• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1845-1848
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• 2005

The automatic $CO_2$ welding is a manufacturing process to produce high quality joints for metal and it could provide a capability of full automation to enhance productivity. Despite the widespread use in the various manufacturing industries, the full automation of the robotic $CO_2$ welding has not yet been achieved partly because the mathematical model for the process parameters of a given welding task is not fully understood and quantified. Several mathematical models to control welding quality, productivity, microstructure and weld properties in arc welding processes have been studied. However, it is not an easy task to apply them to the various practical situations because the relationship between the process parameters and the bead geometry is non-linear and also they are usually dependent on the specific experimental results. Practically, it is difficult, but important to know how to establish a mathematical model that can predict the result of the actual welding process and how to select the optimum welding condition under a certain constraint. In this research, an attempt has been made to develop an intelligent algorithm to predict the weld geometry (top-bead width, top-bead height, back-bead width and back-bead height) as a function of key process parameters in the robotic $CO_2$welding. A sensitivity analysis has been conducted and compared the relative impact of three process parameters on bead geometry in order to verify the measurement errors on the values of the uncertainty in estimated parameters.

• 대한방사선기술학회지:방사선기술과학
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• 제38권2호
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• pp.89-99
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• 2015

본 연구는 광자 신호의 검출 효율에 따른 collimator의 특성과 폐기능 정량분석의 상관관계를 비교하여 고감도 collimator 폐 환기 SPECT의 임상적용 가능성을 평가하였다. 2014년 3월부터 5월까지 10명의 정상 성인을 대상으로 초고해상도, 고해상도, 고감도 3종류의 collimator를 이용하여 평면 스캔과 SPECT를 비교 실험하였다. 기존 검사방법인 고해상도 collimator 평면 스캔과 비교하여 정량분석 결과는 유의하였으며(p=0.89), 고해상도 collimator SPECT보다 4.9배의 시간이 단축되었다. 따라서 효용성 저하로 제한적으로 시행하였던 폐 환기 SPECT는 고감도 collimator를 이용하면 진단 정보의 양과 질, 검사시간의 단축 측면에서 효과적이므로 추후 임상적용에 유용할 것으로 사료된다.

• 정보보호학회논문지
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• 제30권4호
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• pp.537-544
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• 2020

악성코드 기술 발전으로 변이, 난독화 등의 탐지 회피 방법이 고도화되고 있다. 이에 악성코드 탐지 기술에 있어 알려지지 않은 악성코드 탐지 기술이 중요하며, 배포된 악성코드를 통해 저자를 식별하여 알려지지 않은 악성코드를 탐지하는 악성코드 저자 식별 방법이 연구되고 있다. 본 논문에서는 바이너리 기반 저자 식별 방법에 대해 중요 정보인 컴파일러 정보를 추출하고자 하였으며, 연구 간에 특징 선택, 확률 및 비확률 모델, 최적화가 분류 효율성에 미치는 민감성(Sensitive)을 확인하고자 하였다. 실험에서 정보 이득을 통한 특징 선택 방법과 비확률 모델인 서포트 벡터 머신이 높은 효율성을 보였다. 최적화 연구 간에 제안하는 프레임워크를 통한 특징 선택 및 모델 최적화를 통해 높은 분류 정확도를 얻었으며, 최대 48%의 특징 감소 및 51배가량의 빠른 실행 속도라는 결과를 보였다. 본 연구를 통해 특징 선택 및 모델 최적화 방법이 분류 효율성에 미치는 민감성에 대해 확인할 수 있었다.

• 한국정보통신학회논문지
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• 제10권10호
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• pp.1796-1803
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• 2006

본 연구에서는 비선형성이 강한 대표적인 불안정한 시스템으로 새로운 제어 이론의 유효성을 실증하고 평가하기에 적합한 도립 진자 시스템의 강인 안정 및 강인 제어 성능을 확보하기 위하여 $H_{\infty}$ 제어 이론을 도입하여 최적 제어기를 설계하였다. 그리고, 저역통과 필터를 제어 대상 시스템과 종속으로 결합시켜 개루프 전달함수의 형성(loop shaping)을 시도함으로서, 감도함수 및 상보감도함수가 바람직 한 주파수 특성을 갖도록 하였다. 먼저, 설계한 $H_{\infty}$제어기를 도립진자 제어시스템에 적용하여 시뮬레이션 하였고, 그 결과를 전통적인 기법으로 산업현장에서 널리 사용하고 있는 PID제어기를 채용한 시스템의 출력과 비교하여 그 가능성을 확인하였다. 그런 다음, 설계 한 제어기를 실제 시스템에 적용하여 실험하였다. 시뮬레이션 및 실험 결과를 통해, $H_{\infty}$ 제어기는 모델링 오차, 외란 및 노이즈의 영향을 줄이면서 제어목표를 잘 추종하는 것으로 나타나 안정도 및 제어성능이 우수함을 확인할 수 있었다.

