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      • 전력 계통 해석을 위한 InTouch HMI 구현

        안창한(Chang-Han Ahn),백영식(Young-Sik Baek),이상덕(Sang-Deok Lee),장병훈,이근준(Geun-Joon Lee),이현철(Hyun-Chul Lee) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.7

        전력계통 해석 분야는 소프트웨어를 사용하여 시뮬레이션한 결과에 HMI를 도입하여 기존의 공급자 중심에서 사용자 중심으로 변하고 있다. 본 논문에서는 조류계산 엔진 소프트웨어인 PSS/E를 사용하여 시뮬레이션을 했다. 그 결과값을 Python으로 코딩한 프로그램을 이용 SQL 데이터베이스로 옮겨 주었다. 최종적으로 사용자의 편의에 맞게 구현된 InTouch에 데이터를 나타나게 함으로써 HMI를 구현하였다.

      • KCI등재

        전력계통 안정화를 위한 전압보상설비 운용 방안

        안창한(Chang-Han Ahn),백영식(Young-Sik Baek) 대한전기학회 2015 전기학회논문지 Vol.64 No.4

        A new algorithm for a coordinative control method is proposed with respect to voltage control and system stabilization of local substations. This is accomplished using control cooperation between a static synchronous compensator (STATCOM) and the existing voltage compensation equipment in the steady state and emergency state of a power system. A real-time system analysis was developed by combining a system analysis program with InTouch, which has primarily been used in factory automation for verification. PSS/E was used for the load flow calculation software, Python for language, Intouch as an HMI program, and MS SQL for the database. To test this system, the system in the vicinity of the Migeum and the Migeum substations was modeled and simulated.

      • KCI등재

        비상상태 전압제어를 위한 무효전력보상설비의 최적 운용

        안창한(Chang-Han Ahn),백영식(Young-Sik Baek) 대한전기학회 2015 전기학회논문지 Vol.64 No.5

        This paper proposes a method for solving running cost problem by minimizing switching reactive power compensation devices. An objective function was modeled by calculating the weighting value of cost, and a solution was derived using ILP. This paper suggests optimal coordinative control method between FACTS, Shunt Reactors, Capacitors and OLTC. Therefore, it is valuable for decision maker in determining order and capacity of devices which gaining a voltage stabilization. As a result, the objectives of voltage stabilization and cost minimization were achieved simultaneously. This realizes the economic efficiency of the system. We start by showing how to solve systems of linear equations using the language of pivots and tableaus. The effectiveness of this technique is demonstrated in modified PSS/E MIGUM 45 bus system. The simulation results show the effectiveness of this algorithm by comparing the outcome withseveral established methods.

