• Korean Membrane Journal
• /
• 제6권1호
• /
• pp.37-43
• /
• 2004

Comb-type graft hydrogels composed of alginate and poly(N-isopropylacrylamide) (PNIPAAm) were prepared to manifest rapid temperature and pH sensitivity. To appear the electro-sensitivity, the polyaniline, conducting polymer, was added into the matrix. The swelling kinetics and ratios were compared under the various compositions of polyaniline. The swelling behaviors revealed that conducting polymer/hydrogel composites could control the swelling ratio and kinetics. The addition of polyaniline in the matrix improved the thermal stability in comparison with that of the hydrogel without polyaniline. In temperature sensitivity, the adding the polyaniline into the matrix decreased the degree of change in the swelling ratio. The swelling ratios continuously increased with increasing pH values. The drug release rate from the hydrogel increased with the adding the polyaniline and the applying the direct voltage to the hydrogels.

• Nuclear Engineering and Technology
• /
• 제33권6호
• /
• pp.605-618
• /
• 2001

For the mechanical stability assessment of a deep underground high-level waste repository. computer simulations using FLAC3D were carried out and important parameters including stress ratio, depth, tunnel size, joint spacing, and joint properties were chosen from sensitivity analysis. The main effect as well as the interaction effect between the important parameters could be investigated effectively using fractional factorial design . In order to analyze the stability of the disposal tunnel and deposition hole in a discontinuous rock mass, different modelings were performed under different conditions using 3DEC and the influence of joint distribution and properties, rock properties and stress ratio could be determined. From the three dimensional modelings, it was concluded that the conceptual repository design was mechanically stable even in a discontinuous rock mass.

• 항공우주기술
• /
• 제12권1호
• /
• pp.200-206
• /
• 2013

액체로켓엔진에서 추진제 밀도와 공급 압력 변화에 대한 성능 민감도를 분석하였다. 해석 프로그램은 터보펌프-가스발생기 연계시험 결과와 비교하여 1% 오차를 가지는 것으로 확인되었다. 연료 공급압력이 증가하면 혼합비 감소로 인해 엔진 연소압이 감소하였고 연료의 밀도가 증가하면 혼합비 감소에도 불구하고 추진제 유량이 증가하므로 엔진 연소압이 증가하는 것으로 예측되었다. 또한 산화제의 밀도가 증가되거나 공급압력이 증가하면 엔진의 연소압이 증가할 것으로 분석되었다.

• Journal of Industrial and Engineering Chemistry
• /
• 제67권
• /
• pp.236-243
• /
• 2018

A series of $Er^{3+}/Yb^{3+}$ co-doped fluorophosphate glasses with varying $YbF_3$ concentration were prepared by a high temperature melt quenching technique. Absorption and emission cross-sections were determined by using the McCumber theory. The larger emission cross-section ($9.86{\times}10^{-21}cm^2$) and longer fluorescence lifetime (12.37 ms) were obtained for the $^4I_{13/2}{\rightarrow}^4I_{15/2}$ transition of ABS3Er4Yb glass. The sensitivity and temperature of the maximum sensitivity were evaluated by the fluorescence intensity ratio method from the measured upconversion spectra. The results were discussed and compared to the other reported glasses.

• 한국안전학회지
• /
• 제12권2호
• /
• pp.17-21
• /
• 1997

The fatigue crack propagation rate has so far been measured by the effective stress intensity factor range Δ K/sub eff/. But no research has been done to study how much the crack opening ratio influences the expectation of the fatigue crack propagation. Therefore, this paper evaluates of the crack opening ratio on the fatigue crack propagation life by using the method of parameter sensitivity study. Summarizing the result ; ( 1 ) When the crack opening ratio U' is high, the effect of U' gets larger than any other except for the material factor m. But when U' is low, the effect is also diminished. Therefore, the selection of the lowest value possible is desirable in the evaluation of life. (2) When the value of the material factor m is high, the effect of crack opening ratio U' is increased, at the same time the effect of the other parameters also increased wholly. The effect of material factor m itself on life is high, but in case the material factor m is high, that the effect of each parameter on life get higher is unique. In designing, better attention to the material selection should be drawn. (3) In case the stress ratio R gets smaller, the effect of crack opening ratio U' is unchangeable. But the effect of R itself remarkably decreases, and the effect of material factor m somewhat decreases.

