein recovery in a tested range. The amount of protein adsorption per mL of resin was increased from $3.44{\times}106unit to 5.28{\times}106unit$ by doubling the column length. By two-fold increase of the column diameter, the ratio of protein concentration in eluent to that in feed was increased from 0.8 to 2.1. It is concluded from the present investigation that the increase of column length and diameter is necessary to enhance the protein adsorption amount per volume of resin and protein concentration in the eluent. The development of resins with various physical properties will be necessary for more extensive application of EBA.

• Korean Journal of Construction Engineering and Management
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• v.17 no.5
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• pp.35-44
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• 2016

Various risk factors are known to be the nature of construction project execution process. These factors lead to potential claims, dispute mediation, arbitration, and litigation which can result in huge loss of money and time. Therefore, it is necessary for construction companies in Korea to improve overall project management capability through the evaluation before entering into the overseas construction market. Also, after examination of the claim and dispute caused by construction project risks, a substantial degree of influence and active preparation for the claim and dispute management should be confirmed via the effect analysis of the each factors. Main claim causes were derived through claim and dispute cases involved with domestic construction projects. As a prediction result of the main claim, 16.1% of the construction change claim, 5.7% of the bad faith claim and 2.7% for the construction delay claim were found to be the portion of the total construction cost. As a result of this analysis, risk management methodology was suggested to improve a project management capability for domestic construction companies through analysis result of the main factors of construction claims.

• Korean Journal of Construction Engineering and Management
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• v.19 no.1
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• pp.43-53
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• 2018

Modular construction can improve construction quality and accuracy through manufacturing process, and it allow massive production and cost savings by repeatedly producing the same unit. In particular, it is possible to reduce the time because the on-site work and the manufacturing process can be carried out at simultaneously. However, according to the modular construction project survey report, there is no significant difference regarding the average construction period between modular construction and conventional construction. This is due to schedule delay problems that occur during construction phase. Therefore, it is necessary to select alternatives to prevent schedule delay during on-site construction progressing. Especially, in case of large-scale modular construction project, on-site module assembly and manufacturing process are performed concurrently. Hence, identification of alternatives should be done at the co-occurrence by taking both manufacturing and on-site work process in to account. In this research, the management factors of large-scale modular construction project were identified through the IDEF0 modeling, and the quantity management model for manufacturing and assembly is developed. This will reduce the schedule delay problem that occurs in the progression on-site work of a large scale modular construction.