• 소성∙가공
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• 제16권7호
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• pp.530-537
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• 2007

This paper is concerned with the analysis of plastic deformation of bimetal co-extrusion process. Two sets of material combination have been adopted for analysis, i.e. combinations of Cu/Al and Fe/Al. In the first set of material combination, the selected materials are AA 1100 aluminum alloy as hard material and CDA 110 as soft one. This type of material selection is to examine the effect of hard core and soft sleeve and vice versa on the deformation pattern in terms of plastic zone and velocity discontinuity along the contact surface between construction materials. Four different cases of co-extrusion process in terms of material combination and interference bonding were simulated to investigate the effect of material arrangement between core and sleeve, and of bonding on the plastic zones and velocity discontinuity. In the other set of material combination, model materials used as core and sleeve were AA 1100 and AISI 1010, which are relatively soft and hard, respectively. Process parameters except diameter ratio of core to sleeve material such as semi-die angle, reduction in area in global sense and die comer radius have been set constant throughout the simulation to concentrate our effort on the analysis of influence of diameter ratio on deformation behavior such as deformation zone, surface expansion, exit velocity discontinuity between composite materials, and extrusion forces.

• Nuclear Engineering and Technology
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• 제44권7호
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• pp.727-734
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• 2012

A new advanced safety feature of DVI+ (Direct Vessel Injection Plus) for the APR+ (Advanced Power Reactor Plus), to mitigate the ECC (Emergency Core Cooling) bypass fraction and to prevent switching an ECC outlet to a break flow inlet during a DVI line break, is presented for an advanced DVI system. In the current DVI system, the ECC water injected into the downcomer is easily shifted to the broken cold leg by a high steam cross flow which comes from the intact cold legs during the late reflood phase of a LBLOCA (Large Break Loss Of Coolant Accident)For the new DVI+ system, an ECBD (Emergency Core Barrel Duct) is installed on the outside of a core barrel cylinder. The ECBD has a gap (From the core barrel wall to the ECBD inner wall to the radial direction) of 3/25~7/25 of the downcomer annulus gap. The DVI nozzle and the ECBD are only connected by the ECC water jet, which is called a hydrodynamic water bridge, during the ECC injection period. Otherwise these two components are disconnected from each other without any pipes inside the downcomer. The ECBD is an ECC downward isolation flow sub-channel which protects the ECC water from the high speed steam crossflow in the downcomer annulus during a LOCA event. The injected ECC water flows downward into the lower downcomer through the ECBD without a strong entrainment to a steam cross flow. The outer downcomer annulus of the ECBD is the major steam flow zone coming from the intact cold leg during a LBLOCA. During a DVI line break, the separated DVI nozzle and ECBD have the effect of preventing the level of the cooling water from being lowered in the downcomer due to an inlet-outlet reverse phenomenon at the lowest position of the outlet of the ECBD.

• Macromolecular Research
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• 제17권7호
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• pp.499-505
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• 2009

General, fast, and efficient stitching methods are presented for the synthesis of Fr$\acute{e}$chet-type dendrimers with linear units at a core, as a preliminary investigation for the synthesis of dendritic-linear-dendritic materials. The synthetic strategy involved an inexpensive, 1,3-dipolar, cycloaddition reaction between an alkyne and an azide in the presence of the Cu(I) species, which is known as the best example of click chemistry. The linear core building blocks, 1,7-octadiyne and 1,6-diazidohexane, were chosen to serve as the alkyne and azide functionalities for dendrimer growth via click reactions with the azide and alkyne-dendrons, respectively. These two building blocks were employed together with the azide- and alkyne-functionalized Fr$\acute{e}$chet-type dendrons in a convergent strategy to synthesize two kinds of Fr$\acute{e}$chet-type dendrimers with different linear core units. This comparative efficiency of the click methodology supports the fast and efficient synthesis of dendritic-linear-dendritic materials with the tailor made core unit.

• Journal of Microbiology and Biotechnology
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• 제15권3호
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• pp.544-550
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• 2005

To develop a highly efficient mammalian expression vector, a series of vectors were constructed based on the murine cytomegalovirus (MCMV) immediate-early (IE) promoter and human ${\beta}$-globin second intron. The resulting MCMV promoter was several-fold stronger than the HCMV promoter in various mammalian cell lines, such as the NIH3T3, Neuro-2a, 293T, and HT1080 cell lines, and was only slightly weaker than the HCMV promoter in HeLa and CHO cells. The inclusion of the human ${\beta}$-globin second intron behind the MCMV promoter or HCMV promoter markedly enhanced the promoter activity in various mammalian cell lines, and the resultant MCMV/Glo-I expression system was stronger than the HCMV promoter from 4.7- to 11.2-fold in every cell line tested. Also, the MCMV/Glo-I promoter induced a higher level of the VSV-G protein in a transiently transfected 293T cell line, which is useful for the production of recombinant retrovirus and lentivirus vectors.

