• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.3
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• pp.243-255
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• 1990

The objective of this study is to present an efficient measurement method of the effective thermal diffusivity for the fibrous insulation material. The non-linear parameter estimation (NPE) method is adapted for this analysis because of its accuracy and its results are compared with those by other direct methods such as CTP, CHP and STD method. A experimental system is constructed with bell-jar vaccum chamber, diffusion pump, tube type furnace, control unit and data acquisition system included with A/D converter and IBM XT/AT personal computer. The typical results obtained from this study are as follows; 1) NPE method can be recommended as an useful and accurate method to measure the effective thermal diffusivity of insuation material because it is shown that the measurement error compared with those by other direct methods is reduced for standard material, NBS-1450b. 2) NPE method can minimize the effects of ill-measured temperature due to external disturbance, because the final value is found by point to point estimating. 3) NPE method dose not depend on the kinds of heat flux, since the surfac temperature are used to estimate the thermal diffusivity. 4) With NPE method, compared with the steady state method, a measuring time and a sample size could be reduced.

• KSBB Journal
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• v.4 no.3
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• pp.241-245
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• 1989

A carriersupported mycelial growth of Sreptomyces erythreus was applied to erythromycin fermentation sistem using celite as a support material. Hyphal growth through the pore matrices of the materials showed anchorages and provided a stable biofilm growth. When the phospate concentration was limited to 0.8g corn steep liquor/L(corresponding to 40mg KH2PO4/L), the specific production rate of erythromycin was increased from 557$\mu$g/g-cell.hr under unlimited condition to 2, 898 $\mu$g/g-cell.hr. A fluidized-bed bioreactor was operated for erythromycin production by a repeated fed-batch mode. The control of free mycelial concentration and the extension of production phase were considered important to maintain the reactor productivity at a desired level. The erythromycin production under phosphate-limited condition could be maintained for at least 600hrs.

• Korean Journal Plant Pathology
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• v.12 no.1
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• pp.91-98
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• 1996

벼도열병균 14개 균주와 벼 이외 화본과 식물 도열병균 12개 균주를 대상으로 rDNA의 ITS II 부위를 증폭하여 그들의 핵산 구조 차이를 분석함으로 도열병균 균주간 분류를 시도하였다. 5.8S rDNA의 3`-말단 부위와 28S rDNA의 5`-말단 부위의 sequence 중 5`-CCCGGGAATTCGCATCGATCGATCGAATGAAGA-ACGCAGC-3`와 5`-CCCGGGATCCTCCGCTTATT-GATATGC-3`를 이용하여 PCR 증폭을 하였을 때 벼도열병균 14개 균주는 동일한 길이의 단일 밴드를 형성하였으며 벼 이외 화본과 식물 도열병균에서는 레드톱 식물로부터 분리한 도열병균만이 나머지 균주보다 38bp가 더 큰 길이를 가진 밴드를 형성하였다. PCR로 증폭된 DNA를 HaeIII와 MspI 제한효소로 절단하였을 때 벼도열병균 레이스간에는 제한효소 절단에 의한 전기영동 밴드 형태 차이를 관찰할 수 없었으나, 벼 이외 화본과 식물 도열병균 12개 균주는 3군으로 구분할 수 있었다. 벼도열병균 90=054와 강아지풀에서 분리한 도열병균 G90-5, 기장에서 분리한 G88-4, 바랭이에서 분리한 G88-5 그리고 레드톱에서 분리한 RT 균주의 ITS II 부위의 DNA 염기서열 비교 분석에 의하면 G88-4와는 다른 HaeIII와 MspI 제한효소 위치를 가지고 있었기에 제한효소 절단에 의한 전기영동 형태가 상이하였다. 또한 RT균주는 HaeIII와 MspI위치가 존재하지 않았다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.4
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• pp.89-101
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• 2015

