• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.2
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• pp.62-67
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• 2002

This paper - following 'Development of multi-purpose marine waste cleaning systems for the shallow waters (Part I : preliminary conceptual design)'- describes on the system development and the sea trial performance evaluation(Cho[2003]). The multi-functional seabed waste collecting system and the towing hook system were developed. The maximum working depth of these systems are 15 and 100 meters, respectively(MOMAF[2001]). For the multi-purpose use to collect the marine waste, this system contains floating waste collecting device for the waste on seawater and remained waste collecting device for the waste on seabed, while steel wire cutting system is added for higher efficiency In order to evaluate the system performance, the prototype of multi-functional system was constructed and the sea trial test at shallow water were carried out. As a result, this system operated well with safe and without any interaction so that the developed systems are practicable and applicable.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2155-2161
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• 2016

Since Korea is highly dependent on energy imports, it has been making efforts to save energy resources by enacting laws to promote resource saving and recycling. Recently, as a part of recycling of empty bottles, a bottle unattended collecting machine has been installed in the big shopping mall in the metropolitan area. However, there is no commercialization of the unattended collecting machine in Korea and the smart device application for providing information on empty bottle recycling is not yet provided. In this paper, we have designed and constructed a bottle recycling information management system to promote resource recycling. The manager has built a homepage that can manage the information of the empty bottle and the a bottle unattended collecting machine. Also, many people with smart devices can easily access bottle recycling information by using camera and barcode search and label search.

• Journal of the Korean Solar Energy Society
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• v.25 no.3
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• pp.11-18
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• 2005

The Korea Institute of Energy Research(KIER) has begun collecting horizontal global insolation data since May, 1982 at different locations. Because of a poor reliability of existing data, KIER's new data will be extensively used by the solar system users as well as by research institutes. But the quality of solar insolation data is not always good. This reports on an attempt to identify systematic error in such data using clear-day analysis for data rehabilitation. Clear-day analysis is successful in uncovering solar insolation data of questionable quality. It is not proven that rehabilitation process can improve the quality of data for daily or monthly means, but it is suggested that the method can be used to improve the quality of data for monthly means of several years for use in many applications of solar energy planning. Earlier studies finding a maximum ETR of about 0.80 are confirmed.

• Journal of the Korean Solar Energy Society
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• v.27 no.2
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• pp.53-59
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• 2007

Knowledge of the solar radiation components are essential for modeling many solar photovoltaic systems. This is particularly the case for applications that concentrate the incident energy to attain high photo-dynamic efficiency achievable only at the higher intensities. In order to estimate the performance of concentrating PV systems, it is necessary to know the intensity of the beam radiation, as only this component can be concentrated. The Korea Institute of Energy Research(KIER) has began collecting solar radiation component data since August, 1996. KIER's component data will be extensively used by concentrating PV system users or designers as well as by research institutes.

• Journal of the Korean Solar Energy Society
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• v.31 no.1
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• pp.87-92
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• 2011

Since the atmospheric clearness index is main factor for evaluating atmosphere environment, it is necessary to estimate its characteristics all over the major cities in Korea. We have begun collecting clearness index data since 1982 at 16 different cities and considerable effort has been made for constructing a standard value from measured data at each city. The new clearness data will be extensively used by evaluating atmospheric environment as well as by solar application system designer or users. Yearly mean 64% of the atmospheric clearness index was evaluated for clear day all over, and significant difference of horizontal global insolation is observed between 1982~1986 and 1987~1991, 1992~1996, 1997~2001, 2002~2009 through 16 different cities in Korea.

• Journal of the Korean Solar Energy Society
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• v.33 no.2
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• pp.56-63
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• 2013

Daylighting system is an alternative lighting system using daylight collecting device, light transformer and light diffuser. In this paper, we developed a daylighting system in which the collecting device composed by dual parabolic reflectors, the silica optical fiber adapted to the light transformer and light diffuser made of the polyglass square sheet. We have estimated the system efficiency and general color rendering index(Ra) of the developed system. The system efficiency measured to 23.8% and Ra was revealed as 95. Ra number of the developed system is bigger than the number(65) of the previous fresnel lens based sunlight collector.

