• Environmental Engineering Research
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• v.18 no.2
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• pp.91-94
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• 2013

Recently Ibadan in southwestern Nigeria has been facing severe water shortage due to the increase of population, social and economic activities. In order to meet the shortfall, attempts to utilize rainwater harvesting (RWH) have been made to provide an alternative source of water supply. A desk study was conducted to review various RWH technologies locally, regionally and globally. A hydrological analysis was also carried out using rainfall data for 30 years from two meteorological stations, with the aim of providing a more sustainable RWH system for water supply to private individuals, organizations, and government agencies. RWH is found to be technically feasible based on the prevailing rainfall pattern with over 90% of households having a rooftop constructed from technically appropriate materials. Results of the study indicate that an average roof of $80m^2$ will collect 82,835 L/yr (45 L/person/day) for a family of five people which is about the required water demand for drinking and cooking purposes. Hence, the capacity of storage tanks and the catchment area required for an all-purpose water supply system based on RWH are quite large. These can be reduced to affordable sizes, by collecting and storing water for cooking and drinking only while non-potable uses are supplemented by water from other sources. However, it must be highlighted that due to the type of roofing material, rainwater should go through proper treatment in order to be used for potable purposes. This study clearly shows that Ibadan city has a good rainwater harvesting potential.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.344-347
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• 2005

The purpose of the study for the development of the technologies of water quality monitoring and contamination protection at water resource aquifer is to secure the groundwater as potable water resources. The results of water analysis as a basis of potable water criteria showed that 30 groundwater samples among 138 samples of small water supply system (21.7%) were exceeded the water criteria. The concentrations of Cl, $NO_3$ and Na for granite area are higher than those of gneiss and metasedimentary rocks of Ogcheon belt area and they are caused by the high vulnerability of groundwater at granite region where the residential area and cultivated land are concentrated. The spatial distribution of components indicated the close relationships between water quality and geology, land use, and topography. The multivariate statistical results showed that the water samples are divided into three groups by geology.

• Corrosion Science and Technology
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• v.11 no.1
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• pp.20-28
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• 2012

Since buried pipes contact the soil directly, corrosion by the soil could be occurred. Recently, some stainless steel pipes after 8 years burial at G area were corroded and leaked. In order to elucidate highly corroded phenomena(its rate was about 0.175 mm/y) of these pipes, the investigation for corrosion environment, soil, stray current's effect, and chemical analysis on the pipes were performed. Most of investigated sites were close to traditional water-closet and showed high moisture and thus those areas could be highly corrosive. In the investigation by two kinds of soil evaluation methods, it was revealed that the soils at G areas were highly corrosive, and moreover the contents of sulfate reducing bacteria in the soils were high. Also, open circuit potentials of many pipes showed different values and its potentials were high positive. Therefore, it was considered that corrosion of buried pipes at G area could be affected by high corrosive soil's environment and stray current corrosion.

• Membrane and Water Treatment
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• v.6 no.1
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• pp.43-52
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• 2015

A small-scale electro-dialysis system was constructed for domestic use. It is composed of six compartments in which five special polystyrene ionic membranes are housed. A series of experiments on the transport of sodium and chloride ions through polystyrene membranes was performed and the effects of electric current and voltage on the pH of water were investigated. This electrodialyser could reduce the NaCl content to an acceptable level (5307 mg/L) when water containing 9945 mg/L of sodium chloride is fed to the electrodialyser. The reduction was by the action of direct current 60 mA/100 mA when a 15 V / 20 V potential is maintained across the membrane. The results showed that the pH of the treated water attained a value in the range of 7-8, with the chloride concentration of 5307 mg/L when the voltage was in the range of 20 volts. This was achieved when two of the small-scale electro-dialysers were placed in series and the solutions from the respective compartments were mixed. This is considered useful because this complies to the requirement of drinking water standard both in terms of chloride and pH. Therefore, this type electrodialyserhas the potential for domestic uses in isolated houses where potable water supply is not available.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.1032-1036
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• 2006

In this study, we implement the potable blood gas analyzer measuring pH, $pCO_2\;and\;pO_2$ of the arterial blood. The implemented system by this study is divided into hardware and software part and also the hardware portion is parted by mechanism and electronic circuit mit. The system program is composed of operating, washing, correcting and measuring program. And to correct the system, two-point calibration method is used, one-point calibration method is also added for more accuracy, and system program is coded. For verifying the implemented system, We examine to response property of each electrode. And evaluate accuracy of the system using standard reagent and was construed as statistical.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.94-100
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• 2024

Recently, as interest in personal hygiene has increased due to the community spread of COVID-19 and variant viruses, fixed and potable UV germicidal equipment to sterilize indoor spaces and hand-held UV germicidal equipment to sterilize household items such as masks and mobile phones are continuously being developed and sold. However, the development and sales of the product are difficult because appropriate testing methods have not yet been established. In this situation, if an uncertified product is distributed in the market, it can cause serious harm to consumers. In this study, we investigate the photobiological risks and safety devices against UV exposure of UV germicidal equipment distributed domestically, and propose appropriate test methods for portable UV germicidal equipment based on the research results.

