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A Study on the Oscillation Region and the Variation of Negative Resistance in Transistor Oscillators (트란지스터 발진기의 발진영역과 부저항의 변화에 관한 연구)

  • 이종각
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.8 no.3
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    • pp.15-26
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    • 1971
  • The paper presents a new method for analyzing oscillation regions of transistor oscillators. In transistor feedback oscillators oscillation region appears as a circle in feedback impedance complex plane. When the resistive component of feedback impedance is fixed and the reactive component of feedback impedance is varied or vice versa, the locus of maximum negative output conductance becomes hyperbola. In transistor crystal oscillators oscillation region is determined by two circles which make real part and imaginary part of input impedance zero in load impedance complex plane. When the resistive compoment of load impedance is fixed and the reactive colnponent of load impedance is varied or vice versa, the loci of maximum or minimum resistive component of input impedance become straight lines.

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Isolation of Actinomycetes Producing Extracellular Adenosin Deaminase (세포외 Adenosine Deaminase를 생산하는 방선균의 분리)

  • 전홍기;김태숙
    • Korean Journal of Microbiology
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    • v.28 no.1
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    • pp.83-89
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    • 1990
  • Two strains of actinomycetes producing extracellular adenosine deaminase, strain J-845S and strain J-326TK, were isolated from soil. Strain J-845S was gram-positive and non-acid-fast. This strain formed whitish, rod-shaped, smooth and non-motile spores on the aerial mycelium, and the spore chain was spiral. The hyphae of the mycelium branched abundantly. Cell wall chemotypes of the strain were of type I containing LL-diaminopimelic acids, and of phospholipid type II, and then strain J-845S was designated as Streptomyces sp.. Strain J-326TK was gram-positive and non-acid-fast. The hyphae of primary and aerial mycelium fragmented into irregular rod of coccus-like elements. The aerial mycelium either did not branch or sparsely branched. Cell wall composition was of type I and phospholipid type I. Thus, strain J-326TK was identified as Nocardioides sp.

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Rethinking Public Library Director's Duties : A Qualitative Approach (공공도서관장의 역할과 일상적 직무에 대한 질적 분석)

  • Chang, Duk-Hyun;Lee, Yeon-Ok;Yoon, Jin
    • Journal of Korean Library and Information Science Society
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    • v.34 no.4
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    • pp.253-270
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    • 2003
  • There are speculations toward public libraries in Korea including the destructive crisis in public libraries. As leaders in these organizations, the directors of public libraries need to be interested in the subject of leadership. Leadership is a major component of management of an organization in transition. The subject once was a sub-field prospered especially in 1970's and 1980's. Since then the perceptions of researchers and practitioners have changed due to new technologies. Recent literature in the field illustrates wide variety of concerns and issues of public library management. This paper attempts to highlight such issues and perceptions of the real world of libraries, portrayed through a qualitative analysis.

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Plane Surface Generation with a Flat End Mill (평 엔드밀을 이용한 평면가공에서의 가공면 형성기구)

  • Ryu, Si-Hyeong;Kim, Min-Tae;Choe, Deok-Gi;Ju, Jong-Nam
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.2 s.95
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    • pp.234-243
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    • 1999
  • Using the geometric and the vector methods, three dimensional surface texture and roughness models in flat end milling are developed. In these models, rear cutting effect on surface generation is considered along with tool run-out and tool setting error including tool tilting and eccentricity between tool center and spindle rotational center. Rear cutting is the secondary cutting of the already machined surface by the trailing cutting edge. The effects of tool geometry and tool deflection on surface roughness are also considered. For representing the surface texture more practically, three dimentional surface topography parameters such as RMS deviaiton, skewness and kurtosis are introduced and used in expressing the surface texture characteristics. Under various cutting conditions, it is confirmed that the developed models predict the real surface profile precisely. These models could contribute to the cutter design and cutting condition selection for the reduction of machining and manual finishing time.

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Three Cases of Primary Adenosquamous Carcinoma of Stomach (위에 발생한 원발성 선편평세포 암종 3례)

  • Choi, Joon-Hyuk;Kim, Mi-Jin;Nam, Hae-Joo;Choi, Won-Hee;Lee, Tae-Sook
    • Journal of Yeungnam Medical Science
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    • v.5 no.2
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    • pp.189-193
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    • 1988
  • Adenosquamous carcinoma of stomach is a mixed glandular-epidermoid tumor where both components are neoplastic. Its incidence is extremely rare. The five theories on the origin of squamous components are 1) island of ectopic squamous epithelium in the gastric mucosa, 2) squamous metaplasia of gastric epithelium, 3) squamous differentiation in a preexisting adenocarcinoma, 4) endothelial cell differentiated toward squamous elements, and 5) totipotential undifferentiated cells of the gastric mucosa. We experienced three cases of adenosquamous carcinoma. Case 1 was a 71-year-old female patient. ; an ulcerative lesion was present in the pylorus, measuring 5cm in diameter. Case 2 was a 57-year-old male patient. ; an ulcerative lesion is present in the pylorus, measuring 6 em in diameter. Case 3 was a 58-year-old female patient. ; an ulcerative lesion was present in the body and fundus, measuring 10cm in diameter. Microscopic examination revealed a mixed malignant squamous and adenomatous component.

