• Proceedings of the KWS Conference
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• 2005.11a
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• pp.138-140
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• 2005

Plasma arc welding(PAW) technology is a proven process that has already been adopted by other industrial fields and recently has been considered to join the tank structure of LNG carrier. The purpose of this study is to introduce PAW process for the root welding of stainless steel pipes instead of TIG welding. There are distinctive features of the PAW compared to TIG welding; higher energy density that can increase welding speed by more than twofold, and longer arc length that can be controlled to trace seam line easily because of allowable gap between workpiece and torch. However, PAW process is also very sensitive to the root gap and misalignment due to the characteristics of long and narrow arc shape. So, we have done various experiments to establish the allowable fit-up condition by changing welding parameters including arc length, with or without filler metal, groove shape, and obtained satisfactory result.

• Economic and Environmental Geology
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• v.32 no.1
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• pp.33-41
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• 1999

A new sedimentary basin is reported from the marine multi-channel seismic data which were acquired for the hydrocarbon exploration on the southwestern Korean continental shelf in 1970. Along the southeastern part of Line 1192, the about 60-km-long basin with the thickness of 0.55~1.1 s is observed on the near-trace gather. However, both new and previous 24-fold stack sections fail to show the basin image probably due to its rugged top beneath the shallow water. The boundary contact between the basement with the velocity of about 5200m/s and the basin filling with the velocities of 4300~4700 m/s is unclear. These velocites are calculated from the corresponding shot gathers. Compared with the Haenam Basin, a neighbouring onshore Cretaceous sedimentary basin, we interpret that the new basin includes the volcanics and volcaniclastic sequences deposited in the lacustrine environment. This nonmarine basin was possibly formed as the result of the tectonic movement during the Cretaceous, implying the wide occurrence of the Cretaceous basins over the southern Korean Peninsula as well as its southwestern continental shelf.

• International Journal of Aeronautical and Space Sciences
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• v.9 no.1
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• pp.1-30
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• 2008

When the stagnation temperature of a perfect gas increases, the specific heats and their ratio do not remain constant any more and start to vary with this temperature. The gas remains perfect; its state equation remains always valid, except, it is named in more by calorically imperfect gas. The aim of this work is to trace the profiles of the supersonic axisymmetric Minimum Length Nozzle to have a uniform and parallel flow at the exit section, when the stagnation temperature is taken into account, lower than the dissociation threshold of the molecules, and to have for each exit Mach number and stagnation temperature shape of nozzle. The method of characteristics is used with the algorithm of the second order finite differences method. The form of the nozzle has a point of deflection and an initial angle of expansion. The comparison is made with the calorically perfect gas. The application is for air.

• 연구논문집
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• s.33
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• pp.89-97
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• 2003

A barrel cam is used as a very important part of an index drive unit. The index drive unit must have an intermittent-rotational motion. The barrel typed cam and roller gear mechanism has the advantages of high reliability to perform a prescribed motion of a follower. This paper proposes a new method for the shape design of the barrel cam and also a CAD program is developed by using the proposed method. As defined in this paper, the relative velocity method for the shape design calculates the relative velocity of the follower versus cam at a center of roller, and then detemines a contact point by using the geometric relationships and the kinematic constraints, where the direction of the relative velocity must be parallel to a common tangential line at the contact point of two independent bodies, i.e. the cam and the follower. Then, the shape of the cam is defined by the coordinate transformation of the trace of the contact points. This paper presents shape design of the barrel cam in order to prove the accuracy of the proposed methods

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.72.1-72.1
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• 2016

Current and planned large-volume surveys such as the Sloan Digital Sky Survey extended Baryon Oscillation Spectroscopic Survey (SDSS IV-eBOSS) or the Dark Energy Spectroscopic Instrument (DESI) will use Luminous Red Galaxies (LRGs) and Emission Line Galaxies (ELGs) to map the cosmic web up to z~1.7, and will allow one to accurately constrain cosmological models and obtain crucial information on the nature of dark energy and the expansion history of the Universe in novel epochs - particularly by measuring the Baryon Acoustic Oscillation (BAO) feature with improved accuracy. To this end, we present here a study of the spatial distribution and clustering of a sample of LRGs and ELGs obtained from a sub-volume of the MultiDark simulation complemented by different semi-analytic prescriptions, and investigate how these two different populations trace the cosmic web at different redshift intervals - along with their synergy. This is the first step towards the interpretation of upcoming ELG and LRG data.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1908-1909
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• 2007

