• 소음진동
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• 제6권2호
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• pp.163-177
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• 1996

An investigation on thermohydraulic stability of flow oscillations in the CANada Deuterium Uranium-600(CANDU-6) heat transport system has been conducted. Flow oscillations in reactor coolant loops, comprising two heat sources and two heat sinks in series, are possibly caused by the response of the pressure to extraction of fluid in two-phase region. This response consists of two contributions, one arising from mass and another from enthalpy change in the two-phase region. The system computer code used in the investigation os SOPHT, which is capable of simulating steady states as well as transients with varying boundary conditions. The model was derived by linearizing and solving one-dimensional, homogeneous single- and two-phase flow conservation equations. The mass, energy and momentum equations with boundary conditions are set up throughout the system in matrix form based on a node-link structure. Loop stability was studied under full power conditions with interconnecting the two compressible two phase regions in the figure-of-eight circuit. The dominant function of the interconnecting pipe is the transfer of mass between the two-phase regions. Parametric survey of loop stability characteristics, i. e., damping ratio and period, has been made as a function of geometrical parameters of the interconnection line such as diameter, length, height and orifice flow coefficient. The stability characteristics with interconnection line has been clarified to provide a simple criterion to be used as a guide in scaling of the pipe.

• 한국수산과학회지
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• 제33권6호
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• pp.565-571
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• 2000

기존의 Cx 배열을 참고로 종내${cdot}$종간을 통하여 잘 보존되어져 있는 영역에서 primer를 설계하고, 은어의 난소를 재료로 하여 PCR을 실시하였다. 증폭된 cDNA 단편을 이용하여, 5'RACE 및 3'RACE법에 의해 미지의 영역을 cloning하여 난소에서 발현하는 Cx cDNA의 전염기배열을 결정하였다. 기존의 Cx 배열과 상동성을 비교한 결과, 대서양산 민어의 Cx32.7과 $63.8{\%}$, bovine의 Cx44와 $61.6{\%}$ 및 대서양산 민어의 Cx32.2와는 $56.7{\%}$의 상동성이 나타났다. 본 cDNA는 35,028 Da의 분자량을 code하는 open reading frame (ORF)으로 구성되어 있어, 은어 Cx35로 명명되었다. 또한 아미노산 배열의 친수성${\cdot}$소수성 영역의 분포예측 결과, 4곳의 소수성 영역과 4곳의 친수성 영역을 교차하는 전형적인 Cx의 구조와 일치하였으며, Cx family의 공통${\cdot}$필수적인 배열인 제1세포외 domain의 consensus 배열 및 제2세포외 domain의 consensus 배열도 존재하였다.

• 인지과학
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• 제17권1호
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• pp.15-27
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• 2006

한국어 단어의 글자 수, 받침의 수와 위치, 합성어 여부가 기억폭에 미치는 효과를 검증하였다. 그 결과, 전반적으로 글자가 많은 단어일수록 기억폭이 작았으며, 두 글자 단어들에서 받침이 많을수록 기억폭이 더 작았고(기억폭에 대한 받침효과), 합성어보다 단일어의 기억폭이 더 컸다. 단어당 읽기 속도를 측정한 결과, 글자가 많은 단어일수록 속도가 느렸지만, 두 글자 단어들에서 뒷받침단어의 읽기 속도가 받침없는 단어, 앞받침단어 및 양받침단어보다 더 빨랐고(읽기 속도에 대한 말미 받침효과), 합성어보다 단일어의 읽기 속도가 더 빨랐다. 기억폭과 읽기 속도간에 관찰된 이러한 관계는 단어길이효과에 대한 음운루프설명과 잘 부합되지 않으며, 기억폭이 음운정보 뿐만 아니라 시각적 캐시에 표상되는 철자 정보의 영향을 받는다는 설명을 지지해준다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.189-194
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• 2005

