• 제목/요약/키워드: An Chung Hwan

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Digital Image Quality Assessment Based on Standard Normal Deviation

  • Park, Hyung-Ju;Har, Dong-Hwan
    • International Journal of Contents
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    • 제11권2호
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    • pp.20-30
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    • 2015
  • We propose a new method that specifies objective image quality factors by evaluating an image quality measurement model using random images. In other words, No-Reference variables are used to evaluate the quality of an original image without using any reference for comparison. 1000 portrait images were collected from a web gallery with votes constituting over 30 recommendation values. The bottom-up data collecting process was used to calculate the following image quality factors: total range, average, standard deviation, normalized distribution, z-score, preference percentage. A final grade is awarded out of 100 points, and this method ranks and grades the final estimated image quality preference in terms of total image quality factors. The results of the proposed image quality evaluation model consist of the specific dynamic range, skin tone R, G, B, L, A, B, and RSC contrast. We can present the total for the expected preference points as the average of the objective image qualities. Our proposed image quality evaluation model can measure the preferences for an actual image using a statistical analysis. The results indicate that this is a practical image quality measurement model that can extract a subject's preferred image quality.

이중 대역 개구면 결합 공진기 급전 마이크로스트립 안테나 설계 (Dual Band Design of Aperture-Coupled Cavity-Fed Microstrip Antenna)

  • 장국현;남경민;이장환;남상호;김철언;김정필
    • 대한전자공학회논문지TC
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    • 제44권3호
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    • pp.26-32
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    • 2007
  • 개구면 결합 공진기 급전 마이크로스트립 패치 안테나의 단순하고도 정확한 등가 회로를 추출한다. 이 등가회로는 이상적인 트랜스포머, 어드미턴스 소자, 그리고 전송선으로 구성되고 각 소자 값들은 가역 정리와 스펙트럼 영역 이미턴스 방법에 기반한 복소 전력 개념으로부터 구할 수 있다. 기 게재된 논문의 연구 결과를 이용하여 제안한 등가회로의 타당성을 검증한 후 이중 대역 안테나를 유전 알고리즘과 Holder-Mead 방법을 통한 이종 진화적 최적화 방법으로 설계하였다. 설계 목표치에 적합한 결과를 도출하였고, 이 결과는 이종 진화적 최적화 방법이 설계에 매우 효율직임을 확인해 준다.

Syntheses of Cu2SnSe3 and Their Transformation into Cu2ZnSnSe4 Nanoparticles with Tunable Band Gap under Multibubble Sonoluminescence Conditions

  • Park, Jongpil;Lee, Won Young;Hwang, Cha Hwan;Kim, Hanggeun;Kim, Youngkwon;Shim, Il-Wun
    • Bulletin of the Korean Chemical Society
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    • 제35권8호
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    • pp.2331-2334
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    • 2014
  • $Cu_2SnSe_3$ (CTSe) and $Cu_2ZnSnSe_4$ (CZTSe) nanoparticles were synthesized by sonochemical reactions under multibubble sonoluminescence (MBSL) conditions. First, $Cu_2SnSe_3$ nanoparticles were synthesized by the sonochemical method with an 85% yield, using CuCl, $SnCl_2$, and Se. Second, ZnSe was coated on the CTSe nanoparticles by the same method. Then, they were transformed into CZTSe nanoparticles of 5-7 nm diameters by heating them at $500^{\circ}C$ for 1 h. The ratios between Zn and Sn could be controlled from 1 to 3.75 by adjusting the relative concentrations of CTSe and ZnSe. With relatively lower Zn:Sn ratios (0.75-1.26), there are mostly CZTSe nanoparticles but they are believed to include very small amount of CTS and ZnSe particles. The prepared nanoparticles show different band gaps from 1.36 to 1.47 eV depending on the Zn/Sn ratios. In this sonochemical method without using any toxic or high temperature solvents, the specific stoichiometric element Zn/Sn ratios in CZTSe were controllable on demand and their experimental results were always reproducible in separate syntheses. The CZTSe nanoparticles were investigated by using X-ray diffractometer, a UV-Vis spectrophotometer, scanning electron microscope, Raman spectroscopy, and a high resolution-transmission electron microscope.