• 센서학회지
• /
• 제31권1호
• /
• pp.1-5
• /
• 2022

In this paper, the photocurrent characteristics of gate/body-tied (GBT) metal-oxide semiconductor field-effect transistor (MOSFET)-type photodetector with high sensitivity in the 408 nm - 941 nm range are presented. High sensitivity is important for photodetectors, which are used in several scientific and industrial applications. Owing to its inherent amplifying characteristics, the GBT MOSFET-type photodetector exhibits high sensitivity. The presented GBT MOSFET-type photodetector was designed and fabricated via a standard 0.18 ㎛ complementary metal-oxide-semiconductor (CMOS) process, and its characteristics were analyzed. The photodetector was analyzed with respect to its width to length (W/L) ratio, bias voltage, and incident-light wavelength. It was confirmed experimentally that the presented GBT MOSFET-type photodetector has over 100 times higher sensitivity than a PN-junction photodiode with the same area in the 408 nm - 941 nm range.

• Clinical and Experimental Pediatrics
• /
• 제48권8호
• /
• pp.857-864
• /
• 2005

목 적 : 인슐린 감수성 지표들은 신체계측지수인 체질량지수 및 비만도와 상관관계를 보이는 것으로 알려져 있다. 그러나 이러한 신체계측지수들이 체지방량을 잘 반영하는 것으로 알려져 있기는 하나 소아에서는 성인에 비해 그 정확도가 떨어지므로 실제로 측정한 체지방량과 인슐린 감수성 지표들 간에도 이와 같은 연관성이 있는지에 대한 연구는 없는 실정이다. 따라서 본 연구에서는 단순 소아 비만아들을 대상으로 하여, 체지방측정에 있어 비교적 객관적이며 정확한 방법으로 알려진 BIA와 DEXA로 측정한 체지방량과 인슐린 감수성 지표들 간에 어떠한 연관성이 있는지 알아보고 추후 외래에서 비만아들을 추적 관찰할 때 어느 지표가 가장 유용한지 알아보고자 한다. 방 법 : 2002년 1월부터 2004년 7월까지 중앙대학교 용산병원 비만클리닉을 방문한 28명의 단순비만 환자를 대상으로 하였다. 12시간 이상 금식 후 채혈을 하여 혈당과 인슐린 수치를 측정하였다. 같은 날 신장, 체중, 허리 둘레, 엉덩이 둘레를 계측하였고, BIA와 DEXA를 시행하여 체지방량을 구하였다. 얻어진 혈당과 인슐린 수치를 이용하여 G/I ratio, $log_{insulin}$, HOMA-IR, $log_{HOMA-IR}$, QUICKI를 구하여 체지방량과의 연관성을 알아보았다. 결 과 : 1) 인슐린 감수성 지표 중 G/I ratio만 triglyceride와 통계상 연관성이 있는 것으로 나왔다(r=-0.206, P<0.05). 이외의 $log_{insulin}$, HOMA-IR, $log_{HOMA-IR}$, QUICKI는 혈중 지질치와 관련이 없었다. 2) 비만도는 G/I ratio와 -0.209(P<0.05), $log_{insulin}$과 0.196(P<0.05), HOMA-IR과 0.238(P<0.01), $log_{HOMA-IR}$과 0.198(P<0.05), QUICKI와는 -0.224(P<0.05)로 연관성이 있는 것으로 나왔고, 체질량지수는 G/I ratio와 -0.463(P<0.01), $log_{insulin}$과 0.417(P<0.05), HOMA-IR과 0.301(P<0.01), $log_{HOMA-IR}$과 0.403(P<0.01), QUICKI와는 -0.451(P<0.01)로 나와 비만도 보다 더 인슐린 감수성 지표들과 상관성이 높은 것으로 나타났다. 3) BIA로 측정한 체지방량과 비만도 및 체질량지수 각각에 대한 상관계수는 0.612(P<0.01), 0.316(P<0.05)으로 나왔고, DEXA로 측정한 체지방량과는 각각 0.667(P<0.01), 0.512(P<0.05)로 나와 체지방량과 비만도 및 체질량지수 사이에 연관성이 있는 것으로 밝혀졌다. 4) G/I ratio는 BIA로 측정한 체지방량 및 체지방률과 각각 상관계수 -0.420(P<0.05), -0.366(P<0.05)으로 상관성을 보이고 있었고, DEXA로 측정한 체지방량 및 체지방률과도 -0.512(P<0.01), -0.449(P<0.01)로 높은 상관성을 보였다. HOMA-IR은 DEXA로 측정한 체지방량과만 상관계수 0.341(P<0.05)로 연관성을 나타냈고, 그밖에 다른 인슐린 감수성 지표들은 체지방량 및 체지방률 모두와 상관성이 없었다. 결 론 : 인슐린 감수성 지표들과 비만도 및 체질량지수와 같은 신체 계측지수들 간의 상관성에서, 인슐린 감수성 지표 특히 G/I ratio가 비만도 및 체질량지수 모두와 높은 상관성을 보였고, 체지방량 및 체지방률과 인슐린 감수성 지표와의 관계에서는 G/I ratio만이 BIA와 DEXA로 측정한 체지방량과 체지방률 모두와 연관성이 있는 것으로 나타났다. 따라서 단순 비만아의 진단 및 추적 관찰시 BMI 및 인슐린과 혈당치를 기초로 한 인슐린 감수성 지표 특히, G/I ratio의 활용이 임상에서 유용하게 사용될 수 있을 것으로 생각된다.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1998년도 제27회 춘계학술대회
• /
• pp.124-130
• /
• 1998