The evaporation heat transfer and pressure drop of $CO_2$ in a small diameter tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator(test section). The test section was made of a horizontal stainless steel tube with the inner diameter of 4.57 mm, and length of 4 m. The experiments were conducted at mass flux of 200 to 700 $kg/m^2s$, saturation temperature of $0^{\circ}C$ to $20^{\circ}C$, and heat flux of 10 to 20 $kW/m^2$ . The test results showed the evaporation heat transfer of $CO_2$ has great effect on more nucleate boiling than convective boiling. The evaporation heat transfer coefficients of $CO_2$ are highly dependent on the vapor quality, heat flux and saturation temperature. The evaporation pressure drop of C02 are highly dependent on the mass flux. In comparison with test results and existing correlations, correlations failed to predict the evaporation heat transfer coefficient and pressure drop of $CO_2$, therefore, it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient and friction pressure drop of $CO_2$ in a horizontal tube.

• 한국항공우주학회지
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• 제31권3호
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• pp.39-49
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• 2003

본 논문에서는 먼저 델타연산자 접근법과 섭동기법을 소개하였다. 전자는 수치연산에 있어서 round-off error를 줄여주고 후자는 시스템을 빠른 종속시스템과 느린 종속시스템으로 분리하여 연산시간을 줄여준다. 항공기의 동력학은 종방향 혹은 횡방향 모두 장주기(Phugoid)와 단주기 운동을 동시에 보여준다. 여기서는 경비행기 Beaver의 횡방향 모델에 섬동기법과 델타접슨법을 적용하여 얻는 근사치 해를 정확한 해와 비교하였다. 그 겨로가 개루프 시스템의 경우는 단 한번의 iteration을 시행하여 얻은 근사치 해가 정확한 해와 일치했고, 페루프 시스템의 경우는 iteration없이도 근사치 값이 정확한 해와 일치하였다. 이로써 제안된 방법들의 적용이 항공기 동력학 및 제어에 있어서 매우 유효함이 검증되었다.

• Molecules and Cells
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• 제23권2호
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• pp.228-238
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• 2007

Since molecular structure of hnRNP is not available in foreseeable future, it is best to construct a working model for hnRNP structure. A geometric problem, assembly of $700{\pm}20$ nucleotides with 48 proteins, is visualized by a frame work in which all the proteins participate in primary binding, followed by secondary, tertiary and quaternary binding with neighboring proteins without additional import. Thus, 40S hnRNP contains crown-like secondary structure (48 stemloops) and appearance of 6 petal (octamers) rose-like architectures. The proteins are wrapped by RNA. Co-transcriptional folding for RNP fibril of FMR1 gene can produce 2,571 stem-loops with frequency of 1 stem-loop/15.3 nucleotides and 53 40S hnRNP beaded structure. By spliceosome driven reactions, there occurs removal of 16 separate lariated RNPs, joining 17 separate beaded exonic structures and anchoring EJC on each exon junction. Skipping exon 12 has 5'GU, 3'AG and very compact folding pattern with frequency of 1 stem-loop per 12 nucleotides in short exon length (63 nucleotides). 5' end of exon 12 contains SS (Splicing Silencer) element of UAGGU. In exons 10, 15 and 17 where both regular and alternative splice sites exist, SS (hnRNP A1 binding site) is observed at the regular splicing site. End products are mature FMR-1 mRNP, 4 species of Pri-microRNAs derived from introns 7,9,15 and 3'UTR of exon17, respectively. There may also be some other regulatory RNAs containing ALU/Line elements as well.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.262-267
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• 2005

The evaporation heat transfer coefficient of $CO_2$ in a horizontal round tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator(test section). The test section was made of a horizontal stainless steel tube with the inner diameter of 7.75 mm, and length of 5 m. The experiments were conducted at mass flux of 200 to 500 $kg/m^2s$, saturation temperature of $-5^{\circ}C$ to $5^{\circ}C$, and heat flux of 10 to 40 $kW/m^2$. The test results showed the evaporation heat transfer of $CO_2$ has great effect on more nucleate boiling than convective boiling. The evaporation heat transfer coefficients of $CO_2$ are highly dependent on the vapor quality, heat flux and saturation temperature. In comparison with teat results and existing correlations, correlations failed to predict the evaporation heat transfer coefficient of $CO_2$, therefore, it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient of $CO_2$ in a horizontal tube.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.353-358
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• 2005