• 대한미생물학회지
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• 제9권1호
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• pp.25-31
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• 1974

A comparative study was performed with 176 cultures of Salmonella organisms on tetracyline, neomycin and colistin in order to find out the relationship between the results obtained from the Ericsson's single disk method and the tube dilution method of antibiotic sensitivity tests which may be carried out in many hospital laboratories. With tetracycline, thirty-three out of 163 cultures of Salmonella typhi were found to be either sensitive or moderate sensitive by means of the disk method and thirty one(ca 94%) out of the thirty three cultures showed less than 1.0 ${\mu}g$ of the Minimal Inhibitory Concentretions(MIC) in the tube-dilution tests, which mean that there were a quite good agreement between the two methods. With neomycin, a hundred and five out of 163 S.typhi were appeared to be either sensitive or moderate sensitive by means of Ericsson's single disk method, among which 103 cultures showed less than 10.0 ${\mu}g$ MIC in the tubedilution method. And also there was a quite correlative pat. terns observed in the result of testing with 13 salmonella cultures other than S. typhi. With colistin, it was hard to observe any particular tendency in the distribution of plotting for 148 cultures showing less the 18 mm in the inhibiting zone diameters between MIC and disk sensitivity patterns except the fifteen, cultures out of 176 salmonella, which appeared to be sensitive in the single disk method and showed less than 1.0 ${\mu}g$ MIC in the tube dilution method.

• Asian Journal of Atmospheric Environment
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• 제4권3호
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• pp.198-210
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• 2010

Precise analysis of local winds for the prediction of atmospheric phenomena in the planetary boundary layer is extremely important. In this study, wind profiler data with fine time resolution and density in the lower troposphere were used to improve the performance of a numerical atmospheric model of a complex coastal area. Three-dimensional variational data assimilation (3DVAR) was used to assimilate profiler data. Two experiments were conducted to determine the effects of the profiler data on model results. First, we performed an observing system experiment. Second, we implemented a sensitivity test of data assimilation intervals to extend the advantages of the profiler to data assimilation. The lowest errors were observed when using both radio sonde and profiler data to interpret vertical and surface observation data. The sensitivity to the assimilation interval differed according to the synoptic conditions when the focus was on the surface results. The sensitivity to the weak synoptic effect was much larger than to the strong synoptic effect. The hourly-assimilated case showed the lowest root mean square error (RMSE, 1.62 m/s) and highest index of agreement (IOA, 0.82) under weak synoptic conditions, whereas the statistics in the 1, 3, and 6 hourly-assimilated cases were similar under strong synoptic conditions. This indicates that the profiler data better represent complex local circulation in the model with high time and vertical resolution, particularly when the synoptic effect is weak.

• 한국멀티미디어학회논문지
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• 제15권3호
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• pp.364-371
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• 2012

중국의 디지털 모바일 방송 표준인 CMMB (China Mobile Multimedia Broadcasting)는 기존의 지상파 TV 방송인 Analog 방송과 동일한 주파수 대역 (474MHz ~ 754MHz)을 통해 송출되고 있다. 또한 기존의 Analog 방송의 수신 품질을 위해 디지털 방송의 송출 전력을 기존의 Analog 방송보다 낮게 하여 송출한다. 이러한 현상으로 인해 CMMB 수신기는 CMMB 수신신호와 인접하는 대역에 존재하는 Analog 방송 신호 영향을 받게 된다. 또한 셀의 경계에 있는 지역에서 CMMB 채널이 서로 인접해 있을 경우 수신기는 원하는 CMMB 신호 수신에 영향을 받게 된다. 이러한 인접 채널 간섭 (ACI : Adjacent Channel Interference)으로 인해CMMB 수신 성능에 영향을 미치며 이는 CMMB 수신기의 품질이 저하되는 문제로 이어지게 된다. 본 논문에서는 이러한 인접 채널 간섭현상을 간단하게 제거하기 위해 저주파 대역 통과 필터 (LPF : Low Pass Filter)의 차단 주파수를 조정하여 인접 채널에 의한 간섭을 최소화하였으며 이를 통해 CMMB 수신기의 수신 성능이 11.3dB 향상됨을 실험을 통해 알 수 있었다.