      • KCI등재

        영어 독해 문제 난이도와 학습자 수준에 따른 고등학생들의 상위인지 전략 사용에 관한 연구

        안창용(Ahn, Chang-yong),한문섭(Han, Moon-sub) 학습자중심교과교육학회 2016 학습자중심교과교육연구 Vol.16 No.5

        본 연구의 목적은 읽기 능력이 다른 고등학생들이 난이도가 다른 영어 독해 문제에 대해 어떠한 독해 전략을 사용하는지에 대한 양상을 알아보고 그 결과를 토대로 학생의 읽기 능력에 따라, 문제의 난이도에 따라 독해 전략에 대한 지도를 어떻게 해야 할지 제시하는 것이다. 본 연구는 읽기 능력이 다른 고등학교 학생들이 난이도가 다른 독해 문제를 해결할 때 사용한 상위인지 전략을 측정하기 위해 설문조사를 하였다. 설문지는 Mokhtari와 Reichard(2002)의 MARSI(Metacognitive Awareness of Reading Strategies Inventory)의 항목 중에서 시험 상황에 적절하지 않은 항목들을 제외하고 나머지 항목들을 우리말로 번역하여 제공하였으며 모의고사 성적에 따라 상, 중, 하위 집단으로 분류된 학생들이 난이도가 다른 문제를 해결할 때 어떠한 전략을 사용하는지 대답을 하도록 설문지를 구성하였다. 그 결과, 첫째, 읽기 능력이 우수한 학습자일수록 총체적 독해 전략(GLOB), 문제 해결 전략(PROB), 지원적 독 해 전략(SUP) 세 가지 모든 영역의 상위인지 전략을 많이 사용하고 있다. 둘째, 문제의 난이도가 높을수록 학생들은 더 많은 상위인지 전략을 사용하고 문제의 난이도에 따라 학습자들이 활용하는 상위인지 전략의 종류가 다르다. 셋째, 문제의 난이도에 따라 상, 중, 하위 집단 간에 활용하는 상위인지 전략의 종류가 다르다. 따라서, 중위 집단 학생들이 상위 집단으로, 하위 집단 학생들이 중위 집단으로 향상하기 위해서는 그에 알맞은 방법을 안내해야 할 것이다. The purpose of this study is to investigate the use of meta-cognitive strategies of Korean high school students depending on their reading proficiency and the degree of difficulty of reading passages and to provide guidance about how to teach reading strategies. The study conducted survey about students meta-cognitive reading strategy uses by adapting MARSI(Mokhtari & Reichard, 2002). After grouping students into three group (high, middle, low proficiency group) by the result of reading test, each student was asked to answer the survey questions about how they use meta-cognitive reading strategies in solving reading questions. The results of this study are as follows. First, students in high proficiency group more frequently use reading strategies in all categories of meta-cognitive strategies: Global Reading Strategies, Problem-Solving Strategies and Support Reading Strategies. Second, the more difficult the reading passages are, the more frequently students use meta-cognitive reading strategies. However, if the reading passages are too difficult for students, the use of meta-cognitive reading strategies is reduced. Third, students who have different reading proficiency use different items of meta-cognitive reading strategies. To guide middle or low proficiency level students to become more proficient readers, teachers should offer appropriate items of meta-cognitive reading strategies to students depending on their reading proficiency. Though, meta-cognitive strategy use in reading is a crucial part of learning English, students can not use meta-cognitive reading strategies when their reading ability is not good enough for difficult passages. Therefore, it is recommended that teachers instruct students to improve their reading skills as well as to explore appropriate meta-cognitive reading strategies.

      • KCI등재

        실시간 전력 계통 해석을 위한 InTouch HMI 구현

        안창한(Chang-Han Ahn),이상덕(Sang-Deok Lee),박지호(Ji-Ho Park),장병훈(Byung-Hoon Chang),이현철(Hyun-Chul Lee),이근준(Geun-Joon Lee),백영식(Young-Sik Baek) 대한전기학회 2009 전기학회논문지 Vol.58 No.12

        Uncertainty of power system operation increases due to complexity and facilities diversification in the power system. Therefore the importance of SCADA(Supervisory Control and Data Acquisition) system which obtain and manage the actual data in real-time is very important. Accordingly in the studies of power system analysis, the efforts to include real-time power system analysis in simulation and applications are made in many ways. The real-time communication characteristics of SCADA system is considered so as to develop the power system analysis program that matches actual system conditions. The observation and management of SCADA system is realized by Intouch which is mainly used for factory automation and PSS/E(Power System Simulator for Engineers) provides real time system data. SQL DB and Python language is used for real-time communication between the softwares. It is very comfortable to use the various functions in Intouch WindowMaker.

      • SCOPUSKCI등재

        셀로판필름包裝이 半鹽乾고등어의 加工 및 貯藏中의 品質에 미치는 效果

        안창범(Chang-Bum Ahn),김복규(Bok-Gyu Kim),이채한(Chae-Han Lee),이호연(Ho-Yeon Lee),이응호(Eung-Ho Lee) 한국식품영양과학회 1991 한국식품영양과학회지 Vol.20 No.2

