• 한국공작기계학회논문집
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• 제17권2호
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• pp.90-96
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• 2008

A pneumatic system was proposed to evaluate displacement accuracy of the pneumatic actuator without external load and to analyze capability of integration of the proposed valve system. The proposed pneumatic system consisted of a combination of pneumatic valves, two proximity sensors, and a programmable logic controller(PLC). The position controller is based on the PLC controller connected with the proximity sensors. Displacement accuracy of the pneumatic cylinder stroke was tested by varying air pressures of the supply and discharge-side and strokes of the pneumatic cylinder. The displacement accuracy of the pneumatic cylinder stroke increased as the supply and discharge side of air pressure increased at the stroke length of 133mm. Also the displacement accuracy increased as the stroke length increased with a fixed supply and discharge side of air pressure of the pneumatic cylinder as 3.5 and $4.5kg/cm^2$, respectively. The most accurate displacement of the pneumatic cylinder(i.e., standard deviation of 0.01 mm) was obtained at the supply and discharge side of air pressure of 4.0 and $5.0kg/cm^2$, respectively, and strokes of 170 and 190 mm among arbitrarily selected supply and discharge side air pressures and strokes.

• 한국산학기술학회논문지
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• 제8권6호
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• pp.1363-1368
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• 2007

태양광 발전이나 풍력발전과 같은 신재생 에너지를 효과적으로 사용하기 위해서는 고성능 축전지 충 방전 컨트롤러가 필수적이다. 본 논문에서는 PIC 마이크로프로세서를 사용한 태양광 발전 축전지 충방전 컨트롤러를 설계, 제작하였다. 컨트롤러의 핵심이 되는 제어부는 정확하고 안정된 동작을 위해서 산업용 마이크로프로세서인 PIC16C711를 사용하였고 제어프로그램은 CCS-C 언어로 작성하였다. 사용자의 편리성을 향상시키기 위해 낮에도 축전지 전원을 사용할 수 있도록 설계하였으며, 전류 조정 기능으로 향후 신소재 개발에 따른 다양한 축전지에 대응할 수 있게 하였다.

• 전기학회논문지
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• 제63권10호
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• pp.1461-1466
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• 2014

GIS(Gas Insulated Switchgear) is important power apparatus which have strong dielectric strength, supply electric power and is a part of the power system. Most substation type is configured as GIS. Recently, because of continuous increasement of GIS demand resulted from high quality & big capacity of electric power, the necessity of the preventive & diagnosis system is being expanded gradually. GIS partial discharge occurred on the UHF band is detected effectively by the method to IEC 60270 that recommend to be able to detect the apparent minimum discharge, 5 pC. Additionally, the UHF sensor should be installed to detect PD signal if Partial discharge signal, 5 pC occur in every part of GIS. Currently PD diagnosis system applying UHF sensor for GIS with various voltage level like 154 kV, 345 kV, 765 kV have been operated. And it is necessary to measure and analyze insulation breakdown phenomenon of inside GIS exactly. In this paper, we proposed Fat-dipole patch UHF sensor that is developed and more sensitive, excellent wide-range characteristic than the exising UHF sensor. And we performed KERI (Korea Electrotechnology Research Institute) reference test, which showed the excellent result for the all tests.

• 한국정보통신학회논문지
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• 제19권4호
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• pp.933-939
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• 2015

일반전원이 공급되지 않은 광파표지는 태양광을 이용한 전력공급시스템을 사용하고 있다. 이러한 전력공급시스템에서는 충 방전조절기의 역할이 매우 중요하다. 항로표지의 효과적인 관리를 위해 도입된 IT기술(AIS통신 등)은 광파표지에 전력을 사용하는 장치를 추가하게 됨으로써 충 방전조절기의 중요성이 증가하고 있다. 현재 운용되는 충 방전조절기는 항로표지 내부에 부착되어 해상환경에 따라 점검 및 확인하는데 어려움이 있다. 이를 해결하기 위해서 본 논문에서는 충 방전조절기에 블루투스 모듈을 구성하여 근거리 점검이 가능한 모니터링 시스템을 제안하였다. 제안한 시스템은 도입 비용이 적고, 구성이 간편하여 다양한 항로표지에 응용가능한 장점이 있다. 또한 근거리에서 충 방전조절기의 실시간 상태정보를 확인할 수 있어서 점검 비용을 절감하고, 점검 시 발생 가능한 위험요소를 줄일 수 있다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권5호
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• pp.53-66
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• 2011

Groundwater which infiltrated in recharge areas discharges in the forms of evapotranspiration, baseflow to streams, groundwater abstraction and eventually flows into the sea. This study characterized radon-222 concentration and electrical conductivity (EC) in coastal groundwater discharge, well groundwater, Ilkwang Stream water, and seawater in the coastal area of Busan Metropolitan City and subsequently estimated groundwater discharge rate to the sea. The median value of Rn-222 concentration is highest in well groundwater (18.36 Bq/L), and then decreases in the order of coastal groundwater discharge (15.92 Bq/L), Ilkwang Stream water (1.408 Bq/L), and seawater (0.030 Bq/L). The relationship between Rn-222 concentration and EC values is relatively strong in well groundwater and then in seawater. However, the relationship is not visible between coastal groundwater discharge and Ilkwang Stream water. The groundwater discharge rate to the sea is estimated as $3,130m^3$/day by using radon mass budget model and $16,788m^3$/day by using Darcy's law.