The heat transfer and pressure drop of supercritical $CO_2$ cooled in a helically coiled tube was investigated experimentally. The experiments were conducted without oil in the refrigerant loop. The experimental apparatus of the refrigerant loop consist of receiver, a variable speed pump, a mass flowmeter, a pre-heater, a gas cooler(test section) and an isothermal tank. The test section is a helically coiled tube in tube counter flow heat exchanger with $CO_2$ flowed inside the inner tube and coolant( water) flowed along the outside annular passage, It was made of it copper tube with the inner diameter of 4.55[mm]. the outer diameter of 6.35 [mm] and length of 10000 [mm]. The refrigerant mass fluxes were $200^{\sim}600$ [kg/m2s] and the inlet pressure of gas cooler varied from 7.5 [MPa] to 10.0 [MPa]. The main results are summarized as follows : The heat transfer coefficient of supercritical $CO_2$ increases, as the cooling pressure of gas cooler decreases. And the heat transfer coefficient increases with the increase of the refrigerant mass flux. The pressure drop decreases in increase of the gas cooler pressure and increases with increase the refrigerant mass flux.

• Archives of Pharmacal Research
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• 제29권1호
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• pp.88-95
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• 2006

Analysis of molecular nature of mitochondrial DNA (mtDNA) could be powerful marker for anthropological studies of modern populations. While population genetic studies on mtDNA have been reported for several ethnic groups, no such study has been documented for the Korean population. We surveyed mtDNA polymorphisms in the HVS I of noncoding D-loop region and its upstream region from 430 unrelated healthy Korean population by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequencing analysis. PCR product with 2,790 bp spanning the specific mtDNA region (mt13715-16504) was subjected to RFLP analysis using 6 restriction enzyme (Hinf I, Hae III, Alu I, Dde I, Mbo I, Rsa I). On the PAUP analysis of PCR-RFLP results, 38 mtDNA haplotypes (Hap 1-38) were detected in the Korean populations, which were classified into 11 haplogroups (Grp 1-11) of related haplotypes encompassing all 38 haplotypes. In comparison of sequencing data with Anderson's reference sequence, the transition type was more prevalent than the transversion type. Insertions or deletions were not found. In addition, three of the polymorphic sites (A16240C, A16351G, G16384A) in HVS-I region are determined newly. The polymorphic sites were distributed randomly in the region, though the frequency at each site was variable. Thus, this research might be required for the genealogical study of Orientals.

• 한국가스학회지
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• 제22권1호
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• pp.45-52
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• 2018

이 논문에서는 도시가스 배관 중 교량에 설치된 배관 398개소에 대해 현황을 조사하고, 배관을 설치연도별, 길이별, 원격차단장치 설치여부 등 특성별로 분류하여 분석하였다. 분석결과 20년 이상 장기사용배관이 43.0%를 차지하고 있었고, 원격차단장치 미설치 교량배관은 89.4%에 달하는 등 드러난 현상에 대한 안전관리 방안을 제시하였다. 또한 조사된 교량설치 배관 중 76개소를 선정한 후 응력해석 전용프로그램인 CAESAR-II를 이용하여 응력특성을 연구하고, 교량배관 중 루프관을 설치할 경우 루프관의 위치 및 크기가 배관의 합성응력에 미치는 영향을 분석하였다. 본 연구의 결과를 통해 교량 배관의 설치, 검사 및 진단 기준 개선 등에 활용하여 교량설치 배관에 대한 안전성 향상에 도움이 될 수 있을 것으로 판단한다.