암석 슬러지를 이용한 건자재 개발

이필호,이구연,전철수,연규석,이윤수,인교진 강원대학교 부설 석재복합신소재 제품연구센터 2000 석재연 논문집 Vol.5 No.-

본 연구는 1993년부터 춘천시 신동면 형돌리 산 62번지 내에서 흑운모 화강암 및 편마암 암석을 원자재로 사용하여 건설기초재료인 쇄설골재 및 인공모래를 생산하는 업체로부터 제품 생산 후 발생하는 토양 스러치 케익이 연간 약 10만 입방정도 발생한다는 사실에 기초하여 석산에서 채취된 페잔토(석분)의 화학적, 물리적, 역학적 특성을 조사하여 석분의 이용 가능성을 확인하기 위한 실험으로 단위 시멘트량을 400kg, 잔골재율을 45% 그리고 물-시멘트비를 65%로 고정하고 잔골재 중 석분을ㄹ 0%, 10%, 20%, 30%, 40%, 50% 및 60%로 치환하여 제조된 콘크리트의 기초적 성질을ㄹ 시험하였다. 그 결과 석분의 치환율이 높을 수록 공기량은 증가하고 슬럼프값이 감소하였는데 이는 미세한 입자인 석분을 잔골재의 일부로 치환함으로써 비표면적이 증가하였기 때문인 것으로 사료된다. 압축강도와 휨강도는 모두 석분의 치환율이 증가할수록 압축강도와 휨강도는 다소 감소하는 경향을 나타냈으나 큰 성능차이는 보이지 않는 다는 것을 알 수 있었다. 이상의 실험을 통해 석분을 시멘트 콘크리트에 사용했을 경우 약간의 성능저하는 있지만 잔골재로의 활용이 가능하다는 것을 알 수 있었다. 그러므로 앞으로 건조수축, 균열, 크리이프 특성 및 내구성에 과한 연구가 더욱 심도있게 이루어져야 폐자원인 석분의 이용이 가능하리라 판단된다. This study aims to make cement concrete using crushed stone fines which are produced at Chuncheon city, Hyuldongri and find it's applications. According to the experimental results, when ratio of crushed stone fines was increased, air contents were increased and slump values were decreased. Also, the compressive strength and flexural strength were decreased when ration of crushed stone fines was increased. Although these strengths are decreased, the crushed stone fines can be used to construction materials because the decreased amounts are not so much.

Mo 화학기상증착에 있어서 불순물 농도에 미치는 증착조건의 영향

배상석,서성교,홍은식,김승모,조미정,한혜정,이두성,김세훈,민석홍 국립7개대학공동논문집간행위원회 2001 공업기술연구 Vol.1 No.-

The thermal decomposition process of Mo(CO)_6 on chemical vapor deposition was investigated by analyzing the effects of deposition temperature, pressure, and reaction gas on the phase change of deposited films. Mo_2C was deposited at or below 350℃ due to the incompleteness of thermal decomposition of Mo(CO)_6, but Mo films was successfully deposited at 400℃ or higher temperatures. The variation of deposition pressure did not change the dependence of decomposition process on deposition temperature. The activation energy of surface reaction was 5.8 ㎉/mole.

황색종 원료잎담배 숙성과정중 지습에 따른 품질변화

송교철,석영선,이학수 충북대학교 엽연초연구소 2001 煙草硏究 Vol.18 No.-

This study was carried out to investigate the influence of the dampness of concrete floor in storeroom on the quality of packed flue-cured leaf tobacco with corrugated causes for aging. The results were summarized as follows. The moisture and relative humidity conditions at the 15cm height from the concrete floor were 2.2℃ lower and 16% RH higher than those at the 300 cm height in the storeroom. Due to loading position, no significant changes in moisture content of leaf tobacco in the third layer was found. However, in the first layer, 2.4% of increase in moisture content was found. In the case of the layer, the circumference of corrugated casses was increased more largely than in the middle. During aging, the nicotine and total sugar content and pH value in leaf tobacco were decreased. Due to loading position, the pH, nicotine and total sugar content of leaf tobacco in the first layer were decreased significantly than those in the third layer. After aging, the degree of the lightness(L) and the yellowness(b) of leaf tobacco in the first layer were dropped by 3.2 and 2.5, respectively. However, the degree of the redness(a) was Increased by 0.63. Mold was occured in the leaf tobacco at the low part of the first layer.

트랙터의 자율주행 제어에 관한 연구

채창현,오영석,금교운,최한고,채석,김학성,이상재 金烏工科大學校 産業技術開發硏究院 1999 産業技術開發硏究 Vol.15 No.-

Recently, the research on the automatic mobile tractors has become active, especially steering control system. It is required that the steering system is able to robust to external loads, and to have large torque in a small area. The steering system consists of hydraulic components, mechanical parts, a steering actuator replacing the steering wheel, and a control device. In this paper, we proposed the steering fuzzy-control algorithm for automated tractor and its effectiveness has been shown by field test on the straight road, s-type road, and crank-type road.