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An Assembly Simulation of a Plane Block with Gravity and Welding Deformations (자중과 용접변형을 고려한 평블록 조립 시뮬레이션)

  • Jae-Gyou Roh;Jong-Gye Shin
    • Journal of the Society of Naval Architects of Korea
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    • v.36 no.3
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    • pp.122-133
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    • 1999
  • Overlap, excessive wide gaps, and errors between blocks during erection process increases cost and man-hour. In this paper, a system to simulate the assembly process is suggested and a plane block assembly of welding deformation with gravity is simulated in consideration of assembly order, deformations and errors occurring in the cutting and forming processes are not considered and welding deformations are acquired by equivalent stiffness and load method from experiments and hull double bottom plane block is assembled on a assembly order by panel method. It is certified that according to the order of assembly, intermediate product shape affects rigidity which affects welding deformations. Assembly order must be considered in the assembly process. It is certified that the gravity has important role in the assembly process.

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A Study on the Contents and Consumers' Recognition of Clothing Product Evaluation Statements in the Internet Apparel Shopping Mall (인터넷 쇼핑몰의 의류 상품평 내용과 소비자 인식에 관한 연구)

  • Choi Eun-Young
    • The Research Journal of the Costume Culture
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    • v.12 no.6 s.53
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    • pp.984-998
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    • 2004
  • The purpose of this study was to analyze contents of clothing product evaluation statements in the internet shopping mall and to discover consumers' recognition and evaluation of it. The data were collected from 151 consumers' statements in the four internet apparel shopping malls and a questionnaire was developed to measure consumers' recognition of clothing product evaluation statements. The questionnaire was administrated 272 consumers over 18 years old. The results of this study were as follows; First, The contents of clothing product evaluation statements in the internet shopping blog, were divided into three categories which were product, service and consumer buying decision process. Product category include evaluation of clothing product, description of difference between real product and product on the screen, and advice of uses. Service category include quickness and kindness in delivery, store preference for good service. For consumer buying decision process, motivation of purchasing, perceived risk, expression of satisfaction from good buying and canvassing for purchasing were included. Second, consumer recognized that clothing product evaluation statements has function of furnishing information, confirmation of purchasing decision, risk reduction of internet shopping, and interesting entertainment. Consumers also were dependent on product evaluation statements for making purchasing decision. And it was trusted by consumers. This recognition & evaluation were correlated with consumer's clothing product knowledge, involvement, risk perception of internet shopping, experiences of internet shopping. Managerial implications are provided for internet shopping mall.

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A Study on the Relation of the Service Factor of Appraisal Business and Customer Satisfaction (감정평가업에 있어서 서비스 요인과 고객만족의 관계에 대한 고찰)

  • Kim, Seung-Hyun;Min, Gu-Sik
    • The Journal of the Korea institute of electronic communication sciences
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    • v.7 no.3
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    • pp.649-660
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    • 2012
  • The future of appraisal industry looks negative in the reality of change of the property market and over-competition of the field. Unless Constituent members of appraisal industry cope actively with the changing circumstances the profit structure of their company will get worse and they will finally fall behind in the competition. The best policy to survive from the changing circumstances in the limited appraisal market is to provide better service and improve its structure in order to have differential competitiveness. The purpose of this study is to describe the relation between the service factors of appraisal industry and customer satisfaction for providing more effective and high quality appraisal service.

A study on the static seimic loads for the space structures of beam string structure (장현보구조형식을 가지는 공간구조물의 정적지진하중 평가법에 관한 연구)

  • Kim, Kwang-Il;Jung, Chan-Woo;Kang, Joo-Won
    • Proceeding of KASS Symposium
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    • 2008.05a
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    • pp.127-132
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    • 2008
  • Recent years, the response characteristics of large space structures have been studied. Then, for the large space structures with large rise-span ratio, it is clarified that the anti-symmetric mode are representatively amplified. That means the static seismic load for general ramen structure is not suitable for the space structure. In this paper, we propose static seismic loads for space structures and its concept. And for the space structures of beam string structures, execute the time history analysis and quasi static analysis and compare the results of them. From the results, we can prove the validity of static seismic load for space structure.

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