• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.172-173
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• 2012

Currently GaN based LED is known to show high internal or external efficiency at low current range. However, this LED operation occurs at high current range and in this range, a significant performance degradation known as 'efficiency droop' occurs. Auger process, carrier leakage process, field effect due to lattice mismatch and thermal effects have been discussed as the causes of loss of efficiency, and these phenomena are major hindrance in LED performance. In order to investigate the main effects of efficiency loss and overcome such effects, it is essential to obtain relative proportion of measurements of internal quantum efficiency (IQE) and various radiative and nonradiative recombination processes. Also, it is very important to obtain radiative and non-radiative recombination times in LEDs. In this research, we measured the IQE of InGaN/GaN multiple quantum wells (MQWs) LEDs with PSS and Planar substrate using modified ABC equation, and investigated the physical mechanism behind by analyzing the emission energy, full-width half maximum (FWHM) of the emission spectra, and carrier recombination dynamic by time-resolved electroluminescence (TREL) measurement using pulse current generator. The LED layer structures were grown on a c-plane sapphire substrate and the active region consists of five 30 ${\AA}$ thick In0.15Ga0.85N QWs. The dimension of the fabricated LED chip was $800um{\times}300um$. Fig. 1. is shown external quantum efficiency (EQE) of both samples. Peak efficiency of LED with PSS is 92% and peak efficiency of LED with planar substrate is 82%. We also confirm that droop of PSS sample is slightly larger than planar substrate sample. Fig. 2 is shown that analysis of relation between IQE and decay time with increasing current using TREL method.

• Industry Promotion Research
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• v.5 no.4
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• pp.55-61
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• 2020

In conducting school violence counseling to solve school violence, this study studied the use of school violence counseling to solve school violence by forming a correct peer relationship. Through this study, we can see that peer relations are an important factor in preventing school violence in school violence counseling. The findings are as follows. First, school violence counseling should first protect and heal victims. The primary goal of school violence counseling should begin with consideration for the victims and be placed on the continuation of the victim's right peer relationship. That's how important peer relationships are. Second, not only victims of school violence counseling, but also perpetrators should be included in the list of counsels. In other words, there may be many cases where counseling is usually focused only on the victim. Therefore, the peer relationship can continue even after school violence, so customized counseling is needed not only for victims but also for perpetrators. Third, for school violence counseling, the recovery of peer relations and insight into life are important. Therefore, the focus should be on self-reflection and the restoration of relations between the parties, not on a disciplined or disciplined, controlled perspective. Fourth, we should recognize the importance of peer relations in school violence and activate the 'old counseling program'. Therefore, school violence counselors should optimize their programs by reflecting on-site needs so that they can act as emotional facilitators, problem solvers, and empathic cultural promoters in their roles. In conclusion, school violence counseling should basically be involved in peer relationships. School violence counseling should develop and implement programs focusing on the formation of proper peer relations in order to eradicate school violence.

• Journal of Digital Convergence
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• v.10 no.6
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• pp.133-140
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• 2012

This study starts from interests on an endeavor of each economy unit, especially the enterprises, for the survival and sustainability of themselves. Competition, how to get it, maintain it and advance it! Agreeing the perceivedness of industries, scholars and public; what the core competition of manufacturer is an competitiveness of product, this study focuses on the PLM system as the key solution for obtaining the competitiveness of product with reviewing the contents and studies of PLM formulated. PLM is highlighted as the one of top tier ICT solution for the product development domain of manufacturing industry today. First of all, this study deals with the opinion of actual work-site and management of our small&medium business for the benefits of PLM based on product development; the impact on the performances of management, which is the key objective of the existence of enterprises. In conclusion, the answers for these questionnaires shows positive perception of actual work-sites and managers for the PLM system. They agree some useful effects on shortening the term and downsizing the cost of product development due to Data integration and Process management, even if they have not full confidence on the effectiveness of the individual functionality of the PLM system.

