• 대한기계학회논문집B
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• 제21권2호
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• pp.195-201
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• 1997

Static and non-static flame methods were used to measure the laminar burning velocity of methane, ethane and natural gas. The flame slot angle and velocity of unburned gas mixture were determined by Schlieren method and LDV, respectively, for static flame. The diameter of nozzle was selected as 11 mm. The experimental results containing the stretch effect showed that the maximum burning velocities were 41.5 for natural gas, 40.8 for methane and 43.4 cm/sec for ethane on equivalence ratio of 1.1. Constant volume combustion chamber was also used for non-static flame. The propagation process of flame front was visualized by high speed camera during constant pressure. The maximum burning velocity of natural gas was determined as 42.1 cm/sec on equivalence ratio of 1.15.

• 한국대기환경학회지
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• 제19권5호
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• pp.515-528
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• 2003

The characteristics of one year observation aerosol data in Seoul, 200 I was studied using an OPC (Optical Particle Counter). The size resolved aerosol number concentrations of 0.3 ∼ 25 11m were measured. The results were compared with PM$_{10}$ mass concentration data under various meteorological conditions including dust and precipitation events. For fine particles whose diameter is less than 2.23 ${\mu}{\textrm}{m}$, the number concentration increases in the early morning which is considered due to transportation. while the coarse mode particles increase during daytime. This increase can be explained as local sources and human activities near sampling site. Hourly averaged data show that there exists diurnal variation. Generally, PM$_{10}$ data showed a similar tendency with OPC data. The size resolved OPC data showed that the particles of 0.5 ∼ 3.67 ${\mu}{\textrm}{m}$ are positively correlated with PM$_{10}$ data. The accumulated volume fraction of size resolved aerosol concentration in 0.5 ∼ 10 ${\mu}{\textrm}{m}$ showed that 0.5 ∼ 2.23 ${\mu}{\textrm}{m}$ particles occupied 59.2% of total aerosol volume of 0.5 ∼ 10 ${\mu}{\textrm}{m}$./TEX>.

• 한국산업융합학회 논문집
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• 제2권1호
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• pp.121-130
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• 1999

It is necessary to measure pressure, temperature, chemical equilibrium and the shape of flame in order to understand the combustion process in a combustion chamber. In particular, the flame formulation and combustion process of divided combustion chamber are different from those of a single chamber, And the variable diameter of a jet hole can effect not only physical properties like ejection velocity, temperature and time of combustion but also a chemical property like the reaction mechanism. Accordingly temperature is one of the most important factors which influence the combustion mechanism. This paper observed shape of flame by using the schlieren photographs and measured the pressure in a combustion chamber and the reaching time of the flame by ion probe By doing these, we investigation the formulation of the flame and the process of propagation. These measurement methods can be advanced in understanding the combustion process and process and propagation of flame.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.153-156
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• 2005

Nondestructive sensing of electrospun PYDF web and multi-wall carbon nanotube (MWCNT)/epoxy composites were investigated using electro-micromechanical technique. Electrospinning is a technique used to produce micron to submicron diameter polymeric fibers. Electrospun PVDF web was also evaluated for the sensing properties by micromechanical test and by measurement electrical resistance. CNT composite was especially prepared for high volume contents, 50 vol% of reinforcement. Electrical contact resistivity on humidity sensing was a good indicator for monitoring as for multifunctional applications. Work of adhesion using contact angle measurement was studied to correlate acid-base surface energy between carbon fiber and CNF composites, and will study furher for interfacial adhesion force by micromechanical test.

• 한국컴퓨터정보학회논문지
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• 제25권5호
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• pp.137-146
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• 2020

20대 미혼 여성 182명의 직접 계측치를 이용한 유방유형 분류에 유방전체 형상 요인, 유방상부내측형상 요인, 유방볼륨 요인, 유방하부외측형상 요인 등 4가지 요인이 추출되었다. 군집분석을 통해 '상부발달 유방', '밋밋한 유방', '하부 발달 유방', '돌출한 유방' 등 4유형의 유방유형으로 분류하였다. 유방유형은 목앞점~젖꼭지점길이, 목옆점~젖꼭지점길이, 유방안쪽점 사이간격, 젖꼭지 간격, 유방아래직경, 유방내측깊이, 유방바깥쪽길이, 유방아래길이, 젖가슴가쪽점~젖가슴위쪽점길이, 젖가슴 밑 윤곽선길이 등 10개 항목으로 판별 가능하다.

• 한국연소학회지
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• 제8권4호
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• pp.1-8
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• 2003

In this study, the quantification of soot particles in laminar diffusion flame with LII/LIS methods was performed. In these quantification, soot diameter, number density and volume fraction are included. For the quatification of soot particles, calibration tests are needed and the development of algorithm has to be performed. So, in this study, extinction and scattering test at co-flow burner were performed to acquire calibration data. And algorithm for LII/LIS simultaneous measurement for the quantification of soot were developed. The algorithm, which was the quantification of simultaneous photographing using one ICCD camera, to measure LII/LIS signal simultaneously, the best fitted light intensity and acquisition time was needed.

