• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1612-1614
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• 2004

The piezoelectric ceramics for AE-sensor are desired large electromechanical coupling factor, high mechanical quality factor and good characteristic resonance frequency. In this study, the empirical formula of specimens is used 0.9Pb$(Zr_xTi_{1-x})O_3-0.1Pb(Mn_{1/3}Nb_{1/3}Sb_{1/3})O_3$ (PZT-PMNS). The piezoelectric and dielectric characteristic are investigated by sintering temperature and value of x as functions of $Ti^{2+},\;Zi^{2+}$ moi rate. MPB(morphotropic phase boundary) is defned in the x=0.522. Because it is appeared to the best piezoelectric and dielectric characteristic in the x=0.522, it can be application of AE sensor. PZT-PMNS ceramics without pre-amplifier and filter are tested for AE-signal of PD and arc detecting. The detection characteristic is evaluated wave form, frequency distribution.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.288-297
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• 1994

The sewing machine is one of the oldest machine that has ever used, which is related with clothes' life. Modern sewing machines are divided into three groups by the sititch character, which are the lock stitch sewing machine group, the over lock sewing machine group and the specical sewing machine group. The lock stitch sewing machine have being used more than any others, which is also good model to study. This work is part of the improvement of an industrial lock stitch(ILS) sewing machine's design. The research objectives are the kinematic analysis and evaluations of stitch performance. The feed dog and the needle extreme's motion, which are important two part's motion in the sewing machine, are characterized by the stitch process and the needle trace. The needle trace is formulated as the stitch spacing, the stitch spacing's ratio(the static characteristic), and the stitch's phase difference(the dynamic characteristic). The tested ILS sewing machine is evaluated as a good static characteristic and a bad dynamic characteristic. Namely, a stitch spacing's ratio is 0.01~0.063(mm/mm) and a stitch's phase difference ratio is 0.06~0.13(mm/mm).

• 한국신뢰성학회지:신뢰성응용연구
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• 제1권2호
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• pp.121-138
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• 2001

Due to large demand for high speed and great capacity for data transfer, WDM, which uses the wavelength division multiplexing technique, is known as alternative way to satisfy those demand for its flexible network operation and management, easy network expansion with existing networks, and enhancement of efficient data transfer rate. For these reasons, a new high capacity WDM optical communication network plan was established. Therefore, the quality of currently deployed optical cables with 81.6 km in length should be assessed to ensure if high capacity WDM system could be implemented on existing optical cables. Two important characteristic parameters, Transfer Loss and PMD (Polarization Mode Dispersion), were measured to evaluate quality of existing optical cable. Transfer Loss was measured at 0.244 dB per kilometer, which is lower than the design standard value at 0.275 dB/km. The measured PMD value gave at 0.030ps/km, and it, therefore, satisfies the value recommended by ITU-T (International Telecommunication Union-T) of 0.5ps/km. In addition, the transfer characteristic for existing 2.5 Gbps and 10 Gbps system were measured and evaluated, and the results showed that error-free transfer is very much feasible. Computer simulation for DWDM system, which is likely be a future backbone network in Korea, to assess the transfer characteristic using the same condition employed for 2.5 Gbps and 10 Gbps was carried out as well. The simulation verified that a stable network operation and reliable service could be provided.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.515-518
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• 2004

The Piezoelectric ceramics for AE(Acoustic Emission) sensor are desired large electromechanical coupling factor, high mechanical quality factor and good characteristic resonance frequency. In this study, the empirical formula of specimens is used $0.9Pb(Zr_xTi_{1-x})O_3-0.1Pb(Mn_{1/3}Nb_{1/3}Sb_{1/3})O_3$ (PZT-PMNS). The piezoelectric and dielectric characteristic are investigated by sintering temperature and value of x as functions of $Ti^{2+},\;Zi^{2+}$ mol rate. MPB(morphotropic Phase boundary) is defined in the x=0.522. Because it is appeared to the best piezoelectric and dielectric characteristic in the x=0.522, it can be application by AE sensor. PZT-PMNS ceramics without pre-amplifier and filter are tested for detecting of arc signal. The detection characteristic is evaluated wave form, frequency distribution.

• 한국식품과학회지
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• 제33권2호
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• pp.195-199
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• 2001

Amylograph를 이용하여 방사선 조사된 검은후추가루의 amylograph characteristics의 변화를 검사하고, 변화된 amylograph characteristics에 의해서 검은후추가루의 검지가 가능한지를 알아보기 위하여 본 실험은 수행되었다. Initial pasting temperatures, maximum viscosity temperatures는 조사선량의 증가에 따른 유의적인 변화가 관찰되지 않았다. Maximum viscosity(P), $93^{\circ}C$ viscosity, $93^{\circ}C$에서 15분 후의 viscosity(H), $45^{\circ}C$ viscosity(C), $45^{\circ}C$에서 30분 후의 viscosity, $45^{\circ}C$에서 60분 후의 viscosity는 조사선량이 증가할수록 감소하는 경향을 보여주었으며, p<0.05의 수준에서 통계적인 유의성이 관찰되었다. 그러나 breakdown(P-H), setback(C-P), 그리고 consistency(C-H)는 조사선량의 증가에 따른 명확한 차이가 관찰되지 않았다. breakdown(P-H)이 0.75, setback(C-P)이 0.88, consistency(C-H)가 0.31의 $R^2$ 값을 보인 것을 제외하고는 모든 amylograph characteristics 의 $R^2$ 값은 0.97 이상의 높은 상관성을 보여 주었다. 따라서 amylograph characteristics에 의해서 검은후추가루의 방사선 조사여부 확인이 가능하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.236-239
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• 1999

