• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 1991년도 추계학술발표회논문집
• /
• pp.28-32
• /
• 1991

This paper reports the characteristics of sparkover discharge in flowing air with variation of Temperature(T). Also, We studied changes of discharge pattern for constant input power by adjustment of the reynolds number(Re) and T. the essentials of this paper are as followers. The invaluable equation obtained from this experiment is [%] {{{{ { Vs} over {Re } = A·LOG10 Re + B}}}} w here A,B : constant Breakdown Voltage for variation of temperature at 1[m/s] is given by expression Vs = K(23.98 pd + 6.8{{{{ SQRT { pd} }}}}) [kV] where K = 0.331 The discharge pattern can be controlled by adjustment of the Reynolds number

• 한국공작기계학회논문집
• /
• 제14권6호
• /
• pp.68-73
• /
• 2005

Tire manufactures have dealt with noise problem by varying the pitch of the tread. The various formulas for the variations are generally determined differently, however. Often these variations are based on a combination of trial and error, intuition, and economics. Some manufactures have models and analogs to test tread patterns and their variations. These efforts, however practical, do not determine the best variation beforehand or guarantee the best results. For this reason it was felt that a general mathematical approach fur determining the best variation was needed. Moreover, the method should be completely general, easy to use, and sufficiently accurate. This paper discusses a mathematical method called Mechanical Frequency Modulation(MFM) which meets the above requirements. Thus, MFM pertains to computing an irregular time sequence of events so that the resulting excitation spectrum is shaped to a preferred form. The first part of this paper treats the theoretical basis for computing an optimum variation ; the second part discusses experimental results and simulation program which corroborate the theory.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2007년도 하계학술대회 논문집
• /
• pp.412-414
• /
• 2007

In motor driving, one of the most important consideration is the load characteristic and variation. Generally, the motor drive should be made enough for the current by load variation, and it should be controlled by the load weight. However, the drum washing machine's load variation is irregular and large. Therefore, we want to make the motor drive that considering this load pattern, this paper describes the drum washing machine's load pattern modeling by the mathematical theory.

• 한국전기전자재료학회논문지
• /
• 제22권2호
• /
• pp.119-122
• /
• 2009

As infrared light radiates, the CMOS Readout IC (ROIC) for the microbolometer typed infrared sensor detects voltage or current which is caused by the variation of resistance in the bolometer sensor. A serious problem we may have in designing the ROIC is the value of bolometer and reference resistors will be changed due to process variation. Since each pixel does not have the same value of resistance, fixed pattern noise problems happen during the sensor operations. In this paper, we propose a novel technique to compensate the fluctuation of reference resistance with taking account of process variation. By using a comparator and a cross coupled latch, we will make the value of reference resistor same as the bolometer's.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
• /
• pp.438-446
• /
• 1999

Crop minimization of the top and bottom ends of hot rolled plate, in a plate, in a plate mill, has been investigated. The existing model to determine the edging pattern at the finishing rolling pass was not reasonable to get high width accuracy and rolling yields. New models including width prediction have been formulated by using neural network model of back propagation learning algorithm and statistical analysis based on the actual production rolling data to give the optimal pattern for minimizing trimming loss. Using these models, at a given rolling condition of broadside pass and finishing pass and the permissible condition of width variation, it was possible to minimize crip at the top and bottom ends according to optimum procedure in plate mill. An application to improve the plan view pattern reduced width variation by 23% and crop length by 30% on average with an effective fishtail crop shape.

• International Journal of Reliability and Applications
• /
• 제10권1호
• /
• pp.1-15
• /
• 2009

Even though the impact of manufacturing quality to reliability is not considered much as well as that of design area, a major cause of an early failure of the product is known as manufacturing problem. This research applies two different types of neural network algorithms, the Back propagation (BP) algorithm and Learning Vector Quantization (LVQ) algorithm, to identify and classify the nonrandom variation pattern on the control chart based on knowledge-based diagnosis of dimensional variation. The performance and efficiency of both algorithms are evaluated to choose the better pattern recognition system for auto body assembly process. To analyze hundred percent of the data obtained by Optical Coordinate Measurement Machine (OCMM), this research considers an application in which individual observations rather than subsample means are used. A case study for analysis of OCMM data in underbody assembly process is presented to demonstrate the proposed knowledge-based pattern recognition system.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
• /
• pp.438-440
• /
• 2003

This study is introducing a new approach of ATInSAR hologram for modeling wave refraction spectra pattern. TOPSAR data with L$_{-HH}$ and C-vv bands utilized spatial variation of wave refraction. Based on the phase information in along track interferometry, and ATInSAR hologram the quantitative information such swell wave height and spectra energy have been modeled. The phase information in ATInSAR hologram images can be transferred to wave refraction The ATInSAR hologram can be used to investigate the wave refraction pattern along the coastal waters. The fringe information pattern was shown to be useful in modeling wave refaction spectra varaition. The hologram interferometry wave refraction model consists of two sub-models. The purpose of first sub-model is to determine the swell wave height by using ATInSAR. Second sub-model aims to generate the holographic interferometry from the information of two wave spectra which detected by ATInSAR technique. The azimuth cut-off variations along the fringe patterns will be estimated. As azimuth cut-off contains the wave height information which could be used the significant wave height variation in convergence and divergence zone.