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.473-480
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• 2014

Upon setting up a dedicated plastic greenhouse for tomato cultivation developed by the Rural Development Administration on the Gyehwa reclaimed land, this study was aimed at analyzing the problems can be occurred in the installation of plastic greenhouse on reclaimed lands as well as finding out solutions for improvement. A relatively cheaper wooden pile was used in the installation in order to supplement the soft ground conditions. Based on the results of ground investigation of the installation site, both the allowable bearing capacity and pulling resistance of the wooden pile with a diameter of 150 mm and a length of 10 m were computed and came out to be 30.645 kN. It was determined that the values were enough to withstand the maximum compressive force (17.206 kN) and the pullout force (20.435 kN) that are generally applied to the greenhouse footing. There are three problems aroused in the process of greenhouse installation, and the corresponding countermeasures are as follow. First, due to the slightly bent shape of the wooden pile, there were phenomenon such as deviation, torsion, and fracture when driving the pile. This could be prevented by the use of the backhoe (0.2) rotating tongs, which are holding the pile, to drive the pile while pushing to the direction of the driving and fixing it until 5 m below ground and applying a soft vibrating pressure until the first 2 m. Second, there exists a concrete independent footing between the column of the greenhouse and the wooden pile driven to the underground water level. Since it is difficult to accurately drive the pile on this independent footing, the problem of footing baseplate used to fix the column being off the independent footing was occurred. In order to handle with this matter, the diameter of the independent footing was changed from 200 mm to 300 mm. Last, after films were covered in the condition that the reinforcing frame and bracing are not installed, there was a phenomenon of columns being pushed away by the strong wind to the maximum of $11m{\cdot}s^{-1}$. It is encouraged to avoid constructions in winter, and the film covering jobs always to be done after the frame construction is completely over. The height of the independent footing was measured for 9 months after the completion of the greenhouse installation, and it was found to be within the margin of error meaning that there was no subsidence. The extent to the framework distortion and the value of inclinometers as well showed not much alteration. In other words, the wooden pile was designed to have a sufficient bearing capacity.

• Journal of the Korea Institute of Building Construction
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• v.17 no.2
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• pp.191-197
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• 2017

The safety nature of construction industry differs from that of manufacturing sector. For instance, accident risk level dramatically varies at each phase of construction process. Korean Occupational and Health Safety Act has been regulated OHS expense and it contributed reducing accident risk and enhancing safety culture for many years. However, although current regulation guides to use OHS expense proportionate to construction progress, it still allows late use of the expense. This study was conducted for the purpose of presenting methods of estimating a step-by-step OHS expense rate required at each construction phase. In order to do provide proper OHS expense schedule, it analysed accident risk of each construction phase by sorting out 1439 cases of construction site fatality reports, and proposed a method of generating appropriate OHS expense scheme according to its construction work progress characteristics. Both linear and sigmoidal S-curve model were used for the analysis, and the latter generally requires earlier use of OHS expense. By comparing the estimated OHS expense use schedule with current criteria, more than 27%p early use of OHS expense is required for the prevention of accident.

• The Korean Journal of Air & Space Law and Policy
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• v.32 no.1
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• pp.385-417
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• 2017

Insurances of space activities are divided into satellite insurance, astronaut insurance and third party liability insurance. Against the background of the rapid development of space commercialization, especially the increasing participation of private entities in space affairs, the present international and domestic mechanisms of space insurance are challenged. As a space-faring state which is in the process of developing space businesses, the regulations of space insurance in China are deserved to be discussed. Satellites insurance is at present well-developed, the "pre-launch", "launch" and "in-orbit" phases of satellites are all possible to be insured by related companies. China created the CAIA in 1997 to provide insurance for Chinese satellites. However, with more private entities start to involve in space as well as satellite industry, the regime established under the framework of CAIA is necessary to be modified, and the mechanism relating to space insurance brokers should be promoted. The astronauts are recognized as the envoy of humankind, and relevant international regulations are made to provide assistance to them in emergency circumstances. From the domestic perspective, astronauts will be fully insured. China creates a particular type of insurance for astronauts. However, once space tourism becomes a business, the insurance of the tourist will be demanded to be created. In order to promote China's space tourism, it is recommended to take the "Astronaut Group Insurance" as an optional model to space tourists, if the tourists are customers of a governmental-owned space company. Once private involvement of providing orbital/suborbital tourism service becomes a reality, new rules are required. Getting a third party liability insurance is deemed as an indispensable precondition for an applicant to get a launch permission. Domestic space laws will include provisions for the third party liability insurance. China's "Interim Measures" of 2002 realizes the importance of third party liability insurance and requires the permit holder to get it before entering the launching site. This regulation is different from the practices of other states. Concerning that China is the sponsor of APSCO, for the purpose of promoting commercial space cooperation, a harmonized approach to domestic law is recommended to be found.