• Journal of Biomedical Engineering Research
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• v.24 no.5
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• pp.427-434
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• 2003

In this paper, we present a speech-based Environmental Control System(ECS) and its application. In the concrete, an ECS using the speech recognition and an portable wheelchair lift control system with the speech synthesis are developed through the simulation and the embodiment. The developed system apply to quadriplegic man and we evaluate the result of physical effect and of mental effect. Speech recognition system is constructed by real time modules using HMM model. For the clinical application of the device, we investigate the result applied to 54-years old quadriplegic man during a week through the questionnaires of Beck Depression Inventory and of Activity Pattern Indicator. Also the motor drive control system of potable wheelchair lift is implemented and the mechanical durability is tested by structural analysis. Speech recognition rate results in over 95% through the experiment. The result of the questionnaires shows higher satisfaction and lower nursing loads. In addition, the depression tendency of the subject were decreased. The potable wheelchair lift shows good fatigue life-cycle as the material supporting the upper wheelchair and shows the centroid mobility of safety. In this paper we present an example of ECS which consists of real-time speech recognition system and potable wheelchair lift. Also the experiments shows needs of the ECS for korean environments. This study will be the base of a commercial use.

• Korean Journal of Food Science and Technology
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• v.34 no.5
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• pp.862-866
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• 2002

This study was performed to analyze aroma pattern of Panax species (Korean Panax ginseng C.A. Meyer, Chinese Panax ginseng C.A. Meyer, Panax quinquefolium L, and Panax notoginseng F.H. Chen) by the PHGC (potable handheld gas chromatograph). Ratios of several peak areas in chromatogram of derivative parrtern were as follows. If ratio of Korean Panax ginseng was 1, Panax notoginseng was $0.030{\sim}0.674$, Chinese Panax ginseng was $0.005{\sim}0.212$ and panax quinquefolium was $0.241{\sim}0.871$. Ratios of peak area at $Rt_{20.02}$ were that if Korean panax ginseng was 1, Chinese Panax ginseng was 0.212, Panax quinquefolium was 0.343 and Panax notoginseng was 0.065. Ratios also of peak area at $Rt_{21.70}\;and\;Rt_{24.90}$ showed clear difference among aroma patterns of Panax specie cultivars. Flavor component at $Rt_{26.15}$ was not detected in Panax quinquefolium and Panax notoginseng but in Korean Panax ginseng and Chinese Panax ginseng. Ratios of peak area at $Rt_{26.15}$ were that if Korean Panax ginseng was 1, Chinese Panax ginseng was 0.185. And so habitat of Panax species cultivars was discriminated. Cultivar and habitat of dried panax species was remarkably distinguised by the chromatogram of frequency pattern, derivative pattern and visual pattern using olfactory images known as Vapor $print^{TM}$.

• The Magazine of the IEIE
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• v.42 no.7
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• pp.45-53
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• 2015

Power 소자 기술은 digital & mixed signal device와 on-chip 구현을 위해서 CMOS 공정에 대한 기본 이해가 필요하다. CMOS 공정 기반 위에 power device 공정을 추가하면서 다양한 operation voltage의 power 소자를 구현하고, passive device 들을 동일 공정에서 구현하여 다양한 components 들로 power IC 제품을 design 할 수 있도록 modular process를 제공하는 것이 중요하다. 또한 power device로 주로 사용되는 LDMOS 소자에 대한 performance 개선을 위해 simulation을 통해 key device parameter들의 특성을 예측하고, 구조를 설계하는 것이 Si process 전에 중요한 일 중의 하나이다. 아울러 power management가 potable power, consumer electronics 및 green energy에서 가장 빠르게 성장하는 분야이므로, 차별화된 power 소자 기술을 확보하여 급변하는 시장 환경에 대응하는 것이 필요하다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.215-218
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• 2002

본 연구는 휴대 전자기기용 전원으로 사용 가능한 직접 메탄올 연료전지(Direct Methanol Fuel Cell)의 조건에 따른 성능 특성에 관하여 연구를 하였다. 메탄올은 사용함에 안전할 뿐 아니라 에너지 밀도 또한 월등함으로 DMFC를 통해 전기에너지로 변환시킬 경우 휴대용 기기의 전원으로 사용함에 있어서 기존의 베터리를 대체할 가능성이 있는 에너지원으로 연구되어지고 있다.(중략)