This paper is the study for electrical characteristic of PZT ceramics with Sb$_2$O$_3$, CoO additive. Effect of Sb$_2$O$_3$, CoO additive ranged from 0.0 wt% to 1.2wt% on the electrical characteristic of the PZT ceramics have been investigated. In the case of Sb$_2$O$_3$ 0.6wt%, the maximum vague of mechanical quality factor(Qm) was obtained 124.11 at l15$0^{\circ}C$. And, additive CoO 1.2wt% was obtained 184.12 at l15$0^{\circ}C$. The electromechanical coupling factor(kp) was increased by increasing the amount of Sb$_2$O$_3$, CoO additive. The maximum value of electromechanical coupling factor(kp) was obtained 58.35 with Sb$_2$O$_3$1.2wt% additive at l15$0^{\circ}C$. Dopped with additive CoO 0.9wt%, electromechanical coupling factor(kp) was obtained 47.84 at 115$0^{\circ}C$.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권6호
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• pp.118-129
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• 2021

The sediment transportation caused by soil erosion due to rainfall-discharge in the large watershed scale plays critical role in human society. The relationship between rainfall-discharge-sediment transportation is depending on the start time of rainfall and end of rainfall but, the studies related with rainfall characteristics are insufficient. In this study, The Soil and Water Assession Tool (SWAT) model was used to study the relationship between rainfall-discharge-sediment transportation at the Sook river watershed which is monitored by the Ministry of Environment. To do this, first of all, the sensitivity analysis about model attributes was performed using monitored data. The accuracy analysis of SWAT model was conducted using the model's efficiency index (Nash and Sutcliffe model efficiency; NSE) and the coefficient of determination (R²). After that, it was studied what results could be obtained according to changes in rainfall timing and end points. In the result of discharge simulation, the modified rainfall values (sum of total rainfall starting time and end time) showed more high accuracy values (R²:0.90, NSE: 0.8) than original rainfall values (R²:0.76, NSE: 0.72). In the result of sediment transportation simulation, during calibration had more resonable results(R²:0.87, NSE: 0.86) than compared with original rainfall values (R²:0.44, NSE: 0.41). However, validation results of sediment transportation simulation showed low accuracy values compared with calibration results. This results maybe cause monitoring periods of sediment flow compared with discharge monitoring periods. Nevertheless, since rainfall characteristic plays critical rule in model results, continuous research on rainfall characteristic is needed.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.315-319
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• 2010

The near wake of square section cylinders with different corner radii is studied by numerical method to investigate the influence of corner radius. Eight models, R/D=0, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5 (R is the corner radius and D is the characteristic dimension of the body) at Re=500 were studied. The numerical results of St, CD and CL at R/D=0 and R/D=0.5 were compared with experiments to prove the feasibility and also investigate the trend of flow phenomena by the various radius corners. Results indicate that, as R/D ratio is increased, the Strouha lnumber is increased, the minimum pressure point on the cylinder surface moved own stream. The calculated results shows that between R/D=0.15 to R/D=0.3 have CD and CL.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 추계학술대회 논문집
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• pp.164-167
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• 1994

In this Study, we design the process of 0.1$\mu\textrm{m}$ gate length CMOS that is immunized against Latch-up, and investigate the characteristic of Latch-up of this device by the design rule of layout. Using TSUPREM4 and MEDICI, we design the device and simulate the variable characteristics of it we could understand that the characteristic of Latch-up is changed for the better by varying the critical factor of it. We also investigate the structure of CMOS that can be immunized against Latch-up.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.198-204
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• 2004

액화천연가스를 연료로 사용하여 물 냉각 및 천연가스와 액화천연가스 재생냉각 연소시험을 수행하였다. 연소시험과 CEC86을 이용한 연소해석 결과를 액체로켓엔진 성능인자로서, 특성속도와 비추력 관점에서, 추진제 혼합비와 연료의 연소실 유입온도의 영향을 분석하였으며, 엔진성능이 추진제 혼합비와 연료의 연소실 유입온도의 영향을 크게 받고 있음을 알 수 있었다. 엔진 성능으로서 특성속도는 추진제 혼합비가 0.72∼0.75일 때, 이론적 비추력은 추진제 혼합비가 0.75일 때 최대 값을 보여주었으며, 연료의 연소실 유입온도의 증가에 비례하여 엔진 성능이 향상되는 경향에서 재생냉각이 엔진 성능을 증대시키는 경향을 확인하였다.