MUC Expression in Gallbladder Epithelial Tissues in Cholesterol-Associated Gallbladder Disease

( Kyo-sang Yoo ),( Ho Soon Choi ),( Dae Won Jun ),( Hang Lak Lee ),( Oh Young Lee ),( Byung Chul Yoon ),( Kyeong Geun Lee ),( Seung Sam Paik ),( Yong Seok Kim ),( Jin Lee ) 대한간학회 2016 Gut and Liver Vol.10 No.5

Background/Aims: Gallstone pathogenesis is linked to mucin hypersecretion and bacterial infection. Several mucin genes have been identified in gallbladder epithelial cells (GBECs). We investigated MUC expression in cholesterolassociated gallbladder disease and evaluated the relationship between mucin and bacterial infection. Methods: The present study involved 20 patients with cholesterol stones with cholecystitis, five with cholesterol stones with cholesterolosis, six with cholesterol polyps, two with gallbladder cancer, and six controls. Canine GBECs treated with lipopolysaccharide were also studied. MUC3, MUC5AC, MUC5B, and MUC6 antibodies were used for dot/slot immunoblotting and immunohistochemical studies of the gallbladder epithelial tissues, canine GBECs, and bile. Reverse-transcription polymerase chain reaction was performed to evaluate MUC3 and MUC5B expression. Results: MUC3, MUC5AC, MUC5B, and MUC6 were expressed in the normal gallbladder epithelium, and of those, MUC3 and MUC5B exhibited the highest expression levels. Greatly increased levels of MUC3 and MUC5B expression were observed in the cholesterol stone group, and slightly increased levels were observed in the cholesterol polyp group; MUC3 and MUC5B mRNA was also upregulated in those groups. Canine GBECs treated with lipopolysaccharide also showed upregulation of MUC3 and MUC5B. Conclusions: The mucin genes with the highest expression levels in gallbladder tissue in cholesterol-associated diseases were MUC3 and MUC5B. Cholesterol stones and gallbladder infections were associated with increased MUC3 and MUC5B expression. (Gut Liver 2016;10:851-858)

Novel Discontinuous PWM Method for a Single-Phase Three-Level Neutral Point Clamped Inverter With Efficiency Improvement and Harmonic Reduction

Lee, June-Seok,Kwak, Raeho,Lee, Kyo-Beum Institute of Electrical and Electronics Engineers 2018 IEEE transactions on power electronics Vol.33 No.11

<P>This paper proposes a novel discontinuous pulse-width modulation (DPWM) method to reduce the current harmonics and improve the system efficiency for a single-phase three-level neutral-point clamped inverter. In single-phase inverters, the unipolar pulse-width modulation (UP-PWM) method is commonly used. However, this method has the disadvantage of power losses due to numerous switching operations. Conventional DPWM methods reduce the power losses and improve efficiency but increase the current total harmonic distortion (THD). To overcome these weaknesses, this paper proposes a hybrid DPWM switching method combining two PWM methods: the UP-PWM method and the conventional DPWM method called one-pole clamped PWM method. Since the proposed DPWM method offers all the advantages of both PWM methods, the optimal performance—with regard to the power losses and current THD—is obtained. The combination of two PWM methods is investigated by analyzing the power losses and current THD. Based on the analysis, the process determining the optimal operating condition is introduced. The effectiveness of the proposed DPWM method is demonstrated through simulations and experiments.</P>

Fault-Tolerant Strategy using Neutral-Shift Method for Cascaded Multilevel Inverters Based on Level-Shifted PWM

Seok-Min Kim,June-Seok Lee,Kyo-Beum Lee 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Most proposed methods for a fault-tolerant operation in many of studies are based on a phase-shifted PWM (PS-PWM) method. However these methods are not applied directly to multilevel inverter systems using a levelshifted PWM (LS-PWM). This paper focuses on faulttolerant operation for a cascaded multilevel inverter based on LS-PWM. During the occurrence of a single-inverter-cell fault, reconfiguration of the carrier bands scheme is implemented and modulation assignment of inverter cells is modified in this proposed fault-tolerant operation. It is possible to generate balanced three-phase line-to-line voltages and line currents with the proposed strategy when a device failure occurs in cascaded multilevel inverters using LS-PWM. The feasibility of the proposed method is proved by simulation results.

Novel switching method for single-phase NPC three-level inverter with neutral-point voltage control

Lee, June-Seok,Lee, Seung-Joo,Lee, Kyo-Beum Taylor & Francis 2018 International Journal of Electronics Vol. No.

Tolerance Control for the Inner Open-Switch Faults of a T-Type Three-Level Rectifier

Lee, June-Seok,Lee, Kyo-Beum The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6

The T-type topology is a three-level topology that has an advantage in terms of its number of switching device and its efficiency when compared to the neutral-point clamped (NPC)-type topology. With the recent increase in the usage of the T-type topology, the interest in its reliability has also increased. Therefore, a tolerance control for a T-type rectifier is necessary to improve the reliability of applications when an open-switch fault occurs. NPC-type rectifiers cannot eliminate input current distortion completely. However, the T-type rectifier is able to restore distorted current. In this paper, a tolerance control for the $S_{x2}$ and $S_{x3}$ open-switch faults of a T-type rectifier is proposed where it is advantageous in terms of efficiency when compared with other tolerance controls. The performance of the proposed tolerance control is verified through simulation and experimental results.

Wide-Range Sensorless Control for SPMSM Using an Improved Full-Order Flux Observer

Lee, Kyoung-Gu,Lee, June-Seok,Lee, Kyo-Beum The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3

A sensorless control method was recently investigated in the robot and automation industry. This method can solve problems related to the rise of manufacturing costs and system volume. In a vector control method, the rotor position estimated in the sensorless control method is generally used. This study is based on a conventional full-order flux observer. The proposed full-order flux observer estimates both currents and fluxes. Estimated d- and q-axis currents and fluxes are used to estimate the rotor position. In selecting the gains, the proposed full-order flux observer substitutes gain k for the speed information in the denominator of the gain for fast convergence. Therefore, accurate speed control in a low-speed region can be obtained because gains do not influence the estimation of the rotor position. The stability of the proposed full-order flux observer is confirmed through a root-locus method, and the validity of the proposed observer is experimentally verified using a surface permanent-magnet synchronous motor.