• Journal of the Korea Institute of Building Construction
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• v.16 no.3
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• pp.201-209
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• 2016

This study is to examine experimentally on the engineering properties of fiber reinforced concrete using kenaf(KN) fiber and another organic fibers for comparing test, and propose the usable method of KN fiber as an natural fiber in the concrete industry. It is to select 4 contents(0, 0.3, 0.6 and $0.9kg/m^3$) of KN fiber and 4 organic fibers (Jute, Cellulose, Polypropylene and Nylon). For this study, it is to perform various tests including slump, air content, plastic and drying shrinkage, flexural and tensile strength, carbonation depth for the fiber reinforced concrete according to contents of KN fiber and 4 organic fibers. The results of this study are as follows : In case of KN fiber contents $0.6kg/m^3$, it shows the effective results from increasing concrete strength including flexural and tensile, from decreasing plastic and drying shrinkage, carbonation depth. Also KN fiber is confirmed having excellent performances by comparing with test results of another organic fibers as same contents $0.6kg/m^3$. Therefore, considering concrete test results, cost and environment, KN fiber is proposed as the optimum contents in the range of $0.6kg/m^3$ and an effective fiber materials, and needs to keep up these study on the site application.

• Korean Journal of Construction Engineering and Management
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• v.17 no.2
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• pp.3-11
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• 2016

CM at Risk has been introduced in Korea to keep up with the global standards of construction management and provide a higher quality of cm service in line with a rapid change of the construction industry recently. However, it is widely considered that more time would required to settle down the system due to a lack of understanding towards CM at Risk, shortage of reliability and low capability to manage and undertake CM at Risk. Therefore, this research is analyzed problems of contract types, open book policies, and contract conditions of 33 numbers of projects undertaken by a bespoke domestic construction management firm in this research. Moreover, this research is suggested a method to establish an open book policy of CM at Risk aiming a better customers satisfaction through staff training, simplifying and improving a payment system, and a way to settle down an open book policy by improving a performance management system on site. It's expected that this research will contribute to a more competitive system with more dominating the market and a differentiation of the service so as clients to rely more on the CM at Risk.

• Korean Journal of Construction Engineering and Management
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• v.8 no.1 s.35
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• pp.132-140
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• 2007

There is an increase in interest and investment in high-rise housing as it is perceived to be a new value-added market in the construction industry. In constructing a high-rise housing, the finishing works are executed in accompaniment with many other activities that are progressed repeatedly and spontaneously on each floor. It was reported that the duration of finishing works differs according to the management ability of the executing company and has a significant effect on the entire project duration. We suggest a need to concentrate on important management factors by analyzing the factors affecting the productivity of finishing works based on the site characteristics in high-rise housing. There are various complex productivity-affecting factors including the technical factors involved in planning and managing the processes of finishing works. From the viewpoint of planning and management factors, the importance of productivity-affecting factors was analyzed using the Analytic Hierarchy Process (AHP). A continuous examination of the management of high-importance factors will make it possible to improve productivity by enhancing the understanding of productivity-affecting factors of finishing works and suggesting a practical management direction.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.241-246
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• 2008

With construction industry recession, many construction companies are increasingly conducting the development projects by themselves. However, housing projects requested by developers still stand large portion. Although many studies on feasibility analysis were released, they mainly focused on economic feasibility and lacked research on factors and criterions of overall project. Also, because previous studies overly break downed factors related to project, they rarely used in practice. Therefore, this study developed the feasibility analysis model of housing development projects to help main contractors to easily and effectively decide if it is feasible enough to promote the projects requested by developers, and verified the reliability of the model. In this study, thirty one driving factors were identified under seven different categories and the criterion of each factor was also developed. The survey on important index of each factor found "salability", "economic feasibility", "site location" and "method of raising fund" significant. 3 projects were tested by the model and its results showed resonable reliability.