허혈후 칼슘 결핍 용액의 재관류가 적출 관류 기니픽 심근 세포에 미치는 영향에 관한 전자현미경적 관찰 (An Electron Microscopic Study on the Effect of Calcium-free Reperfusion in Isolated Perfused Guinea Pig Heart after Global Ischemia)

  • 오승환;김호덕;라봉진
    • Applied Microscopy
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    • 제20권1호
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    • pp.65-76
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    • 1990
  • The effect of calcium-free reperfusion for 5, 10, and 15 minutes, respectively, followed by continuous reperfusion with normal Tyrode solution containing 1.0mM calcium chloride, after global ischemia in the isolated perfused guinea pig heart by Langendorff techniques was examined with transmission electron microscope. Compared to the nomal Tyrode solution-perfused control hearts, the 5 minute calcium-free-reperfused hearts showed loss or thickening of Z lines, focal sarcolemmal disruption, mitochondrial swelling, clumping of chroma-tin, intracellular fluid accumulation, and some separation of cell junctions, especially the fasciae adherentes. These changes became more severe in the hearts of 10 minute calcium-free reperfusion. Subsarcolemmal larger bleb and near complete separation of cell junctions were noticed. In the 15 minute calcium-free-reperfused hearts, irreversible ultrastructural changes including contraction bands, biazrre mitochondria, and sarcolemmal destruction were widely distributed. The severity of myocardial changes were in accordance with the duration of calcium-free reperfusion. These changes indicate that calcium-free reperfusion regardless of its duration could not salvage the post-ischemic myocardium probably due to development of calcium paradox.

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Ecological characteristics of areas naturally inhabited by Dolbae trees(Pyrus pyrifolia) on Mt. Kaya

  • Ahn, Young-Hee;Chung, Kyu-Hwan
    • 한국환경과학회지
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    • 제11권11호
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    • pp.1149-1156
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    • 2002
  • The ecological characteristics of Dolbae trees, a valuable genetic resource for native pyrus fruit trees, were investigated at four naturally inhabited areas on Mount Kaya, Gyeongsangnam-Do. Most Dolbae trees were found on the southwest side of an old hiking path to a mountain valley at altitudes of 610∼670 m. The surrounding flora consisted of 46 families, 69 genera, 75 species, and 10 varieties. The natural habitat of the Dolbae trees was basically a deciduous broad-leaved forest with a predominance of Quercus serrata and ligneous plants(xylophytes) from the Fagaceae and Betulaceae families. The habitat was also found to be in a second transition resulting from forest disturbance and exhibited a degree of diversity of 2.901-5.065, based on Shannon-Weiner's index. Examination of the Dolbae trees found in Mount Kaya revealed diameter breast heights(DBHs) ranging from 10 to 60 cm, including six old and large Dolbae trees with a DBH of 50∼60 cm, which will be particularly valuable as a genetic resource. Accordingly, the current results suggest that the study areas are a secondary forest in a typical mid-temperate zone resulting from forest damage about 10 years earlier.

Development and Application of Failure-Based Learning Conceptual Model for Construction Education

  • Lee, Do-Yeop;Yoon, Cheol-Hwan;Park, Chan-Sik
    • Journal of Construction Engineering and Project Management
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    • 제1권2호
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    • pp.11-17
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    • 2011
  • Recent demands from construction industry have emphasized the capability for graduates to have improved skills both technical and non-technical such as problem solving, interpersonal communication. To satisfy these demands, problem-based learning that is an instructional method characterized by the use of real world problem has been adopted and has proven its effectiveness various disciplines. However, in spite of the importance of field senses and dealing with real problem, construction engineering education has generally focused on traditional lecture-oriented course. In order to improve limitations of current construction education and to satisfy recent demands from construction industry, this paper proposes a new educational approach that is Failure-Based Learning for using combination of the procedural characteristics of the problem-based learning theory in construction technology education utilizing failure information that has the educational value in the construction area by reinterpreting characteristics of construction industry and construction failure information. The major results of this study are summarized as follows. 1) Educational effect of problem-based learning methodology and limitation of application in construction area 2) The educational value of the information on construction failure and limitation in application of the information in construction sector 3) Anticipated effect from application of the failure-based learning 4) Development and application of the failure-based learning conceptual model.

핀 봉다발의 압력강하 특성 연구 (An Investigation of Pressure Drop Characteristics of Finned Rod Bundles)

  • Chung, Moo-Ki;Chung, Chang-Hwan;Chung, Heung-June;Song, Chul-Hwa;Yang, Sun-Kyu
    • Nuclear Engineering and Technology
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    • 제23권3호
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    • pp.328-339
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    • 1991
  • 30 MW 열출력을 갖는 다목적 연구용 원자로(KMRR)가 원자력연구소에선 개발되고 있다. 열수력 연구의 일환으로 길이 방향으로 핀이 달린 연료봉다발의 압력강하특성을 실험으로 연구하였다. 본 논문에서는 넓은 유량범위에서 적용할 수 있는 핀 연료봉다발에서의 압력강하 상관식의 도출과 압력강하에 미치는 핀 영향의 조사에 중점을 두었다. 도출된 KMRR 핵연료봉다발의 마찰계수 상관식을 원형관의 실험결과와 비교하였을 때 저유량 실험영역에서는 충류시의 해석값인 64/Re 보다 큰 값을 가졌으나 Re가 증가되면 Blasius 상관식보다 낮아지는 경향을 나타내었다.

