• 설비공학논문집
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• 제20권3호
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• pp.181-188
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• 2008

The effect of inclination angle on the heat transfer and pressure drop characteristics of the brazed aluminum heat exchangers is experimentally investigated. Three samples having different fin pitches(1.25, 1.5 and 2.0 mm) were tested. Results show that heat transfer coefficient is not affected by the inclination angle. However, the friction factor increases as the inclination angle increases with negligible difference between the forward and backward inclination. Both the heat transfer coefficient and the friction factor are the smallest at $F_p=1.5mm$, followed by $F_p=2.0mm$ and 1.25mm. Possible explanation is provided considering the louver layout. Comparison with existing correlations is also made.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.222-228
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• 2007

The effect of inclination angle on the heat transfer and pressure drop characteristics of brazed aluminum heat exchangers is experimentally investigated. Three samples having different fin pitches (1.25, 1.5 and 2.0 mm) were tested. Results show that heat transfer coefficient is not affected by the inclination angle. However, the friction factor increases as the inclination angle increases with negligible difference between the forward and backward inclination. Both the heat transfer coefficient and the friction factor are the smallest at $P_f$=1.5mm, followed by $P_f$=2.0mm and 1.25mm. Possible explanation is provided considering the louver layout. Comparison with existing correlations is also mad.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
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• pp.88-91
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• 2000

An MMIC oscillator operating at the 24.55 GHz has been designed using 0.2 ${\mu}{\textrm}{m}$AlGaAs/InGaAs/GaAs Pseudomorphic HEMT technology. The active device used in the oscillator design has a 0.2 ${\mu}{\textrm}{m}$ gate length PHEMT with 4$\times$80 ${\mu}{\textrm}{m}$ gate width. We obtained 4.08 dB of S$_{21}$ gain and 317 mS/mm of transconductance, and extrapolated unit current gain cut-off frequency (f$_{T}$) and maximum oscillation frequency (fmax) were 62 GHz and 120 GHz, respectively. The circuit are based on a series feedback and negative resistance topology. Microstrip line open stub is used to terminating. The oscillator circuits has designed for delivering maximum power to load and conjugated matching. The simulated small signal negative resistance was 50 Ω. We obtained 1.002 of loop gain and 0.0005$^{\circ}$angle from the simulation by HP libra 6.1. The layout for oscillator is 1.2$\times$1.8 $\textrm{mm}^2$.>.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권2호
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• pp.102-106
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• 2005

A low dark current CMOS image sensor (CIS) pixel without any process modification is developed. Dark current is mainly generated at the interface region of shallow trench isolation (STI) structure. Proposed pixel reduces the dark current effectively by separating the STI region from the photodiode junction using simple layout modification. Test sensor array that has both proposed and conventional pixels is fabricated using 0.18 m CMOS process and the characteristics of the sensor are measured. The result shows that the dark current of the proposed pixel is 0.93fA/pixel that is two times lower than the conventional design.

• 품질경영학회지
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• 제19권1호
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• pp.163-169
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• 1991

This paper studies computer programming for Two-Way Layout with Multiple Observations - Fixed Model using the subroutines of the former paper. The following items are considered in the PC computer programming: * significant digits in the computation of Sum of Squares * containing the necessary F-distribution values in the program * including the necessary estimation after the Analysis of Variance * following the rules of KS A 0021 in rounding off digits etc. The running results of Analysis of Variation Table and Estimations of a fictitious example is added with the parts of PC program. It should be mentioned that the main purpose of this paper is in the arousing of the discussion about significant digits concept in the PC computer programming for various kinds of Statistical Methods.

• 한국컴퓨터정보학회논문지
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• 제23권5호
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• pp.1-7
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• 2018

Reference string recognition is to extract individual reference strings from a reference section of an academic article, which consists of a sequence of reference lines. This task has been attacked by heuristic-based, clustering-based, classification-based approaches, exploiting lexical and layout characteristics of reference lines. Most classification-based methods have used sequence labeling to assign labels to either a sequence of tokens within reference lines, or a sequence of reference lines. Unlike the previous token-level sequence labeling approach, this study attempts to assign different labels to the beginning, intermediate and terminating tokens of a reference string. After that, post-processing is applied to identify reference strings by predicting their beginning and/or terminating tokens. Experimental evaluation using English and German reference string recognition datasets shows that the proposed method obtains above 94% in the macro-averaged F1.

