• Bulletin of the Korean Chemical Society
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• 제18권9호
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• pp.916-922
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• 1997

A superconducting phase La2CuO4+δ (Tc=44 K) has been prepared by electrochemical oxidation which allows the oxygen to intercalat into the La2O2 layers. According to the Cu K-edge X-ray absorption near edge structure spectroscopic analysis, the oxidized phase shows an overall spectra shift of about 0.5 eV to a higher energy region compared to the as sintered one with the occurrence of an additional peak corresponding to the transition to the |1s13dn+1L-14pσ1 > final state, indicating the oxidation of CuO2 layer. From the X-ray photoelectron spectroscopic studies, it is found that the binding energy of La 3d5/2 is significantly shifted from 834.3 eV (as sintered La2CuO4) to 833.6 eV (as electrochemically oxidized La2CuO4+δ), implying that the covalency of the (La-O) bond is decreased due to the oxygen intercalation. The O 1s spectra do not provide an evidence of the superoxide or peroxide, but the oxide (O2-) with the contaminated carbonate (CO32-) based on the peaks at 529 eV and 532 eV, respectively, which is clearly confirmed by the Auger spectroscopic analysis. Oxygen contents determined by iodometric titration (δ=0.07) and thermogravimetry (δ=0.09) show good coincidence each other, also giving an evidence for the "O2-" nature of excess oxygen. From the above results, it is concluded that "O2-" appeared as O 1s peak at 528.6 eV is responsible for superconductivity of La2CuO4+δ.

• 한국식품위생안전성학회지
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• 제12권1호
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• pp.9-14
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• 1997

Vibrio mimicus is a closely related species with V. cholerae, and has been reported to be associated with gastrointestinal infections. Although extraintestinal infections of these vibrios have also been reported in Japan and Southeast Asia. But little research papers on V. mimicus was reported in Korea. Therefore, we tried to isolate V. mimicus from the environmental sea water from April to July in Pusan, Korea. Among the isolated strains, we selected the strongest hemolytic strain and then named V. mimicus SM-9. In this paper, we checked the antibiotic susceptibility and psychrotrophic characteristics of the isolated strain. Hemolytic activity of the hemolysin produced by the isolated strain was also measured. V. mimicus was not detected from the sea water samples in April and May, but its detection rate was relatively high in June and July in Pusan, Korea. The bacteriological characteristics of V. mimicus SM-9 were Gram-negative rods, motile, oxidase positive, Voges-Proskauer negative and sucrose negative. In 23 kinds of antibiotics susceptibility test, V. mimicus SM-9 showed susceptibility to the most of antibiotics submitted while it was resistive against lincomycin, oxacillin, rifampin and vancomycin. Hemolytic activity of the hemolysin produced by V. mimicus SM-9 was highest in stationary phase of the growth curve in BHI broth at 37$^{\circ}C$ and its activity was reached 18 HU per $m\ell$ of culture supernatant. For checking the psychrotrophic property of V. mimicus SM-9, the decreasing rate of the strain in phosphate buffer solution and yellowtail flesh homogenate was examined during the storage at 4, 0, -4 and -2$0^{\circ}C$. The decreasing rates of the selected strain stored in phosphate buffer solution were greater than those in fish homogenate. Decreasing rates of V. mimicus SM-9 stored in phosphate buffer solution were not significantly different by the storage temperatures. The viable cell counts of the strain were decreased as 5 log cycles after 120 hours at all the tested temperatures. While decreasing numbers of the strain in fish homogenates were 2*4 log cycles after 120 hours. The decreasing pattern of the strain numbers were very slow after 200 hours at all the stored temperatures.

• 센서학회지
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• 제6권2호
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• pp.137-144
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• 1997

본 논문에서 설계된 시스템은 ${\pm}2.5\;V$ 또는 +5 V의 환경에서 40 MS/s의 샘플링 속도로 약 70 mW의 정전력을 소비하는 고속 신호 처리용 CMOS 10 비트 파이프라인 A/D 변환기이다. 제안된 A/D 변환기는 각 단 사이의 신호를 빠르게 처리하고, 비교기 옵셋에 대한 넓은 보정 범위를 허용하기 위해 단당 1.5 비트 구조를 사용하였다. 고속 저전력 파이프라인 A/D 변환기의 설계를 인해 특별한 성능을 가진 연산 증폭기를 필요로 함에 따라 기존의 폴디드-캐스코드 구조를 기본으로한 이득 향상 구조의 연산 증폭기를 설계하였다. 특히, 연산 증폭기 자동 설계 도구인 SAPICE의 자체 개발로 최적의 성능을 가진 연산 증폭기를 구현하였다. 그리고 신호 비교 시에 소비되는 전력을 감소시키기 위해 정전력을 거의 소비하지 않는 비교기를 채용하였다. 제안된 A/D 변환기는 $1.0{\mu}m$ n-well CMOS 공정을 이용하였으며 ${\pm}0.6$ LSB의 DNL, +1/-0.75 LSB의 INL, 그리고 9.97 MHz의 입력 신호에 대해 56.3 dB의 SNDR의 특성을 보였다.