In this study, it examined whether recognized career barriers among students of majoring in aviation affected career stress and career decision level, and career stress moderated the impact of career barriers on career decision level. For this purpose, it conducted a survey of aviation-related college students in C university from Sep. 21th. 2015 to Oct. 8th. 2015. A total of 225 questionnaires were analyzed using SPSS 21.0 statistical package program and frequency analysis, factor analysis, reliability analysis, regression analysis, and correlation analysis were conducted. Findings indicated that career barriers partly influenced the career stress and career decision level. Also, career stress had an negative effect on career decision level. Lastly, career stress moderated the impact of career barriers on career decision level. The implication of this paper would be used as a fundamental material to guide for career direction to students majoring in aviation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.4
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• pp.561-571
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• 1997

In this paper, the fundamental equations are developed for the pulsatile laminar flow generated by changing the oscillatory flow with $0{\leq}f{\leq}48Hz$ into a steady one with $0{\leq}Re{\leq}2500$ in a rigid circular pipe. Analytical solutions for the wave propagation factor k, the axial distributions of cross-sectional mean velocity $u_m$ and pressure p are schematically derived and confirmed experimentally. The axial distributions of centerline velocity and pressure were measured by using Pitot-static tubes and strain gauge type pressure transducers, respectively. The cross-sectional mean velocity was calculated from the centerline velocity by applying the parabolic distribution of the laminar flow and it was confirmed by using the ultrasonic flowmeter. It was found that the axial distributions of cross-sectional mean velocity and pressure agree well with theoretical ones and depend only on the Reynolds number Re and angular velocity $\omega$.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.11
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• pp.3041-3053
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• 1995

Cylindrical chokes are used widely as components of hydraulic equipments. The dynamic characteristics between flowrate and pressure drop through the cylindrical chokes were discussed by the frequency characteristics of the chokes. It was assumed no pressure recovery occurred near the downstream of the choke. The pulsating jetflow from the outlet of cylindrical chokes show very complex behaviours which are quite different from the steady jet flow but it's not clarified quantitatively. In order to utilize the chokes as a flowmeter, it is indispensable to discuss the estimation of the dynamics of pressure drop in the downstream jetflow region of cylindrical chokes. In this experimental study, it is clarified that the reattachment length depended on pressure wave is compared with it depended on velocity wave. A pulsating flow is verified by visualization method. In the present study, the flow characteristic variables of laminar pulsating flow are investigated analytically and experimentally in a circular pipe. Characteristic parameters of the ratios of inertia(.PHI.$_{t,1}$) and viscous(.PHI.$_{z,1}$) term to pressure term are introduced to describe the flow pattern of laminar pulsating flow. flow.low.

• Korean Journal of Breeding Science
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• v.43 no.5
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• pp.349-359
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• 2011

Agriculture plays a vital role in the sustenance of human society and is the fundamental of developing economies. Nitrogen is one of the most critical inputs that define crop productivity. To ensure better value for investment as well as to minimize the adverse impacts of the accumulative nitrogen species in environment, improving nitrogen use efficiency of crop plants is of key importance. Efforts have been made to study the genetic and molecular biological basis as well as the biochemical mechanisms involved in nitrogen uptake, assimilation, translocation and remobilization in crops and model plants. This review gives an overview of metabolic, enzymatic, genetic and biotechnological aspects of nitrogen uptake, assimilation, remobilization and regulation. This review presents the complexity of nitrogen use efficiency and the need for an integrated approach combining physiology, quantitative trait genetics, system biology, soil science, ecophysiology and biotechnological interventions to improve nitrogen use efficiency.

• Journal of Integrative Natural Science
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• v.15 no.1
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• pp.27-36
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• 2022

Metabus, currently represented by Second Life on the Internet, is the next-generation 3DCG Internet world in which the 2D Internet world has evolved, and has grown as a new ICT culture of mankind that can replace real society with virtual society. As such, the reason why the world of metabus has rapidly expanded is that the era of 3D Internet has arrived due to the evolution of the Internet, which only used information, and the spread of 5G communication in user-participating WEB. However, there are many situations in which laws do not exist in this virtual world and various illegal acts occur. As the Internet culture developed earlier, illegal activities by users began to appear, and as the legal responsibility of Internet providers was discussed, mankind quickly passed the Millennium Copyright Act or introduced new copyright protection measures such as technical protection, transmission rights, and rights management information. Therefore, this paper reviews and studies how to accept and further grow this new metabus culture, including the viewpoint of intellectual property.