• 한국지리정보학회지
• /
• 제17권4호
• /
• pp.112-128
• /
• 2014

본 연구에서는 구미시를 사례로 매개 변수값의 변화에 따른 2SFCA(2 Step Floating Catchment Area) 기반 접근성 변화의 지역 특성을 분석하였다. 2SFCA는 기본인구가 증가하면 접근성이 감소하고, PPR(Provider to Population Ratio)이 증가하면 접근성이 증가하는 일반적인 경향을 보였다. 구미시 내부의 지역 특성을 분석하기 위해서 민감도 분석 과정에서 군집분석을 수행하였다. 지역 특성은 다음과 같다. 첫째, 구미시 읍면 외곽지역처럼 노인복지시설과 멀리 떨어져 있는 지역은 매개 변수값의 변화에 따른 접근성 변화가 미미하였다. 둘째, 기존 노인복지시설 주변 지역은 매개 변수값의 변화에 따라 접근성이 개선되거나 약화되는 다양한 양상을 보였다. 노인인구가 많고 노인복지시설이 밀집해 있는 동 지역에서는 PPR의 변화에 따른 접근성 변화가 크고, 나머지 지역은 기본인구 변화에 따른 접근성 변화가 크게 나타났다. 셋째, 매개 변수값이 커지면 여러 곳의 노인복지시설을 이용할 수 있는 구미시 중앙구역에서 전반적으로 접근성이 양호해지는 양상을 보였다. 향후, 2SFCA 기반의 접근성 분석 과정에서 매개 변수값 선택을 위한 신중한 시나리오 적용이 필요할 것이다.

• Environmental Analysis Health and Toxicology
• /
• 제22권2호통권57호
• /
• pp.111-118
• /
• 2007

This study was performed to measure gaseous Organochlorine Pesticides (OCPs : heptachlor epoxide, ${\alpha}/{\gamma}-chlordane$, trans-nonachlor, endosulfan, ${\gamma}-HCH$ and p, p'-DDE) concentration using PUF high volume sampler from June, 2000 to June, 2002 in the semi-rural atmosphere. Using monitoring data for two years, we tried to investigate the annual cycles of gaseous OCPs. We considered three functions to describe the annual cycle: Gaussian, Lorentzian and sinusoidal functions. These functions accounted for $54{\sim}91%$ of the variability in concentration for each gaseous OCPs, and the sinusoidal function gave the best fits. It was seen that the gaseous OCPs concentration increased during the warmer weather while decreased during colder weather. The variation of the gaseous OCPs concentration was closely similar to the variations of ambient temperature. The annual cycle of endosulfan was strongly higher than in comparison with other gaseous OCPs, while for ${\gamma}-HCH$, the cycle was weakly high and did not show apparent seasonal variation. The position of the annual maximum exists generally late July to early August. The period that showed levels more than a half maximum was from late June to early September.

• 천문학회지
• /
• 제36권spc1호
• /
• pp.93-99
• /
• 2003

Various attempts have been made to explain the: pronounced seasonal and universal time (UT) variations of geomagnetic indices. As one of such attempts, we analyze the hourly-averaged auroral electroject indices obtained during the past 20 years. The AU and AL indices maximize during summer and equinoctial months, respectively. By normalizing the contribution of the solar conductivity enhancement to the AU index, or to the eastward electrojet, it is found that the AU also follows the same semiannual variation pattern of the AL index, suggesting that the electric field is the main modulator of the semiannual magnetic variation. The fact that the variation pattern of the yearly-mean AU index follows the mirror image of the AL index provides another indication that the electric field is the main modulator of magnetic disturbance. The pronounced UT variations of the auroral electrojet indices are also noted. To determine the magnetic activity dependence, the probability of recording a given activity level of AU and AL during each UT is examined. The UT variation of the AL index, thus obtained, shows a maximum at around 1200-1800 UT and a minimum around 0000-0800 UT particularly during winter. It is closely associated with the rotation of the geomagnetic pole around the rotational axis, which results in the change of the solar-originated ionospheric conductivity distribution over the polar region. On the other hand the UT variation is prominent during disturbed periods, indicating that the latitudinal mismatch between the AE stations and the auroral electrojet belt is responsible for it. Although not as prominent as the AL index, the probability distribution of the AU also shows two UT peaks. We confirm that the Dst index shows more prominent seasonal variation than the AE indices. However, the UT variation of the Dst index is only noticeable during the main phase of a magnetic storm. It is a combined result of the uneven distribution of the Dst stations and frequent developments of the partial ring current and substorm wedge current preferentially during the main phase.