        반염건(半鹽乾)고등어 제조시 염지(鹽漬)처리 후 건조하는 공정에서 값싼 셀로판필름으로 포장하여 건조함으로써 제품의 제조 및 저장중 품질에 미치는 효과에 대해 실험하였다.<br/> 제조 직후 제품(C)와 (P)의 수분함량은 각각 56.2%, 63.6%로 (P)의 수분함량이 7.4%높았다. pH, 휘발성염기질소 및 아미노질소의 저장중 증가폭은 제품(P)가 적었다. 색조(L값, a값, b값)는 저장중 제품(C), (P) 모두 감소하는 경향이었다. 생균수는 저장초기에 약간 감소하다가 그 이후로 계속 증가하여 제품(C)는 14일째에 8.5×10^5/g 이었으나 제품(P)는 저장 21일째에도 3.0×10^5/g이었다. TMAO는 저장중 감소하는 TMA는 증가하는 경향이었고 그 증감의 폭은 제품(P)가 적었다. TMA값과 과산화물값은 저장중 증가하다가 저장 14일 이후로 감소하였고 증가폭은 제품(P)가 적었다. 혼합지방산에 있어서 폴리엔산의 저장중 감소율 역시 제품(P)가 적었다. 관능 검사결과 저장 14일째에는 제품(C)는 (P)에 비해 현저히 품질이 떨어졌고 제품(P)는 저장 14일째에도 식용가능하였다. 이화학적 및 관능적평가로 미루어 보아 셀로판필름으로 포장한 후 건조하여 만든 반염건고등어 제품(P)는 포장하지 않고 제조한 제품(C)에 비해 품질유지면에서 우수하다는 결론을 얻었다. The preservative effect of cellophane film packing on the quality of semi-salted and dried mackerel was studied. The product(P) of semi-salted and dried mackerel was prepared from raw mackerel by filleting, cleaning, soaking in 15%(v/w) salt solution for 30min, draining, packing with cellophane film(PT# 300, thickness:20,㎛)and drying for 4 hrs at 40℃ in hot air dryer. The product (C) was also prepared without cellophane film packing after draining. The product (C) and (P) were stored at 5.0±0.5℃. After processing and during storage, moisture content of product (P) was higher than that of product (C), but contents of VBN(volatile basic nitrogen), amino nitrogen and TMA of product(P) on dry basis were lower than those of product (C). Viable cell count, TBA value, peroxide value and decreasing rate of polyenoic acid of product (p) were also lower than those of product (C). In sensory evaluation, the shelf life of product (C) was about 9 days and that of product (P) was about 14 days. From the results of chemical and sensory evaluation, it was concluded that cellophane film packing was a good condition for preserving the quality of semi-salted and dried mackerel.

      • KCI등재

        최적화 기법이 적용된 전력계통 안정화 시스템 개발

        안창한(Chang-Han Ahn),백영식(Young-Sik Baek) 대한전기학회 2015 전기학회논문지 Vol.64 No.3

        Various protective equiptments are used for the power system control and protection. Numerous facilities are monitored at the same time in real time and introduction of optimization method and analysis of the method are required for generation control and facility management considering the demand fluctuations. However, the existing system analysis programs are difficult to link with the other sw and there are some problems with user convenience. To solve these problems the present conditions of the system are figured out in real time and the equipment insert method was estimated by optimization method, and the system that showed the system analysis program is developed. PSS/E has been used as system anlysis program for stabilizing system development which applied the optimization. method and Python language is applied in order to link the input and output values with the DB automatically. Lastly, DLL of matlab has been made included in C++ for solving the objective function using opmization method.By linking this to DB, power flow was calculated in PSS/E and the result was represented by Intouch screen.

      • KCI등재

        확장 JPEG 표준을 이용한 점진식 의료 영상 압축

        안창,한상우,김일연,Ahn, Chang-Beom,Han, Sang-Woo,Kim, Il-Yeon 대한의용생체공학회 1994 의공학회지 Vol.15 No.2

        The international standard for digital compression and coding of continuous-tone still image known as JPEG (Joint Photographic Experts Group) standard is investigated for medical image archiving and communication. The JPEG standard has widely been accepted in the areas of electronic image communication, computer graphics, and multimedia applications, however, due to the lossy character of the JPEG compression its application to the field of medical imaging has been limited. In this paper, the JPEG standard is investigated for medical image compression with a series of head sections of magnetic resonance (MR) images (256 and 4096 graylevels, $256 {\times}256$size). Two types of Huffman codes are employed, i. e., one is optimized to the image statistics to be encoded and the other is a predetermined code, and their coding efficiencies are examined. From experiments, compression ratios of higher than 15 were obtained for the MR images without noticeable distortion. Error signal in the reconstructed images by the JPEG standard appears close to random noise. Compared to existing full-frame bit-allocation technique used for radiological image compression, the JPEG standard achieves higher compression with less Gibb's artifact. Feature of the progressive image build-up of the JPEG progressive coding may be useful in remote diognosis when data is transmitted through slow public communication channel.

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