A mathematical model describing gear pump flow degradation in the presense of abrasive particles is presented. The model considers the operating parameters as Sommerfeld number, so that contamination sensitivity test results could be conversed to field application to predict contamination service life. A method to estimate the volumetric efficiency and the contamination level of a pump is proposed by measuring the temperature differences in the fluid. Test results show the validity of the theoretical establishments.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2015년도 제46회 하계학술대회
• /
• pp.1241-1242
• /
• 2015

이 연구는 정전용량형 압력센서 내의 공기가 센서 성능에 미치는 영향을 줄이고자 이론적 접근과 실험적 확인을 통해 제안된 바 있는 센서 모델을, 유한요소해석 프로그램인 ANSYS로 각각의 조건에 따라 해석하여 기존에 제시 된 결과들과 비교하는 과정을 다루었다. FEA(Finite Element Analysis)결과, air chamber를 추가한 센서는 기존의 센서보다 sensitivity가 향상되었음을 확인할 수 있었다. 또한, FEA로 얻은 sensitivity 값은 이론값과 1.8%~10.1%의 차이를 보였으며, sensitivity ratio는 이론값과 실험값의 중간 정도로 나타났다.

• 대한기계학회논문집B
• /
• 제28권2호
• /
• pp.207-214
• /
• 2004

The burning velocities of conventional and oxygen-enriched methane flame in various equivalence ratio were determined by experiments. The validity of existing reaction mechanisms was examined in oxygen-enriched flame on the basis of the experiment results. Modified reaction mechanism is suggested, which was able to predict burning velocity of oxygen enriched flame as well as methane-air flame. Complementary study on reaction mechanisms shows the following results : Present experiment data were found to be more reliable in comparison with existing ones in a oxygen-enrichment condition. It was found that some modification in existing reaction mechanisms is necessary, since discrepancy between measurements and predictions is increasing with oxygen enrichment ratio. The sensitivity analysis was performed to discriminate the dominantly affecting reactions on the burning velocity in various oxygen enrichment and equivalence ratio. A modified GRI 3.0 reaction mechanism based on our experiment results was suggested, in which reaction rate coefficients of (R38) H+O$_2$<=>O+OH in GRI 3.0 reaction mechanisms were corrected based on sensitivity analysis results. This mechanism showed a good agreement in predicting the burning velocity and number density of NO in oxygen-enriched flame and would provide proper reaction information of oxygen-enriched flame at this stage.