• 물과 미래
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• 제29권3호
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• pp.153-161
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• 1996

최근에 도시화 된 산본천 유역을 대상으로 한 유출 해석이다. 실측한 각종 자료를 유출해석 모형인 ILLUDAS를 이용하여 도시화에 따른 첨두유량과 총유출량의 연구를 분석하였다. 도시하천에서 첨두유량의 증가는 도시화에 따른 하정비가 가장 큰 영향이 있는 것으로 판단된다. 첨두유량은 강우 지속시간이나 재현기간에 따라 조도계수 n=0,04일 경우에 최대 10%까지, n=0.015일 경우는 7~16%이었으며, 또한 자연하도(n=0.04)에서 계획하도(n=0.015)로 변화하면 첨두유량은 51~158%까지 큰 폭의 증가를 보였다. 일반적으로 호우시 홍수첨두유량은 증가하지만 도시유역의 경우는 배수계통의 정비로 유속이 증가하면서 하천 수위는 오히려 감소하는 것으로 나타났다.

• Ocean and Polar Research
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• 제40권4호
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• pp.191-202
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• 2018

In this study we conducted a weekly monitoring exercise at a fixed station in the saltwater zone during the dry season (Jan-Mar, 2013) and wet season (Jun-Aug, 2013) to understand the fluctuations in phytoplankton communities and environmental factors in the Youngsan River estuary altered by a dike constructed in the coastal area. Phytoplankton communities displayed seasonality; diatoms were dominant during the dry season whereas dinoflagellates were dominant during the wet season. T-test analysis showed that water temperature was significantly different between the seasons whereas freshwater discharge from the dike was not significantly different. This suggests that seasonal variations of phytoplankton are more likely affected by water temperature than freshwater discharge. However, a short-term fluctuation was also observed in response to freshwater discharge; freshwater species appeared during or after the discharge in the dry and wet seasons and blooms of harmful species developed after the discharge. Phytoplankton communities may be affected by changes in physical factors such as turbidity and salinity and nutrient supply resulting from freshwater discharge. Especially, the nutrient supply may directly contribute to the harmful algal blooms (HABs) composed of dinoflagellates which can adapt to low salinity after freshwater discharge.

• 한국항만학회지
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• 제14권3호
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• pp.361-371
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• 2000

A demand of marine outfall system has been much increased for the effective disposal of the wastewater due to population and industrial development at the coastal areas. The outfall system discharges primary or secondary treated effluent into the coastline, or at the deep water, or between these two. The discharge is carried out by constructing a pipeline on the sea bed with a diffuser or with a tunnel, risers and appropriate. The effluent, which has a density similar to that of fresh water, rises to the sea surface forming plume or jet, together with entraining the surrounding salt water and becomes very dilute. Thus there have been growing interests about plume behaviour around the outfall system. Plume or jet discharged from single-port or multi-port diffuser might cause certain impacts on coastal environment. Near field mixing characteristics of discharged water field using CORMIX model have been studied for effective outfall design various conditions on ambient current, depth, flow rate, effluent concentration, diffuser specification, port specification etc.. This kind of analysis is necessary to deal with water quality problems caused by the ocean discharge. The analyzed result was applied to the Pusan Jungang effluent outfall system plan.

• 전자공학회논문지
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• 제51권8호
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• pp.195-201
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• 2014

본 논문에서는 도광판(LGP, Light Guide Panel)의 미세먼지 세정을 위해 건식 점착롤 제진과 코로나 대전을 이용한 제전(ESD, electrostatic discharge) 방식을 적용한 건식 세정 장치를 개발한다. 이를 위해 점착롤 제진과 제전 방식을 혼합 적용할 수 있는 세정 메커니즘을 설계하고, LGP를 자동으로 로딩/언로딩 및 이송할 수 있는 장치를 설계하고 구현한다. 그리고 이물질 및 미세먼지 세정 실험을 통해 개발된 시스템이 안정적으로 동작함을 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제6권1호
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• pp.111-118
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• 2011

In recent years, various types of partial discharge (PD) methods such as capacitive, inductive, electromagnetic, and acoustic coupling techniques have been developed for diagnosing rotating machines. An electromagnetic (EM) probe, which is an inductively coupled type of sensor, is required for detecting corona and internal discharges during off-line tests. In this study, a new technique for enhancing the measurement sensitivities for corona and internal discharge based on an EM inductive position sensor is proposed. An EM probe that winds wires around horseshoe-shaped and cylindershaped ferrites as helices is designed and optimized for the implementation of off-line PD monitoring of the stator winding of a rotating machine. The measurement system based on this design is implemented, and it is verified from the results of the experiment performed in this study that the probe provides similar performance as existing commercial products.