• Ocean and Polar Research
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• 제29권4호
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• pp.411-418
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• 2007

We studied the bottom morphology and sedimentary environments of the Masan Bay using high-resolution Chirp seismic profiles and sediments data. According to deep-drilled core samples (up to 20 m thick) penetrated into the weathered rock basement, the sediments consist largely of three sediment types: the lower sandy gravel facies (Unit I) of 1-4 m in thickness, the middle sandy mud and/or muddy sand facies(Unit II) of 1-2 m thick and the upper mudfacies (Unit III) of over 10 m in thickness. The sedimentary column above the acoustic basement can be divided into two major sequences by a relatively strong mid-reflector, which show the lower sedimentary sequenc e(T) with parallel to subparallel internal reflectors and the upper sedimentary sequence(H) with free acoustic patterns. Acoustic basement, the lower sedimentary sequence (T), and the upper sequence (H) are well correlated with poorly sorted massive sandy gravels (Unit I), the sand/mud-mixed sediment (Unit II), and the muddy facies(Unit III), respectively. The acoustic facies and sediment data suggest that the Masan bay is one of the most typical semi-enclosed coastal embayments developed during the Holocene sea-level changes. The area of the Masan Bay reduced from about $19\;km^2$ in 1964 to about $13\;km^2$ in 2005 by reclamation, and its bottom morphology changed as a result of dredging of about $2{\times}10^7\;m^3$.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(1)
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• pp.403-410
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• 1995

A loss of the residual heat removal (RHR) accident during mid-loop operation of Yong-gwang Nuclear Units 3/4 was analyzed using the RELAP5/MOD3.1.2 code. In this work the following assumptions are used; (i) initially the reactor coolant system (RCS) above the hot leg center line is filled with nitrogen gas, (ii) two 3/4-inch diameter vent valves on the reactor vessel head and the top of pressurizer in the reactor coolant system are always open, and a level indicator is connected to the RMR suction line, (iii) the two steam generators are in wet layup status and the steam generator atmospheric dump valve assemblies are removed so that the secondary side pressure remains at nearly atmospheric condition throughout the accident, and (iv) the loss of RHR is presumed to occur at 48 hours after reactor shutdown. Findings from the RELAP5 calculations are (i) the core boiling begins at ∼5 min, (ii) the peak RCS pressure is ∼3.0 bar, which implies a possibility of temporary seal break, (iii) ∼94 % of the decay heat is removed by reflux condensation in the steam generator U-tubes in spite of the presence of noncondensable gas, (iv) the core uncovery time is evaluated to be 7.2 hours. Significant mass errors were observed in the calculations.

• 한국과학교육학회지
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• 제30권8호
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• pp.1031-1043
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• 2010

이 연구의 목적은 과학 교수-학습프로그램의 두뇌 기반 분석을 위한 정성적 정량적 분석방법을 제시하는 것이다. 연구목적 달성을 위해, 첫 번째로 두뇌기반 분석을 위한 분석방법의 고안에는 중학교 과학 교수-학습프로그램 중 한 단원을 연구대상으로 선정하여 분석하였다. 제시된 분석방법의 유용성 검증에는 7차 및 2007 개정 교육과정의 초등학교 과학 교수-학습프로그램 중 네 단원을 연구대상으로 선정하여 검증하였다. 그 결과, 교수-학습 프로그램을 CORE Brain Map을 통해 정성적으로 컨설팅 할 수 있었다. 또한 네트워크 이론으로부터 정량적 분석을 위한 두뇌맞춤지수 산출식(BCI=$\frac{L_o}{11(N_o-1)}{\cdot}{\sum}\limits_{i=1}^4l_iw_i$)을 유도하였다. 이를 통해 단원 및 교육과정에 따른 연구대상 교수-학습프로그램들 간의 정량적 차이를 확인할 수 있었다. 이 연구를 통해 개발된 두뇌기반 과학 교수-학습 프로그램의 정성적 정량적 분석방법은 두뇌기반 다양한 과학 교수-학습 프로그램의 분석 및 진단에 활용 가능할 것으로 전망된다.

• 대한치과보철학회지
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• 제22권1호
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• pp.7-15
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• 1984

A rationale and compendium of treatment for a specific situation of cases have been presented. It consists of a cast metal bar called a truss bar joint removable denture which is soldered to crowns and dowel core on a few remaining teeth, i.e., cuspids or bicuspids. This system gives additional support and retention to the individual teeth and makes possible a more stable removable denture. It is my opinion that the prognosis of the chosen cases may be obtained Successful results when applied on the teeth of less favorable crown-root ratio.

• 자원환경지질
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• 제39권1호
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• pp.53-61
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• 2006

Geochemical and sedimentological analyses of sediment piston core were used to trace paleoceanographic environmental changes in the East China Sea. The analytical results revealed three lithostratigraphic units (I, II, and III) corresponding to a highstand stage, a transgressive stage, and a lowstand stage, respectively. Accelerator mass spectrometry (AMS) $^{14}C$ dated the boundaries between the units as 7 ka and II ka. That is, Unit I extended from the present to 7 ka, Unit II occupied a transitional episode from 7 to 11 ka, and Unit III was older than 11 ka. The transitional episode was characterized by sudden fluctuations in various geochemical proxies. Most strikingly, there was a gradual upward increase in both carbonate and total organic carbon (TOe) contents post-7 ka, during which time the ${\delta}^{l3}C$ values of organic material increased to a constant value. The gradual upward increase in the TOC and $CaCO_3$ contents in Unit I were accompanied by slight variations in grain size that probably reflect a stable modern oceanographic environment. Within Unit II (7 to 11 ka), the geochemical signals were characterized by abrupt and steep fluctuations, typical of a transgressive stage. Vertical mixing may have provoked an increase in productivity during this interval, with large amounts of terrigenous organic matter and/or freshwater being supplied by neighboring rivers. The geochemical signals remained stable throughout Unit III but exhibited different patterns than signals in Unit I. The high terrigenous organic matter content of Unit III suggests correspondence to a lowstand stage.

• 한국항공운항학회:학술대회논문집
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• 한국항공운항학회 2016년도 춘계학술대회
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• pp.196-196
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• 2016

본 논문에서는 수직 회피에 사용되고 있는 Traffic Alert and Collision Avoidance System(TCAS)와 수평 회피 알고리즘을 객체지향 언어로 구현하였고, 구현된 소프트웨어의 검증을 위해 Intel-core i5-4세대 프로세서와 8GB의 메모리카드 그리고 Window7 OS 환경에서 확인하였다.