• International Journal of Advanced Culture Technology
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• 제10권1호
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• pp.230-235
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• 2022

This study is to select an optimal object detection algorithm for designing a self-checkout counter to improve the inconvenience of payment systems for products without existing barcodes. To this end, a performance comparison analysis of YOLO v2, Tiny YOLO v2, and the latest YOLO v5 among deep learning-based object detection algorithms was performed to derive results. In this paper, performance comparison was conducted by forming learning data as an example of 'donut' in a bakery store, and the performance result of YOLO v5 was the highest at 96.9% of mAP. Therefore, YOLO v5 was selected as the artificial intelligence object detection algorithm to be applied in this paper. As a result of performance analysis, when the optimal threshold was set for each donut, the precision and reproduction rate of all donuts exceeded 0.85, and the majority of donuts showed excellent recognition performance of 0.90 or more. We expect that the results of this paper will be helpful as the fundamental data for the development of an automatic payment system using AI self-service technology that is highly usable in the non-face-to-face era.

• 한국세라믹학회지
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• 제37권3호
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• pp.219-226
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• 2000

Amorphous Ge20As20Se60 chalcogenide thin films were prepared by spin coating technique from mixed solutions of As40Se60 and Ge40Se60 dissolved in ethylenediamine. Films were prepared at a roating speed of 3500 rpm and spinning time was 10 second and heat-treateed at 27$0^{\circ}C$ for 1 hour. The resulting film thickness and RMS roughness were approximately 340 nm and 15$\AA$. Photostructure changes were investigated with 514.5nm Ar+ laser irradiation and heat-treatment. After Ar+ laser irradiation, transmittance and transmission efficiency decreased respectively up to 24.9% at 2.43 eV and 67.5% at 3.27 eV, and absorption edge shifted toward long wavelength. Optical bandgap changed from 2.03 to 1.83 eV, and absoprtion coefficient and absorption efficiency increased up to 0.33$\times$105cm-1 at 3.37eV and 88.3% at 1.31 eV, respectively. These photodarkening state were recovered reversibly by heat-treatment at 27$0^{\circ}C$ for 1 hour. Photodarkening and thermal bleaching effects by laser irradiation and heat-treatment revealed reversible amorphous-to-amorphous transition varying only coordination number.

• 한국전기전자재료학회논문지
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• 제14권5호
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• pp.362-369
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• 2001

The electrical properties of varistors consisting of Zn-Pr-Co-Cr-Er oxides were investigated in the Er$_2$O$_3$content range of 0.0 to 2.0 mol%. the varistors without Er$_2$O$_3$ exhibited a relatively low nonlinearity, which was 14.24 in the nonlinear exponent and 21.47 $\mu$A in the leakage current. However, the varistors with Er$_2$O$_3$ sintered at 1335$^{\circ}C$ for 1h exhibited very high nonlinear exponent of 70, in particular, reaching a maximum value of 78.05 in 2.0 mol% Er$_2$O$_3$, and those sintered at 1335$^{\circ}C$ for 2h exhibited the nonlinear exponent close to 50, in particular, reaching a maximum value of52.76 in 0.5 mol% Er$_2$O$_3$. The others except for 0.5 mol% Er$_2$O$_3$-added varistors exhibited very high instability resulting in a thermal runaway within a short time, even a weak DC stress. Increasing soaking time decreased the nonlinearity, but increased the stability. The varistors containing 0.5mol% Er$_2$O$_3$ sintered for 2h exhibited excellent stability, in which the variation rate of the varistor voltage and nonlinear exponent was -1.70% and -7.15%, respectively, under more severe DC stress such as (0.80 V$_{1mA}$/9$0^{\circ}C$/12h)+(0.85 V$_{1mA}$/115$^{\circ}C$/12h)+(0.90 V$_{1mA}$/12$0^{\circ}C$/12h)+(0.95 V$_{1mA}$/1$25^{\circ}C$/12h)+(0.95 V$_{1mA}$/15$0^{\circ}C$/12h).TEX>/12h).