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알츠하이머 치매 의심 환자의 행동심리증상에 대한 복합한의치료 1례: 증례 보고 (Application of Complex Korean Medicine Therapy to a Patient with Behavioral and Psychological Symptoms of Dementia from Suspected Alzheimer's Disease: Case Report)

  • 임혁빈;조희근;김종환
    • 동의신경정신과학회지
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    • 제30권3호
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    • pp.287-293
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    • 2019
  • Objectives: The purpose of this study was to report the clinical effectiveness of the complex Korean medicine therapy on a patient with BPSD (Behavioral and Psychological Symptoms of Dementia) due to suspected Alzheimer's disease. Methods: We experienced an age 73 female who complained of a depressive mood, insomnia, and accompanying symptoms such as abnormal behavior. During treatment, the patient received acupuncture and herbal medicine. The clinical effects were evaluated through KGDS (Korean Form of Geriatric Depression Scale) and subjective statements of the patient. Results: After the complex Korean medicine therapy, the treatments ameliorated overall symptoms that the patient complained about. The patient was more positive and slept better after the treatment. No specificities or adverse effects were reported during treatment. Conclusions: This study suggests the possibility of treating patients with BPSD with complex Korean medicine therapy.

Application of two different similarity laws for the RVACS design

  • Min Ho Lee;Ji Hwan Hwang;Ki Hyun Choi;Dong Wook Jerng;In Cheol Bang
    • Nuclear Engineering and Technology
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    • 제54권12호
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    • pp.4759-4775
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    • 2022
  • The RVACS is a versatile and robust safety system driven by two natural circulations: in-vessel coolant and ex-vessel air. To observe interaction between the two natural circulations, SINCRO-IT facility was designed with two different similarity laws simultaneously. Bo' based similarity law was employed for the in-vessel, while Ishii's similarity law for the ex-vessel excluding the radiation. Compared to the prototype, the sodium and air system, SINCRO-IT was designed with Wood's metal and air, having 1:4 of the length reduction, and 1.68:1 of the time scale ratio. For the steady state, RV temperature limit was violated at 0.8% of the decay heat, while the sodium boiling was predicted at 1.3%. It showed good accordance with the system code, TRACE. For an arbitrary re-criticality scenario with RVACS solitary operation, sodium boiling was predicted at 25,100 s after power increase from 1.0 to 2.0%, while the system code showed 30,300. Maximum temperature discrepancy between the experiments and system code was 4.2%. The design and methodology were validated by the system code TRACE in terms of the convection, and simultaneously, the system code was validated against the simulating experiments SINCRO-IT. The validated RVACS model could be imported to further accident analysis.

DEVELOPMENT AND APPLICATION OF FAILURE-BASED LEARNING MODEL FOR CONSTRUCTION TECHNOLOGY EDUCATION

  • Do-Yeop Lee;Cheol-Hwan Yoon;Chan-Sik Park
    • 국제학술발표논문집
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    • The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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    • pp.99-106
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    • 2011
  • Recent demands from construction industry have emphasized the capability for graduates to have improved skills both technical and non-technical such as problem solving, interpersonal communication. To satisfy these demands, problem-based learning that is an instructional method characterized by the use of real world problem has been adopted and has proven its effectiveness various disciplines. However, in spite of the importance of field senses and dealing with real problem, construction engineering education has generally focused on traditional lecture-oriented course. In order to improve limitations of current construction education and to satisfy recent demands from construction industry, this paper proposes a new educational approach that is Failure-Based Learning for using combination of the procedural characteristics of the problem-based learning theory in construction technology education utilizing failure information that has the educational value in the construction area by reinterpreting characteristics of construction industry and construction failure information. The major results of this study are summarized as follows. 1) Educational effect of problem-based learning methodology and limitation of application in construction area 2) The educational value of the information on construction failure and limitation in application of the information in construction sector 3) Anticipated effect from application of the failure-based learning 4) Development and application of the failure-based learning model

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