• 한국재료학회지
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• 제9권2호
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• pp.111-116
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• 1999

The microstructure of vitreous bonded abrasives, which are used as the essential materials in the precise grinding, was investigated theoretically using two particle model. In this paper, a general equation applicable for a case in which there is a gap between abrasive grits is suggested. As a result, it was known that both the volume ratio of grit to glassy bond(V\ulcorner/V\ulcorner) and porosity(V\ulcorner) are the function of $\alpha$(the ratio of distance between grit to diameter of grit) and $\theta$(the angle from the center of pore to that of grit). Because the value $\alpha$ and $\theta$ can be get easily by using these suggested equations, the microstructure could be explained quantitatively. Also the raised error with the increasing amount of bond was modified by the simple assumption. As a result, in that case, both V\ulcorner/V\ulcorner and V\ulcorner were known to be the function of $\alpha$ and $\theta$(the ratio diameter of pore to that of grit).

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.109-112
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• 2003

A method to determine As(V) ions in aqueous solution by chemiluminescence method has been studied using a stopped flow system. The method is based on the increased chemiluminescence intensity with the addition of As(V) ion to a solution of lucigenin and hydrogen peroxide. The effects of KOH concentration, $H_2O_2$ concentration and flow rate of reagents on the chemiluminescence intensity have been investigated. The calibration curve for As(V) was linear over the range from $1.0{\times}l0^{-6}$M to $1.0{\times}l0^{-4}$M, the coefficient of correlation was 0.997 and the detection limit was $3.3{\times}l0^{-7}$M under the optimal experimental conditions.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 1993년도 학술대회지
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• pp.206-214
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• 1993

Ginseng saponins have been known as main active principles and analyzed as the index components in ginseng and its products for quality control. But it is generally difficult to analyze the saponins in crude drug preparations. Saponins, Prosapogenins and sapogenins of crude drug preparation were identified by TLC and determined quantitatively by HPLC. $Prosapogemins-Rg_3\;-Rg_2\;and\;{\Delta}^{20}-prosapogenin$ were extracted with ethyl acetate from $50\%$ acetic acid hydrolyzates of saponin fractions and identified by TLC with lower phase of $CHCl_3/MeOH/H_2$ O\65:35:10. v/v)on silica gel plate, and quantified by HPLC on $Lichrosorb-NH_2$ column with $CH_3CN/H_2O(90:10,\;v/v).$ Sapogenins. panaxadiol and panaxatriol. were extracted with ethyl ether from $7\%-sulfuric$ acid hydrolyzates of saponin fractions and identified by TLC with chloroform/acetone(1 : 1 v/v) on silica gel plate. and quantified by HPLC on u - Bondapak $C^{18}$ column with $CH_3CN/MeOH/CHCl_3(83:10:7.\;v/v).$ These analyses of prosapogenins and sapogenins are more useful for quality control than those of saponins in crude drug preparations such as So - Shi - Ho - Tang(소시호탕), Sa - Kun - Ja - Tang(사군자탕), Yook - Kun - Ja - Tang(육군자탕), and In - Sam -Tang(인삼탕)

• 한국통신학회논문지
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• 제19권8호
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• pp.1571-1577
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• 1994

본 논문은 상향 주파수 변환에 의한 12GHz/14GHz의 주파수혼합기를 설계 구현하였다. 두 입력신호의 전력레벨 및 바이어스에 의한 고조파 및 상호변조 전력레벨의 변화를 고찰, 이를 이용하여 전력레벨의 상호변조(Intermodulation ratio : IMR)비를 얻어 구현된 주파수혼합기의 정확한 동작조건을 보였다. 결과적으로 얻은 최적의 동작조건은 신호의 전력레벨이 -30[dBm]이하이며, 국부발진 전력레벨은 -2[dBm]이하였다. 그때의 바이어스 조건은 $V_{DS}$ 가 2.7[V]이며, $V_{GS}$는 -0.2[V]였다.

• 자동차안전학회지
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• 제14권3호
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• pp.48-59
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• 2022

A V2X system can be a candidate as a means to increase the stability of autonomous vehicles. In particular, in order to implement a Level 4 or higher autonomous driving system, the application of the V2X system is essential. Wireless communication technologies applicable to the V2X system include WAVE and C-V2X. Currently, the V2X service most used by autonomous driving systems is a service that provides signal phase and timing information and since real-time characteristic is a very important, verification of this service must be done. In this paper, we measured the time delay characteristics for providing signal phase and timing information using WAVE and LTE communication, and proposed a TOD-based signal phase and timing information generation method without using V2X communication system. To analyze the time delay characteristics, RTT (Round Trip Time) was measured as a result of the measurement. Average RTT using WAVE communication was 5.84ms and was 104.15ms with LTE communication. As a result of measuring the error between the signal phase and timing information generated based on TOD and the actual traffic light state, it was measured to be -0.284~3.784sec.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.618-625
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• 2021

In this paper, the single-photon avalanche diodes (SPADs) featuring three different p-well implantation doses (∅_p-well) of 5.0 × 10¹², 4.0 × 10¹², and 3.0 × 10¹² atoms/cm² under the identical device layouts were fabricated and characterized to evaluate the effects of field enhanced mechanisms on primary dark pulses due to the maximum electric field. From the I-V curves, the breakdown voltages were found as 23.2 V, 40.5 V, and 63.1 V with decreasing ∅_p-well, respectively. By measuring DCRs as a function of temperature, we found a reduction of approximately 8% in the maximum electric field lead to a nearly 72% decrease in the DCR at V_ex = 5 V and T = 25 ℃. Also, the activation energy increased from 0.43 eV to 0.50 eV, as decreasing the maximum electric field. Finally, we discuss the importance of electric field engineering in reducing the field-enhanced mechanisms contributing to the DCR in SPADs and the benefits on the SPADs related to different types of radiation detection applications.