• Structural Engineering and Mechanics
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• 제82권5호
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• pp.595-609
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• 2022

Prestressed composite steel-concrete beams are still a technology restricted to repair sites of large-scale structures and spans. One of the reasons for that is the absence of standard frameworks and publications regarding their design and implementation. In addition, the primary normative codes do not address this subject directly, which might be related to a scarcity of papers indicating methods of design that would align the two technics, composite beams and external prestressing. In this context, this paper proposes methods to analyze the sizing of prestressed composite beams submitted to pre-tension and post-tension with a straight or polynomial layout cable. This inquiry inspected a hundred and twenty models of prestressed composite beams according to its prestressing technology and the eccentricity and value of the prestressing force. The evaluation also included the ratio between span and height of the steel profile, thickness and typology of the concrete slab, and layout of the prestressing cables. As for the results, it was observed that the eccentricity of the prestressing force doesn't significantly influence the bending resistance. In prestressed composite beams subjected to a sagging moment, the ratio L/d can reach 35 and 30 for steel-concrete composite slabs and solid concrete slabs, respectively. Considering the negative bending moment resistance, the value of the L/d ratio must be less than or equal to 25, regardless of the type of slab. When it comes to the value of the prestressing force, a variation greater than 10% causes a 2.6% increase in the positive bending moment resistance and a 4% decrease in the negative bending moment resistance. The pre-tensioned composite beams showed a superior response to flexural-compression and excessive compression limit states than the post-tensioned ones.

• Journal of Mechanical Science and Technology
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• 제15권3호
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• pp.291-299
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• 2001

Recently, severe wear on the shutdown rod cladding of Ulchin Nuclear Power Plant #1, #2 were observed by the Eddy Current Test(E.C.T.). In particular, the wear at the sixth card location was up to 75%. The test results indicated that the Flow Induced Vibration(F.I.V.) might be the cause of the fretting wear resulting from the contact between Rod Cluster Control Assemblies(RCCAs) and their spacing cards(guide plates) arranged in the guide tube. From reviewing RCCAs fretting wear repots and analyzing the general characteristics of F.I.V. mechanism in the reactor, geometric layout and flow conditions around the control rod, it is concluded that the turbulence excitation is the most probable vibration mechanism of RCCA. To identify the governing mechanism of RCCA vibration, an experiment was performed for a representative rod position in which the most serious fretting wear experienced among the six rod positions. The experimental rig was designed and set up to satisfy the governing nondimensional numbers which are Reynolds number and mass damping parameter. The vibration amplitude measurement by the non-contact laser displacement sensor showed good agreements in the frequency and the maximum wearing(vibration) location with Ulchin E.C.T. results and Framatome report, respectively. The sudden increase in the vibration amplitude was sensed around the 6th guide plate with mass flow rate variation. Comparing the similitude rod behaviour with the idealized response of a cylinder in flow induced vibration, it was found that he dominant mechanism of vibration was transferred from turbulence excitation to periodic shedding at the mass flow ate 90ι/min. Also the critical velocity of the vibration in RCCAs was determined and the vibration can be prevented by reducing the bypass flow rate below the critical velocity.

• 한국정보통신학회논문지
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• 제15권3호
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• pp.521-527
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• 2011

군용 Single Board Computer(이하 SBC)에 주로 사용되는 중앙 처리 장치(Central Processing Unit)는 주로 Power PC의 계열이며 Freescale 사의 G4 계열인 74xx 프로세서가 주로 사용된다. 이러한 CPU인 7447A는 System Controller를 통하여 SBC 내의 주 기억 장치와 고속으로 데이터를 주고받는다. 본 논문에서는 위와 같은 SBC의 구조에서 System Controller와 DDR 메모리 소자 간 I/F를 구현함에 있어 PCB 적층 구조, 소자들의 Layout, 임피던스매칭과 Rugged 환경에서 적용 되는 동작 가능한 DDR 메모리를 모듈로 설계하여 구현하였다. 또한, 군용환경에 적용하기위한 SBC의 형상은 주로 6U, 3U의 표준 형태로 설계되어져야 한다. 메모리의 단종을 대비하여 메모리를 모듈화하고 System Controller와 모듈간의 최적의 전기적인 I/F매칭과 신호의 cross over를 고려한 Artwork반영, 존재하는 PCB의 제한조건을 고려해서 시뮬레이션과 설계 및 구현하는 방안을 제안한다.

• 한국실내디자인학회논문집
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• 제21호
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• pp.89-93
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• 1999

A museum architecture has been developed as important representation of a specific period in architectural history. Modern concept of museum architecture has started by Karl Fredrich van Schinkel(1781-1841) through das Altes Museum(1823-1830) back in early 20th century and it continues to be the model for museum architecture for over 30 years. By middle of the 20th century, the movement of redefining new model for the new era on the subject of museum architecture was developed. This development was lead by the three masters of the modern architecture at the time. F.L. Wright, Corbusier, Mies and they were responsible and very active in creating new concepts. Their works in museum design became the prototype and they tried hard to make sure their new concepts to be the stepping stone for further development. This study is to compare the three different museums designed by those masters of the modern architecture, particularly on the issue of the exhibition spaces. The purpose of the study will be focused on the point of interior architecture such as the matters of layout and design characteristics of the exhibition spaces. And it will reveal the impact made by those masters on the advanced development of the current generations of museum designers as well as to describe the prototype of exhibition space. The analyzation was done on FLW's Guggenheim Museum in New York, Corbusier's the National Museum of Western Art in Tokyo, and Mies' Die Neue National Galerie in Berliv. Comparable materials were collected through site visits and reference documents from various publications. It will be ideal if this study can be used for further development in new museum design in this country.