• 전자공학회논문지SC
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• 제45권2호
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• pp.37-44
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• 2008

본 논문에서는 고속 링 발진기를 이용한 WLAN용 5.8 GHz PLL을 제안하였다. 제안한 PLL에 사용된 링 발진기는 부 스큐 지연방식을 이용하여 차동 구조로 설계되었다. 따라서 Power-Supply-Injected Noise에 둔감하며, 1/f Noise를 감소시키기 위하여 Tail Current Source를 사용하지 않았다. 제안한 링 발진기는 $0{\sim}1.8V$의 컨트롤 전압에 걸쳐 $5.13{\sim}7.04GHz$의 발진주파수를 보였다. 본 논문에서 제안한 PLL 회로는 0.18 um 1.8 V TSMC CMOS 라이브러리를 기본으로 하여 설계하였고 시뮬레이션을 통하여 성능을 검증하였다. 동작 주파수는 5.8 GHz이며, Locking Time은 2.5 us, 5.8 GHz에서의 소비 전력은 59.9mW로 측정되었다.

• 대한수의학회지
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• 제31권2호
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• pp.131-135
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• 1991

The purpose of this study was designed to compare the storage stage of spermatozoa in the utero-vaginal (U-V) glands and the infundibular glands of high-fecundity hens. These laying hens were assigned to four groups by date intervals after last artificial inseminations. The U-V glands and the infundibular glands in the tissue preparation of the each hen uterus were observed microscopically, and also the appearance rates of spermatozoa-contained U-V glands were compared with those of the infundibular glands. 1. The appearance rates of spermatozoa-contained U-V glands were found to be 27.8, 28.8, 19.9 and 11.1% respectively at the hen groups of 1, 3, 7 and 10 days after artificial insemination. 2. The appearance rates of spermatozoa-contained infundibular glands were found to be 0.5, 1. 1, 0.6 and 0.4% of 1, 3, 7 and 10 days after AI and number of spermatozoa contained in a infundibular glands tended predominantly to be 1 to 2. So this study concluded as follows: The appearance rates of spermatozoa-contained glands were found to be higher in the U-V glands than in the infundibular glands and also spermatozoa number per gland were more numerous in U-V glands than in infundibular glands.

• 한국미생물·생명공학회지
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• 제17권1호
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• pp.1-7
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• 1989

Transformant TSD-14의 starch 발효능을 향상시키기 위해, 52$^{\circ}C$에서 60분간의 열처리로써 regeneration능을 제거한 TSD-14의 protoplast와 C, tropicalis RCT-40 (lys-)의 protoplast를 20 mM CaC1$_2$를 함유한 30% PEG를 fusogenlc agent로 하여 융합시키고 최소배지상에서 fusant를 선별한 결과 4.4$\times$$10^{-5}$ 빈도로 fusant를 얻었다. Fusant들의 탄소원 자화능을 조사한 결과 parental strains의 성질이 동시에 존재함을 알 수 있었으며 cell volume은 Parental Strains에 비해 약 1.5배정도 크게 나타났다. 또한 fusant는 유전적으로 매우 안정하였으며, parent인 TSD-14와는 달리 $\alpha$-1, 6-glucosidic linkage를 가수분해할 수 있었다. Fusant중 가장 우수 한 FSC-14-75 균주는 15%의 liquefied potato starch로부터 8.7%(v/v)의 ethanol을 생성하였고 또한 이때의 fermentation broth에 0.3%의 peptone을 첨가한 경우, ethanol 생성은 9.3%(v/v) 수준으로 증가하여 총당에 대해 86.0%의 발효율을 나타냈으며 산업적 이용가능성을 시사하였다.

• Korean Chemical Engineering Research
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• 제52권5호
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• pp.558-563
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• 2014

고분자 전해질 연료전지의 성능과 내구성에 미치는 막 전극 접합체(MEA) 제조방법의 영향에 대해 연구하기 위해 닥터 블레이드 방법, 스프레이 방법, 스크린 프린트 방법 그리고 스크린 프린트+스프레이 방법에 의해 MEA를 제조하였다. 제조된 MEA를 체결한 단위전지의 성능을 측정해 각 MEA의 초기 성능을 비교하였다. 10초간 0.6V 일정전압 유지 후 0.9 V에서 10초간 유지하는 전극 열화 가속 시험(AST)을 각 MEA 적용해 내구성을 시험하였다. 전극 열화 가속 시험 6,000 사이클 전 후 I-V 곡선, 임피던스, 순환 전압측정법(CV), 선형쓸음 전기량측정법(LSV), 투과전자현미경(TEM) 등을 측정하였다. 닥터 블레이드 방법에 의해 제조한 MEA의 초기 성능이 제일 높았고, 스크린 프린트+스프레이 방법에 의해 제조한 MEA가 제일 낮은 열화 속도를 보였다.