• 대한전자공학회논문지SD
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• 제40권1호
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• pp.1-10
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• 2003

본 연구에서는 Metal-Ferroelecric-Semiconductor FET (MFSFET) 소자의 특성을 시뮬레이션 하였다. 시뮬레이션에서는 field-dependent polarization 모델과 square-law FET 모델이 도입되었다. MFSFET 시뮬레이전에서 C-V/sub G/ 곡선은 축적과 공핍 및 반전 영역을 확실하게 나타내었다. 게이트 전압에 따른 캐패시턴스, subthreshold 전류 그리고, 드레인 전류특성에서 강유전체 항전압이 0.5, 1V 일 때, 각각 1, 2V 의 memory window 를 나타내었다. 드레인 전류-드레인 전압 곡선은 증가영역과 포화영역으로 구성되었다. 드레인 전류-드레인 전압 곡선에서 두 부분의 문턱전압에 의해 나타난 포화드레인 전류차이는 게이트 전압이 0, 0.1, 0.2 그리고, 0.3V 일 때, 각각 1.5, 2.7, 4.0 그리고 5.7㎃ 이었다. 시간경과 후의 드레인 전류를 분석하였는데, PLZT(10/30/70) 박막은 10년 후에 약 18%의 포화 전류가 감소하여 우수한 신뢰성을 보였다. 본 모델은 MFSFET 소자의 동작을 예측하는데 중요한 역할을 할 것으로 판단된다.

• E2M - 전기 전자와 첨단 소재
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• 제9권7호
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• pp.690-695
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• 1996

We have systematically investigated the characterization of V$_{2}$O$_{5}$ thin films as a counter electrode for lithium based complementary electrochromic devices. The V$_{2}$O$_{5}$ thin films were prepared by thermal vacuum evaporation with varing the substrate temperature and film thickness. In electrochromic devices for smart windows, the WO$_{3}$ thin films with 400-800 nm thickness require to be capable of reversibly injection 10-15 mC/cm$^{2}$ of lithium, which is readily accomplished charge-balanced switching in a V$_{2}$O$_{5}$ thin films with 100-150nm thick. The V$_{2}$O$_{5}$ thin films produces considerably small changes in optical modulation properties in the visible and near infrared region(500-1100 nm) compared to the amorphous WO$_{3}$ thin films on 10-15 mC/cm$^{2}$ of lithium injection and the V$_{2}$O$_{5}$ thin films can therefore act as a counter electrode to WO$_{3}$ in a lithium based complementary clectrochromic devices. After 10$^{5}$ coloration/bleaching switching time, the degradation does not occurs and the devices exhibit a stable optical modulation in V$_{2}$O$_{5}$ thin films. It has shown that the injected lithium ion amounts in crystalline V$_{2}$O$_{5}$ thin films with the same thickness is large by 3-5 mC/cm$^{2}$ of lithium compared to the amorphous thin films in the same driving conditions. Therefore, to optimize the device performance, it is necessary to choose an appropriate film thickness and crystallinity of V$_{2}$O$_{5}$ for amorphous WO$_{3}$ film thickness as a working electrode.

• 자동차안전학회지
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• 제14권2호
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• pp.70-74
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• 2022

This paper describes the development of a target vehicle state estimation algorithm using vehicle-to-vehicle (V2V) communication. Perceiving the state of the target vehicle has great importance for successful autonomous driving and has been studied using various sensors and methods for many years. V2V communication has advantage of not being constrained by surrounding circumstances relative to other sensors. In this paper, we adopt the V2V signal for estimating the target vehicle state. Since applying only the V2V signal is improper by its low frequency and latency, the signal is used as additional measured data to improve the estimation accuracy. We estimate the target vehicle state using Extended Kalman filter (EKF); a point mass model was utilized in process update to predict the state of next step. The process update is followed by measurement update when ego vehicle receives V2V information. The proposed study evaluated state estimation by comparing input V2V information in an experiment where the ego vehicle follows the target vehicle behind it.

• 농업과학연구
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• 제47권1호
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• pp.173-182
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• 2020

Human Astrovirus (HuAstV), known as a waterborne virus, is a group IV positive-sense single-stranded RNA that belongs to Astroviridae. The first outbreak of HuAstV was reported in England in 1975. HuAstV can exist not only among clinical patients but also in various water environments, such as water for agriculture and vegetables. For diagnosis of HuAstV from water samples, a polymerase chain reaction (PCR) system has been developed. However, the PCR-based diagnostic method has problems in field application, such as reaction time, sensitivity and specificity. For this reason, in this study we developed the loop-mediated isothermal amplification assay (LAMP) system, aimed specifically at HuAstV. Three prepared LAMP primer sets were tested by specificity, non-specificity and sensitivity; one LAMP primer set was selected with optimum reaction temperature. The developed LAMP primer set reaction conditions were confirmed at 62℃, and detection sensitivity was 1 fg/μL. In addition, restriction enzyme HaeIII (GG/CC) was introduced to confirm that the LAMP reaction was positive. As a result, selected LAMP primer set was 100 - 1000 times more specific, rapid, and sensitive than conventional-nested PCR methods. For verification of the developed LAMP assay, twenty samples of cDNA from groundwater samples were tested. We expect that the developed LAMP assay will be used to diagnose HuAstV from various samples.