• Journal of Integrative Natural Science
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• v.15 no.1
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• pp.37-48
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• 2022

Metabus, a three-dimensional virtual environment for digital communication, has gained a lot of attention recently. Even so, there are still many unanswered questions about the user's consciousness and behavior. A difference in nature from conventional digital communication is also unclear. This paper aims to study Metabus on a hypothetical premise by organizing the possibility of Metabus for communication activation based on a research project aimed at using Metabus to support the formation of a community of school dormitories and studio rental residents. After reviewing the establishment process and application cases of Metabus, we focus on the character (avatar) used as the user's alter ego within the metabus, which will allow customization of both form and content different from text-based communication. The "physicality" and the "spatiality" of the metaverse and the "immersion" they bring are among the most important, functional innovations. Based on this summary, a case of using metabuses will be reviewed to describe the research plan aimed at supporting community formation.

• KDI Journal of Economic Policy
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• v.19 no.1
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• pp.105-149
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• 1997

이 논문에서는 남북한 관계를 중심으로 분쟁해소와 협력관계 구축에 있어서 신뢰(信賴)가 할 수 있는 역할(役割)에 대해 검토해 보았다. 이 논문의 모델은 Kreps-Wilson(1982)의 신규진입 게임을 협력관계 구축이라는 새로운 상황에 맞게 변환시킨 순차적 게임모델로서 유한반복(有限反復) 게임구도와 비대칭적(非對稱的) 정보소유(情報所有)를 그 근간으로 한다. 북한이 남한정부가 진보적이라고 믿는 확률을 남한에 대한 '신뢰(信賴)'라고 정의할 때, 신뢰는 크게 나누어 다음과 같은 역할을 한다. 북한이 남한에 대해 작은 규모의 신뢰감만 가지고 있어도 피의자(被疑者)의 딜레마 (Prisoner's Dilemma) 상황을 피할 수 있으며 상당한 기간동안 남북협력관계(南北協力關係)가 지속될 수 있다. 왜냐하면 보수적 성향의 남한정부도 북한이 개혁정책을 추진할 때 대북(對北) 압박정책 대신 포용정책(包容政策)을 통해 얻을 수 있는 수익이 적지 않은 점을 고려하여 상당기간동안 포용정책을 선택할 동기가 있기 때문이다. 하지만 이와 같이 자신의 성향을 은폐하는 위장행동의 가능성이 높은 동안 신뢰(信賴)는 쉽게 증진되지 않는다. 다만 남북한이 협력을 통해 실질적인 수익을 얻을 수 있을 뿐이다. 남북협력관계를 구축하기 위해 남한이 할 수 있는 일은 정책대응에 소요되는 시간을 줄이는 한편, 개혁정책을 통해 북한이 얻을 수 있는 기대수익(期待收益)을 늘리고 남한에 배신당할 경우 입는 피해를 줄여주는 것이다. 특히 장기적인 관점에서 북한의 기대수익을 점진적으로 늘려 '신뢰도(信賴度)가 넘어야 할 문턱'을 낮추는 것이 효과적인 정책이다. 따라서 남북관계를 진전시키기 위해서는 북한의 지속적인 개혁을 조건으로 북한의 기대수익이 점진적으로 증가하는 KEDO식의 장기적 경협사업(經協事業)을 고안하여 추진해야 한다. 이에 반해 인도주의적 명분하에 일과성의 식량지원을 북한에 제공하는 것은 북한의 구조적(構造的) 경제난(經濟難) 해소나 남북관계의 지속적 진전에 별 도움이 안되는 정책이다. 북한은 북한 나름대로 남한을 한번 믿어볼 필요가 있다. 왜냐하면 상대방에 대한 불신(不信)은 결국 협력관계가 유지될 수 있는 기간을 감축시켜 비효율적인 결과를 초래하기 때문이다.