수격펌프의 효율성 및 현장 적용성 평가

이수형,윤희성,김동훈,신에스더,김용철,고경석,하규철,Lee, Soo-Hyoung,Yoon, Heesung,Kim, Dong-Hun,Shin, Esther,Kim, YongCheol,Ko, Kyung-Seok,Ha, Kyoochul 대한자원환경지질학회 2016 자원환경지질 Vol.49 No.3

본 연구는 수격펌프를 이용하여 용수 공급의 가능성과 효율성을 평가하기 위하여 수행되었다. 연구지역은 경상북도 상주시 화남면 임곡리로 과거 석탄개발에 사용된 갱도로부터 지속적으로 지하수 유출이 발생하고 있다. 유출되는 지하수는 일평균 약 $260m^3/day$의 수량을 가지는 것으로 파악되었다. 수격펌프는 수격현상을 이용하여 전력없이 공급원으로부터 고도차(압력)에 의해 물의 일부를 높은 곳으로 이송시키는 펌프이다. 수격펌프의 효율성을 파악하기 위해 수격펌프와의 고도차에 따라 3지점(${\Delta}h=19m$ (1지점), 30 m (2지점), 40 m (3지점))에서 유량을 측정하였다. 1지점에서는 약 $8.6{\sim}10.8m^3/day$, 2지점은 약 $3.98{\sim}4.39m^3/day$ 그리고 3지점에서는 약 $2.35{\sim}2.59m^3/day$의 물을 운반할 수 있는 것으로 파악되었다. 이번 연구를 통해 수격펌프가 산간지역 등에서 전력없이 물공급 시스템에 활용할 수 있을 것으로 파악되었다. This study was conducted to evaluate the applicability and efficiency of water supply using hydraulic ram pump. Study area is the Imgok-ri, Hwanam-myeon, Sanju-si, Kyeongsangbuk-do. There is an abandoned coal mine, where groundwater is discharged from its entrance with a flow rate of approximately $260m^3/day$. Hydraulic ram pump uses the waterhammer phenomenon and utilizes the power of falling water for pumping part of that water to a higher elevation than the water sources without electric power. To determine the efficiency of hydraulic ram pump, the flow rate was measured at three points according to the altitude difference (${\Delta}h=19m$ (point 1), 30 m (point 2), 40 m (point 3)). Flow rate measured at 1, 2, and 3 were about $8.6{\sim}10.8m^3/day$, $3.98{\sim}4.39m^3/day$, and $2.35{\sim}2.59m^3/day$, respectively. The current results suggested that, hydraulic ram pump could be applicable for the water supply system in mountain areas without external power supply.

지진에 의한 제주도 지하수위 변동 분석 (2010년 인도네시아 규모 7.7 지진)

이수형,함세영,하규철,김용철,정범근,고경석,고기원,김기표,Lee, Soo-Hyoung,Hamm, Se-Yeong,Ha, Kyoo-Chul,Kim, Yong-Cheol,Cheong, Beom-Keun,Ko, Kyung-Seok,Koh, Gi-Won,Kim, Gee-Pyo 한국지하수토양환경학회 2011 지하수토양환경 Vol.16 No.2

This study was conducted to investigate the relationship between groundwater level change and a large earthquake using the data of groundwater and seawater intrusion monitoring wells in Jeju Island. Groundwater level data from 13 observation wells were analyzed with a large earthquake. The Earthquake occurred at Sumatra, Indonesia (Mw = 7.7) on 13 June 2010, and groundwater level anomalies which seems to be related to the Earthquake were found in 6 monitoring wells. They lasted for approximately 16~27 minutes and the range of groundwater level fluctuations were about 1.4~2.4 cm. Coefficient of determination values for relationship between groundwater level change and transmissivity, and response time were calculated to be $R^2$ = 0.76 and $R^2$ = 0.96, respectively. The study also indicates that the high transmissivity of aquifer showed the high goundwater level changes and longer response time.

CPA분석을 이용한 기동하는 수신기에서의 표적 속도 추정기법

이수형,김정수,이균경,Lee, Su-Hyoung,Kim, Jeong-Soo,Lee, Kyun-Kyung 한국음향학회 2009 韓國音響學會誌 Vol.28 No.4

일정한 주파수의 음향신호를 발생시키는 표적이 기동할 때 한 개의 고정된 센서에서 관측된 신호의 주파수는 시간에 따라 도플러 변이가 발생한다. 이러한 도플러 변이 현상을 이용한 기존의 CPA (Closest Point of Approach) 분석으로 센서 수신기에 표적이 최단거리로 근접했을 때의 시간, 거리, 속력 그리고 실제 신호의 중심주파수를 추정할 수 있다. 본 논문에서는 고정된 단일 센서 대신에 일정한 속도로 기동하는 배열센서 수신기에서 주파수뿐만 아니라 표적의 방위각을 관측하여 이로부터 표적의 실제 기동속도를 추정하는 기법을 제안한다. 그리고 제안한 기법의 성능검증을 위해 오차 분석 및 모의 실험을 수행하였다. A conventional Closest Point of Approach (CPA) analysis allows a non-maneuvering moving source that is radiating a constant frequency tone to be located using doppler shifted frequency measurements obtained by a stationary receiver. The original frequency, relative speed of the target, time at the CPA, and range from the CPA to the sensor are estimated by the conventional CPA. However, this paper proposes a new CPA analysis that allows the motion parameters of a target to be estimated using the bearing and frequency measurements obtained by a moving receiver that has a constant velocity. The validity of the proposed estimation scheme is confirmed through a performance analysis and simulation study.

