• Journal of Biosystems Engineering
• /
• 제17권4호
• /
• pp.396-403
• /
• 1992

In order to operate a combine harvester at the optimum conditions and maximum performance, a forward speed control system(FSCS) was designed and develped. The FSCS consisted of engine, continuously variable V-belt transmission, threshing unit, traveling unit, detecting unit, and controller. Each components of the system were mathematically modeled. By a computer simulation, the effects of control parameters such as hydraulic piston speed, speed ratio, dead band of engine speed on the system performance were analysed, and the optimum control conditions were identified. The system appeared to be the most stable at the hydraulic piston speed of 10.6mm/s and the speed ratio of 0.4. The proper dead band of engine speed appeared to be 30rpm through the simulation and verification tests.

• 한국지구과학회지
• /
• 제31권3호
• /
• pp.205-213
• /
• 2010

옥천대 우라늄 광화대 부근 퇴적암 지하수에 대한 수리지화학적 연구를 수행하여 옥천대 우라늄 광화대와 대전지역 우라늄 지하수와의 성인적 관련성을 고찰하였다. 지하수의 pH는 6.4-8.1의 범위로 중성에서 약칼리성 특성을 보이며, Eh는 대체로 -50-225 mV의 범위로서 일부는 환원성 환경의 특성을 보인다. 지하수는 탄산염광물의 용해반응으로 $Ca^{2+}$ 및 $HCO_3^-$ 함량이 우세한 Ca-$HCO_3^$ 유형에 해당된다. 석탄광산 폐수에서는 $1165{\mu}g/L$의 우라늄이 검출되었으나 지하수내 우라늄 함량은 $3.2{\mu}g/L$ 이하로 매우 낮다. 우라늄 광화대 부근 지하수에서 낮은 우라늄 함량은 낮은 Eh를 보이는 수리지화학적 특성에 기인한다. 대전지역 지하수 내 우라늄은 옥천대 우라늄 광화대로부터 공급되지는 않은 것으로 판단된다.

• 암석학회지
• /
• 제13권3호
• /
• pp.119-125
• /
• 2004

옥천변성대의 소위 문주리층에 분포하는 규장질 변성응회암의 U-Pb 저어콘 연대를 고분해능 이차이온질량분석기(SHRIMP)를 사용해 측정하였다. 10개의 저어콘 입자로부터 얻어진 13개의 점분석 자료는 대부분 일치연련성(concordia) 상에 찍히며, 이들로부터 구한 $^{206}$ Pb/$^{238}$ U 가중평균연대는 747$\pm$7Ma이다. 이 연대는 Lee et. al.(1998)이 전통적 방법으로 구한 U-Pb 저어콘 연대(756$\pm$Ma)보다 약간 적지만 두 연대측정 결과 모두 약 7.5억년 전 쌍모식 화산활동과 함께 대륙내 분지가 옥천대에서 발달하였음을 지지한다.

• Journal of Astronomy and Space Sciences
• /
• 제18권2호
• /
• pp.109-118
• /
• 2001

1992년에 발사된 우리별 1호는 고에너지 양성자들이 OBC(On-Board Computer)186의 메모리에 SEU(Single Event Upset)을 일으키는 안쪽 반알렌대(Inner Van Allen Radiation Belt) 를 통과한다. 본 논문에서는 Chi-Square 방법을 이용하여 OBC(On-Board Compute.)186 메모리에서 측정된 SEU 데이터와 NASA/NSSDC의 AP-8 양성자 모델을 비교하여, SEU를 유발하게 되는 문턱 에너지를 추정해 보았다. OBC186위치에서의 양성자 선속을 유도하기 위해서 위성체에 의한 차폐 효과가 고려되었으며 모델의 신뢰성을 높이기 위해 태양 활동이 활발한 기간에 얻어진 데이터들은 제거되었다. 비교 결과 우리별 1호 OBC186 주 메모리의 문턱에너지는 $110{pm}10MeV$로 추정 되었다.

• Journal of Astronomy and Space Sciences
• /
• 제36권2호
• /
• pp.45-60
• /
• 2019

The Earth's outer radiation belt has long received considerable attention mainly because the MeV electron flux in the belt varies often dramatically and at various time scales. It is now widely accepted that the wave-particle interaction is one of the major mechanisms responsible for such flux variations. The wave-particle interaction can accelerate electrons to MeV energies, explaining the observed flux increase events, and can also scatter the electrons' motion into the loss cone, resulting in atmospheric precipitation and thus contributing to flux dropouts. In this paper, we provide a review of the current state of research on relativistic electron scattering and precipitation due to the interaction with electromagnetic ion cyclotron (EMIC) waves in the inner magnetosphere. The review is intended to cover progress made over the last ~15 years in the theory and simulations of various issues, including quasilinear resonance diffusion, nonlinear interactions, nonresonant interactions, effects of finite normal angle on pitch angle scattering, effects due to rising tone emission, and ways to scatter near-equatorial pitch angle electrons. The review concludes with suggestions of a few promising topics for future research.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 춘계학술대회 논문집
• /
• pp.829-830
• /
• 2008

• 한국공작기계학회논문집
• /
• 제12권2호
• /
• pp.59-64
• /
• 2003

Continuously Variable Transmission (CVT) consists of a driving pulley and a driven pulley joined by rubber V-belt. Each pulley consists of a fixed flange and a movable flange. The main advantages of the U with V-belt, which has been Popular in Asia, are a simple mechanism less maintenance and low cost. One of the important factors which have an influence on the performance of the CVT is change of axial distance. Base on an experiment the effects of transfer torque and speed ratio of both driving pulley and driven pulley during the alteration of axial distance were studied.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 추계학술대회 논문집
• /
• pp.739-742
• /
• 1997

Continuously variable transmission(CVT) mechanisms are proposed, which can offer a backward mode, a geared neutral, an underdrive mode and an overdriver mode. They are not required of a starting device as a torque converter. CVT mechanisms developed here present two distinct operating modes which are a power circulation mode and a power split mode. The transition of two modes takes place at the particular CVU speed ratio. For these CVT mechanisms, performance analysis related to speed ratio, power ratio and theoretical efficiency are executed.

• 한국정밀공학회지
• /
• 제18권3호
• /
• pp.205-215
• /
• 2001

Continuously variable transmission(CVT) mechanisms considered here combine the functions of a 2K-H I type differential gear unit and a V-belt continuously variable unit(CVU). One shaft of the V-belt CVU is connected directly to the differential gear unit and remaining shaft of it is linked to the output shaft. These mechanisms have many advantage which are the decrease of CVT size, the increase of overall efficiency, the extension of speed ratio range, and the generation of geared neutral. In this paper six different mechanisms of output coupled type CVT are proposed. Some useful theoretical formula related to speed ratio, power flow and efficiency are derived and analyzed, and theoretical analysis are proven by various experiments.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제3권4호
• /
• pp.409-414
• /
• 2014

The parameters and operating characteristics of the switched reluctance motor (SRM) for the electric drive of the overland belt conveyor CLM-4500 have been presented. The motor power capacity has been equal to 1250 kW, the motor speed - 1000 min-1. SRM power supply has been provided by a three-phase voltage inverter and a 12-pulse rectifier circuit. The group electric drive has been installed on sections number 2 and 3, 3770 m and 3375 m length, respectively, on the areas of "Berezovsky Strip" JSC, a member of the Siberian Coal Energy Company.