• 한국대기환경학회지
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• 제34권5호
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• pp.708-726
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• 2018

In this study, we examined the contribution of nitrogen oxides and volatile organic compounds emitted from China and Japan to ozone concentrations over Gwangyang-bay, South Korea. We used a chemical transport model, Community Multi-scale Air Quality model, and its instrumented sensitivity tool, High-order Decoupled Direct Method. Intercontinental Chemical Transport Experiment-Phase B 2006 for East Asia and Clean Air Policy Support System 2007 emissions inventories for South Korea were used for the ozone simulation. During the study period, May 2007, the modeled maximum daily 8-hr average ozone concentration among seven air quality monitors in Gwangyang-bay was 68.8 ppb. The contribution of $NO_x$ emissions from China was 19.5 ppb (28%). The highest modeled ozone concentrations and Chinese contributions appeared when air parcels were originated from Shanghai area. The observed 8-hr average ozone concentrations in Gwangyang Bay exceeded the national ambient air quality standard (60 ppb) 203 times by daytime and 56 times by nighttime during the period. It was noticed that many exeedances happened when contribution of Chinese emissions to ozone concentrations over the area increased. Sensitivity analysis shows that a reduction in Chinese $NO_x$ and VOC emissions by 15% could lessen the total exceedance hours by 24%. This result indicates that high ozone concentrations over Gwangyang-bay are strongly enhanced by Chinese emissions.

• Journal of Nutrition and Health
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• 제39권4호
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• pp.323-330
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• 2006

Peripheral insulin resistance in obese/type II diabetes animals results from an impairment of insulin-stimulated glucose uptake into skeletal muscle. Insulin stimulate the translocation of GLUT4 from intracellular location to the plasma membrane. Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) is implicated in mediation of fusion of GLUT4-containing vesicle with the plasma membrane. Present study investigated regulatory effects of Rhodiola sachalinensis administration and exercise training on the expression of GLUT4 protein and SNAREs protein in skeletal muscles of obese Zucker rats. Experimental animals were randomly assigned into one of five groups ; lean control(LN), obese control(OB), exercise-treated(EXE), Rhodiola sachalinensis-treated(Rho), combine of Rho & EXE (Rho-EXE). All animals of exercise training (EXE, Rho-EXE) performed treadmill running for 8 weeks, and animals of Rho groups (Rho, Rho-EXE) were dosed daily by gastric gavage during the same period. After experiment, blood were taken for analyses of glucose, insulin, and lipids levels. Mitochondrial oxidative enzyme (citrate synthase, CS ; $\beta$-hydroxyacyl-CoA dehydrogenase, $\beta$-HAD) activity were analysed. Skeletal muscles were dissected out for analyses of proteins (GLUT4, VAMP2, syntaxin4, SNAP23). Results are as follows. Exercise and/or Rhodiola sachalinensis administration significantly reduced body weight and improved blood lipids (TG, FFA), and increased insulin sensitivity. Endurance exercise significantly increased the activity of mitochondrial enzymes and the expression of GLUT4 protein, however, administration of Rhodiola sachalinensis did not affect them. The effect of exercise and/or Rhodiola sachalinensis administration on the expression of SNARE proteins was unclear. Our study suggested that improvement insulin sensitivity by exercise and/or Rhodiola sachalinensis administration in obese Zucker rats is independent of expression of SNARE proteins.

• 동력기계공학회지
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• 제15권2호
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• pp.13-18
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• 2011

This thesis is about the result of conducting a specific experiment for the development of noncontact vibration displacement sensor for measuring the spindle vibration that is used for conditional monitoring of machinery. One should be careful when using the eddy current type displacement sensor because the sensitivity of it is different according to the quality of the material. While the probe used for nondestructive inspection adopts the effect of transmitting the material by using the high frequency domain, the eddy current type displacement sensor uses the lower frequency of around 1MHz. Also, while the nondestructive probe uses the method of enhancing output by using the resonance zone, the vibration displacement sensor utilizes the stable zone by avoiding the resonance zone. Since the oscillator of the converter uses the "L" element as Probe, its characteristic changes with the variation of a relevant impedance. In other words, if the length of Probe's Cable gets extended (Impedance increase), the sensitivity declines accordingly. The effect of surrounding temperature was small, but the influence of the quality of Sensor Coil used was high. Moreover, following an experimental demonstration of the phenomenon where the sensitivity decreases as the frequency of the tested material increases from a frequency response test, the maximum frequency that could be measured was approximately 1KHz. It was noted that the degree of precision could be maintained by using the gap of the probe in the linear zone at the installation site.