• 한국주조공학회지
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• 제14권1호
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• pp.62-74
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• 1994

The concentration and particle size distribution of non-metallic inclusions which suspended in the molten aluminum at $700^{\circ}C$ were measured by using LiMCA apparatus. The result revealed that the number of inclusions increased with increasing the applied current or decreasing the orifice diameter, while decreased with increasing the purity of aluminum. And also, it was found that the number of inclusions increased with increasing the amount of boron added to molten aluminum. This was found to be attributed to the formation of the inclusions of TiB and $V_3B_2$. It was investigated that the average concentration of inclusions in a constant volume of 20ml of molten aluminum was increased in the order of pure molten aluminum, molten aluminum containing 20ppm of boron and molten aluminum used repeatly in the experimental casting in this study.

• 전기학회논문지
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• 제67권1호
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• pp.131-136
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• 2018

Reliable velocity estimation technology for trains is one of technologies used to operate trains safely and effectively. Various sensors such as tachometers, doppler radars, and global positioning systems are used to estimate velocity of a train. Tachometer is widely used to estimate velocity of a trains due to its simplicity, small volume, cost-effectiveness, continuously measurement at high speed, and robustness against noise. Accuracy in the velocity calculation using a tachometer depends on quantization error, measurement error of wheel radius or diameter, and tachometer's imperfection from manufacturing or installation process. In this paper, we present an accurate velocity estimation method using a low-resolution tachometer, which is commonly installed on a high-speed train. Baseline estimation method is proposed to accurately calculate the velocity of the high-speed train from tachometer's pulses. HEMU-430x test train is used for the experiment and verification of the proposed method. Experimental results with several routes show that the proposed method is more accurate than a conventional method.

• 한국콘텐츠학회논문지
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• 제15권6호
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• pp.276-282
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• 2015

태아의 소뇌는 임신주수에 따라 성장하며 소뇌횡직경 길이의 측정은 임상에서 태아성장 예측의 중요한 지표로 활용하고 있다. 본 연구에서는 임신 20~37주 사이의 산모를 임신 주수별 각 20명씩 총 340명을 대상으로 3차원초음파 탐촉자를 이용하여 태아의 태령 및 태아의 소뇌 양쪽 외단을 측정해 기초자료를 획득하였다. 결과적으로 임신 주수에 따른 태아 소뇌횡직경의 성장을 회귀곡선으로 표시하였고 선형회귀방정식에서 결정계수를 얻었다. 3차원초음파를 이용한 임신주수에 따른 소뇌횡직경 측정방법은 통계적으로 유의(p<0.001)하였으며, 태령을 예측함에 있어 유용하다는 것을 알 수 있었다. 그러므로 임신주수에 따라 증가하는 소뇌횡직경의 측정은 정확한 임신주수의 산정이 가능 할 것이며 임상에서 현재 이용되고 있는 태령측정 방법의 대체 또는 개선방법이라 사료된다. 태아의 성장에 따라 측정하는 소뇌형직경은 임신주수에 따른 태아 성장의 평가가 가능하며, 태아의 머리 모양에 관계없이 성장장애가 있는 경우에도 임신주수의 예측이 가능하다. 따라서 본 연구를 기초자료로 하여 지속적인 연구가 시행된다면 3차원초음파를 이용한 소뇌횡 직경의 측정은 정확한 임신주수 예측에 유용할 것으로 사료된다.

• 한국자동차공학회논문집
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• 제5권3호
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• pp.54-65
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• 1997

To quantify the LII signals from soot particle of flames in diesel engine cylinder, a new method has been proposed for correcting LII signal attenuated by soot particles between the measuring point and the detector. It has been verified by an experiment on a laminar jet ethylene-air diffusion flame. Being proportional to the attenuation, the ratio of LII signal at two different detection wavelengths can be used to correct the measured LIIsignal and obtain the unattenuated LII signal, from which the soot volume fraction in the flame can be estimated. Both the 1064-nm and frequency-doubled 532-nm beams from the Nd : YAG laser are used. Single-shot, one-dimensional(1-D) line images are recorded on the intensified CCD camera, with the rectangular-profile laser beam using 1-mm-diameter pinhole. Two broadband optical interference filters having the center wavelengths of 647 nm and 400 nm respectively and a bandwidth of 10 nm are used. This two-wavelength correction has been applied to the ethylene-air coannular laminar diffusion flame, previously studied on soot formation by the laser extinction method in this laboratory. The results by the LII measurement technique and the conventional laser extinction method at the height of 40 nm above the jet exit agreed well with each other except around outside of the peaks of soot concentration, where the soot concentration was relatively high and resulting attenuation of the LII signal was large. The radial profile shape of soot concentration was not changed a lot, but the absolute value of the soot volume fraction around outside edge changed from 4ppm to 6.5 ppm at r=2.8mm after correction. This means that the attenuation of LII signal was approximately 40% at this point, which is higher than the average attenuation rate of this flame, 10~15%.