• Journal of the Korean Solar Energy Society
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• v.39 no.2
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• pp.45-55
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• 2019

More than 76% of the detached houses in Korea are over 20 years old. These old detached houses have poor energy efficiency. According to the 2017 Housing Census (Statistics Korea), more than 50% of low-income families live in detached houses. Therefore, the improvement of energy efficiency in old detached houses is needed from the viewpoint of energy welfare. The general method of building energy modelling for the verification of energy efficiency is based on the construction year data of "Building Design Criteria for Energy Saving" due to the cost and time involved in collecting the thermal performance data of buildings. There is poor accuracy with the deterioration of long-term aging of building materials. Also, the selection of alternatives for energy performance improvement is based on the items to be applied, not a performance improvement goal. It is difficult to calculate energy performance that reflects variations in various parameters with dynamic energy simulations. In this study, the influence of long-term aging is used to accurately predict the energy performance of old detached houses. The building energy modelling method is called ENERGY#, which is a static analysis method based on ISO13790. Energy performance is evaluated by a combination of input variables including building orientation, insulation of walls and roof, thermal performance of windows and window/wall ratio, and infiltration rate. Finally, this study provides a way to determine alternatives that meet energy performance improvement goals.

• Journal of the Korean Solar Energy Society
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• v.33 no.6
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• pp.12-18
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• 2013

Domestic solar hot water system can be divided into a passive type and an active type. In a passive type the storage tank is horizontally mounted immediately above the solar collectors. No pumping is required as the hot water naturally rises into the storage tank from the collectors through thermo-siphon flow. While, in an active type the storage tank is ground- or floor-mounted and is below the level of the collectors; a circulating pump moves water or heat transfer fluid between the storage tank and the collectors. We installed two types solar hot water systems consisting of the same storage tank and collectors at the same place, and were measured and compared typical operating characteristics under the same external conditions. In particular, the daily system performance was presented through the stirring test after the sunset. The results show that the amount of solar radiation obtained for an active type were less than a passive type on a cloudy day, because the operation of the circulation pump stops frequently took place on that day. However, on a sunny day, depending on the stable operation of the circulation pump, the amount of solar radiation obtained for an active type were increased than a passive type.

• Journal of Ocean Engineering and Technology
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• v.23 no.6
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• pp.1-6
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• 2009

An Overtopping Wave Energy Convertor (OWEC) is an offshore wave energy convertor used for collecting overtopping waves and converting the water pressure head into electric power through hydro turbines installed in a vertical duct affixed to the sea bed. A numerical wave tank based on the commercial computational fluid dynamics code Fluent is established for the corresponding analysis. The Reynolds Averaged Navier-Stokes equation and two-phase VOF model are utilized to generate the 2D numerical linear propagating waves, which are validated by the overtopping experiment results. Calculations are made for several incident wave conditions and shape parameters for the overtopping device. Both the incident wave periods and heights have evident effects on the overtopping performance of the OWEC device. The computational analysis demonstrates that the present overtopping device is more compatible with longer incident wave periods.

• Annual Conference of KIPS
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• 2012.04a
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• pp.607-608
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• 2012

Data aggregation is a fundamental problem in wireless sensor networks which attracts great attention in recent years. Delay and energy efficiencies are two crucial issues of designing a data aggregation scheme. In this paper, we propose a distributed, energy efficient algorithm for collecting data from all sensor nodes with the minimum latency called Delay-aware Power-efficient Data Aggregation algorithm (DPDA). The DPDA algorithm minimizes the latency in data collection process by building a time efficient data aggregation network structure. It also saves sensor energy by decreasing node transmission distances. Energy is also well-balanced between sensors to achieve acceptable network lifetime. From intensive experiments, the DPDA scheme could significantly decrease the data collection latency and obtain reasonable network lifetime compared with other approaches.