모바일 기기 및 휴대용 환경 측정기를 이용한 데이터 수집 및 관리용 모바일 앱 및 서버 시스템 구현

이수형(Su Hyoung Lee),김창수(Chang Soo Kim) 한국정보기술학회 2021 한국정보기술학회논문지 Vol.19 No.9

Water is one of the most important environmental resources for maintaining healthy life and its accurate assessment is critically important. In this paper, we propose an effective method to use a lab-made portable environmental meter for water quality assessment that is easily available to the public. The portable meter is to measure the cleanness of water and has a connectivity to smart devices including cellphones, tablets and laptops, etc. via Bluetooth. A mobile app based on Ionic Framework for data collection and management using the meter is developed. In addition, a database for the collected data is built utilizing MySQL, and a web server is implemented to utilize the data. A simple field test is successfully conducted to evaluate the performance of data collection and management using the developed mobile app and server.

RMP 기법을 사용한 복수 분산전원 시스템의 용량선정 최적화 방법

이수형(Soo-Hyoung Lee),박정욱(Jung-Wook Park) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.7

전력설비의 증설 없이 지속적으로 증가하는 부하는 전력계통의 안정성 및 신뢰성 확보를 어렵게 하며, 송전으로 인한 전력손실을 급격하게 증가시킨다. 비용 및 환경적인 측면에서, 분산전원은 야기되는 문제의 해결책이 될 수 있으며, 분산전원의 연계로 얻어지는 전력계통의 안정도 및 신뢰도 향상과 전력손실 감소는 연계되는 분산전원의 용량에 의해 결정이 된다. 따라서 최적용량 선정문제는 분산전원을 전력계통에 연계하기 위해 필수적으로 선행되어야 할 과제이나, 현재까지 이를 명확하게 해결한 체계적 방법은 개발되지 않았다. 이번 연구는 reduced multivariate polynomial (RMP)모델을 이용한 계통연계 복수 분산전원 시스템의 최적용량 선정 방법을 제안하며, 최적용량 선정을 위해 요구되는 시스템 자원을 획기적으로 감소시킨다.

측정오차로 인한 계통 영향 최소화를 위한 전력 민감도 기반 STATCOM 운영

이수형(Soo Hyoung Lee) 대한전기학회 2021 전기학회논문지 P Vol.70 No.3

In recent, renewable energy has received considerable attention worldwide due to the ‘Global Warming of 1.5oC’. There are still many challenges to be solved, however, to increase the penetration rate of renewable energy in the power system. Above all, most of the renewable energy DGs even aggravate the grid voltage from the intermittency of variable renewable energy sources rather than regulate the voltage as the conventional generators did. This paper proposes power-sensitivity-based STATCOM operation to minimize grid impact from measurement noise. The proposed method realizes seamless control of the voltage by compensating with the reactive power when the power generation or load consumption is changed. To achieve the proposed method, the reactive power references of the STATCOMs are operated based on the power sensitivities. As the result, it can be accomplished that constant voltage control even if high penetration of renewable energies. The proposed method is verified with several case studies that are based on a microgrid with practical data from a real island power system. The verification is carried out using the power system computer aided design and electromagnetic transient including DC (PSCAD/EMTDCTM) simulation software.

전력손실을 고려한 분산전원의 최적 위치 및 용량 선정

李洙衡(Soo-Hyoung Lee),朴正旭(Jung-Wook Park) 대한전기학회 2008 전기학회논문지 Vol.57 No.4

Increase in power consumption can cause a serious stability problem of an electric power system without construction of new power plants or transmission lines. Also, it can generate large power loss of the system. In costly and environmentally effective manner to avoid constructing the new infrastructures such as power plants and transmission lines, etc, the distributed generation(DG) has paid great attentions so far as a solution for the above problem. Selection of optimal location and size of the DG is the necessary process to maintain the stability and reliability of existing system effectively. However, the systematic and cardinal rule for this issue is still open question. In this paper, the method to determine optimal location of the DG is proposed by considering power loss when the DG is connected to an electric power grid. Also, optimal size of not only the corresponding single DG but also the multi-Des is determined with the proposed systematic approach. The IEEE benchmark 3D-bus test system is analyzed to evaluate the feasibility and effectiveness of the proposed method.

수확 후 키토산-칼슘 침지와 고농도 CO₂처리에 따른 참외 과실 세포벽 변화

이수형(Soo-Hyoung Lee),범수정(Xiujing Fan),민정호(Jeong Ho Min),황용수(Yong-Soo Hwang) 한국원예학회 2015 한국원예학회 학술발표요지 Vol.2015 No.5

옥천군 일대 수문시스템 평가를 위한 하천 유량 및 수질 분석

이수형(Soo-Hyoung Lee),문상호(Sang-Ho Moon),기민규(Min-Gyu Ki),하규철(Kyoochul Ha) 대한지질학회 2015 대한지질학회 학술대회 Vol.2015 No.10

인버터의 직류 고장전류 차단 방법

이수형(Soo Hyoung Lee) 대한전기학회 2019 전기학회논문지 Vol.68 No.8

Inverter based electrical devices are used for various applications in power system, such as renewable energy based generation, energy storage system (ESS), static compensator (STATCOM), high voltage direct current transmission (HVDC), etc. All of the inverter based devices can interrupt AC fault current much faster than mechanical AC circuit breakers by opening electronic switches, such as insulated gate bipolar transistor (IGBT) and metal oxide semiconductor field effect transistor (MOSFET). By contrast, DC fault current bypasses the electronic switches through anti-parallel diode regardless of the switch states. This paper describes a simple DC fault current interruption topology based on ultrafast disconnectors. The proposed topology can interrupt the DC fault current within at most one cycle. Its performance is verified based on electromagnetic transient (EMT) simulation using power system computer aided design /electromagnetic transients including direct current (PSCAD™/EMTDC™).