The design of an intelligent toothbrush, capable of monitoring brushing motion, orientation through the grip axis, during toothbrushing is described. Inappropriate Toothbrushing styles, even in adults, sometimes cause dental problems, cavities, gingivitis, etc. This smart system provides user to monitor his or her brushing pattern using accelerometer and magnetic sensors for evaluation of toothbrushing style. Directional information of toothbrush with respect to earth's magnetic field and activity data were measured by a miniaturized low-power micro- controller, MSP430 and transmitted to personal computer by 2.4GHz radio transmitter, nRF2401. A personal computer provides an on-line display of activity and orientation measurements during toothbrushing. The signal trace is then analyzed to extract clinically relevant measurement. This preliminary study showed that the proposed monitoring system was conceived to aid dental care personnel in patient education and instruction in oral hygiene regarding brushing style.

• Bulletin of the Korean Chemical Society
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• v.9 no.2
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• pp.77-80
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• 1988

A suituable choice of supporting electrolyte medium for trace level determinations of chromium(VI) by differential pulse polarography is described. A comparative study suggests that sodium borate buffer is superior to ammonium acetate, ammonium tartrate, and especially to NaF which was recently known to be one of the most proper medium for the purpose. With 0.01 M borate, the best combination of high sensitivity, well-defined base line, and freedom from common interferents was attained. With $5.0{\times}10^{-7}$M Cr(VI), tenfold excesses of Cu(II) and Fe(III), and a five hundred-fold excess of $Cl^-$ do not change the peak current by more than about 1%. And the detection limit was $5.0{\times}10^{-8}$M Cr(VI).

• Bulletin of the Korean Chemical Society
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• v.20 no.9
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• pp.1040-1044
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• 1999

A micro porous PTFE membrane desolvator (MMD) was built and evaluated for the on-line removal of organic solvents to facilitate the determination of trace metal contaminants in the solvents by ICP-AES. Three organic solvents, isopropyl alcohol (IPA), methanol, and dimethy sulfoxide (DMSO) were studied. The MMD reduced organic solvent concentration in the sample aerosol stream by 82% to 89%, as indicated by monitoring C(I) emission. Net signal intensity of Fe, Al, and Cu was increasing with higher organic solvent concentration, with the rate of increase being solvent dependent. The signal intensities for Mg and Pb followed the trend with the C(I) signal. Changing the sweep gas flow rate affected the optimum signal intensity. Wine samples were analyzed by the method of standard addition. The concentrations of B, Al, and Mg were determined with a relative precision of less than 2.3%.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.299-302
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• 2009

이 논문에서는 라인 트레이스 차량의 주행 제어를 위한 퍼지 제어기를 설계하였다. 라인을 감지하는 센서들의 감지 상태에 따라 센서값을 산출하고 이 센서값은 조향각 제어 퍼지 규칙의 입력으로 사용되어 조향각을 제어값으로 산출한다. 또한 산출된 조향각은 다시 모터속력 제어 퍼지 규칙의 입력으로 사용되어 주행 속도 결정을 위한 모터속력을 제어값으로 산출하게 된다. 제안한 퍼지 제어 기법을 이용하여 조향각만을 제어한 경우와 조향각과 모터속력을 함께 제어한 경우를 각각 실험한 결과, 모터속력을 함께 제어한 경우가 트랙을 이탈하지 않으면서 더욱 빠르게 주행함으로써 제안한 기법에 효과적임을 보였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.01a
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• pp.485-486
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• 2023

4차 산업혁명 이전에도 많은 물류 자동화가 이루어지고 있었다. 그러나 4차 산업혁명이 도래하면서 자동화되는 범위가 더욱 넓어지며 인력이 쓰이는 곳에 로봇이 대거 등장하게 되었다. 그러나 환경이 열악한 중소기업이나 경제성 측면에서의 도입이 어려운 분야에서는 자동 물류 시스템의 적용이 어려운 것이 현실이다. 본 논문에서는 이러한 문제를 해결하기 위해 물건을 옮기는 일에 있어서는 라인트레이서를 이용하여 물품의 수송을 도와주고, 적외선 센서 및 바코드 리더기를 이용하여 물품 개수의 현황 계산을 담당하여 정확한 계산을 도출하여 자동으로 원격 데이터베이스에 저장하여 관리할 수 있는 물류관리 지원 시스템을 제안한다.