• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.6
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• pp.548-558
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• 1990

Physiology and genetics of early maturity in cereals are the subject of practical as well as scientific interest for agronomist and plant breeders, Thorough understanding of the true nature of such a complex character requires physiological and genetical knowledge about the internal factors, which are closely bound up with and react to some particular external or environmental factors. From the practical point of view. experiments should be conducted under controlled conditions. especially the day length and temperature, so that the genotypic differences pertaining to these factors may be discerned. Takahashi and Yasuda (1958, 1970) maintained that at least three physiological factors were responsible for determining earliness in barley. namely. (1) spring and winter habit of growth or vernalization requirement, (2) ogitioeruiduc response or sensitivity to short-day, and (3) earliness factor in a narrow sense or minimal vegetative growth. The same situations were true in common wheat also (Yasuda and Shimoyama, 1965), In this report. physiology and genetics of internal factors and their relations to the time of heading in the field will be presented with some problems concerning differences in mechanism of early maturity between barley and wheat.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.6
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• pp.106-113
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• 2009

A 6-DOF precision stage was developed based on parallel kinematics structure with flexure hinges to eliminate backlash, stick-slip and friction and to minimize parasitic motion coupled with motions in the other-axis directions. For the stage, lever linkage mechanism was devised to reduce the height of system for the enhancement of horizontal stiffness. Frequency response comparison between experimental results and mathematical model extracted from dynamics of the stage was performed to identify the system parameters such as spring constants and damping coefficients of actuation modules, which cannot be calculated accurately by analytic methods owing to their complicated structures. This newly developed precision stage and its identified model will be very useful for precision positioning and control because of its high accuracy and non-coupled movement.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.561-566
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• 2000

A screw driver is essentially used in assembling machine parts and electronic products such as the printed circuit board with a housing. As the parts to be assembled becomes small and precise, the higher precision of the controling screw driver torque is required. However, because the operator controls the fastening torque by his experience, it must be inexact. Thus the screw driver which can exactly control the fastening torque by a bellows is designed and developed in the study. The bellows is expanded by the inner air pressure and contracted and by the spring operation. The bellows driver is composed of the entrance solenoid valve, the exit solenoid valve and the pressure sensor. The pressure sensor senses the bellows pressure. When the pressure sensor output reaches the setting value, it operates the exit solenoid valve not to deliver further torque by letting the air of the bellows out. Through a series of experiments, the performance is studied and verified.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.114-114
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• 2000

In this paper a self-tuning modified skyhook control for the semi-active suspension systems is investigated. The damping force generation mechanism is modeled We consider a 2 DOF time-varying quarter car model that permits parameter variations of the sprung mass and suspension spring coefficient. The modified skyhook control algorithm proposed in this paper requires only the measurement of body acceleration. The absolute velocity of the sprung mass and the relative velocity of the suspension deflection are estimated by using integral filters, according to parameter variations. The skyhook gains are designed in such a way that the body acceleration and the dynamic tire force are optimized. An ECU prototype will be discussed

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.1067-1072
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• 1996

Sensitivity analysis of the cylindrical zigzag cams under acceleration and centrifugal forces is performed. A Lagrangian method is used to determine the mechanism constant of zigzag track, And the equation of motion for cylindrical zigzag cam under rectangular pulse is derived by the governing equations of a single spring mass system. The ratio of the drive force tn resisting force is derived by angular acceleration, centrifugal force and setback force on the operation of the munition. The theoretical sensitivity curves for 3 models are analyzed. And experiments for 3 models are conducted to check safe and functional zone. Zigzag cam types can be satisfied all major design requirements for switch system of munition.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.4
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• pp.131-138
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• 2001

In this paper, performance of a dry CVT vehicle with torque cam is investigated. Based on belt transmission mechanism and torque cam actuator characteristics, an algorithm which is able to calculate the speed ratio from given thrust and load torque is suggested and a 3-D map is constructed for the speed ratio-thrust-torque. Using the 3-D map, a steady state characteristic of torque cam and a transient response of a dry CVT vehicle are investigated by simulation. It is found that initial spring compression plays a key role in determining the sliding criteria and the speed ratio velocity.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1575-1580
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• 2009

Maglev vehicle has two kinds of suspension system such as a secondary suspension with air-spring and a primary suspension as electromagnetic suspension which composed of electromagnet, magnet driver, controller and sensors. The interaction between each dynamic component of vehicle and track effects the stability and running performance. To achieve the specified performance of vehicle, many various approaches of research were tried, then as the result of these efforts, the first commercial operating with Maglev will start soon. The bogie for revenue service from 2012 has some significant modifications compared to the previous one, and to verify the changes the half prototype vehicle was manufactured and took the running performance test. In this report, we will introduce the stage of manufacturing and report results of dynamic performance tests to verify new concept of bogie mechanism.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.385-392
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• 1998

Train crashes involve complex interaction between deformable bodies in multiple collisions. The purpose of this study is to suggest the effective analytical procedure using simple model for the crashworthiness of motorized trailer of high speed train. The simple model, with very short modeling time and reduced computation time was adopted to extract the global behaviour and to perform a pre-optimization of the considered structure. Firstly, various types of crash events are investigated and the conditions for numerical simulation are defined. The simple model, using the beam and non-linear spring element, and shell element model are used to evaluated energy absorption and deformation mechanism in analyses. And aluminum is applied to real model after verification with square tube analyses. Finally, loading path and energy absorption of main components are evaluated. The analyses are aimed to ensure the crashworthiness design of high speed train.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.5
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• pp.53-59
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• 2001

A screw driver is widely used in assembling machine parts or electronic products such as the printed circuit board with a housing. As the parts to be assembled becomes small and precise, the higher precision of the controlling screw driver torque is required. However, because the operator controls the fastening torque based on experience, it must be inexact and the setting procedure will be time consuming job. Thus the screw driver which can exactly control the fastening torque is developed utilizing a bellows in this paper. The bellows is expanded by the inner air pressure and contracted by the spring operation. The bellows type driver is composed of a clutch mechanism with two solenoid valves and a pressure sensor. Those valves are controlled using the detected bellows pressure by the sensor. When the pressure reaches the setting value, the exit solenoid valve is opened to release the air pressure from the bellows so as not to deliver further torque. Through a series of experiments, the performance is examined and verified.

• Proceedings of the KAIS Fall Conference
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• 2000.10a
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• pp.83-85
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• 2000

배선용 차단기의 개폐기구는 수동 조작력을 가동 접촉자에 전달하여 차단, 개폐의 동작을 행하는 것으로 Spring과 Link를 주체로 구성되어 있으며 기구부가 단락 차단 성능의 가장 큰 영향을 미친다. 제품 성능 개선을 위해 기구부를 변경하기 위해서는 많은 시행착오를 거치게 되는데 이 때 소요되는 시간과 비용을 줄이기 위해 동특성 해석이 널리 사용되고 있다. 본 논문에서는 제품의 동적 모델링을 위해 범용 동역학 해석 프로그램인 ADAMS(Automatic Dynamic Analysis of Mechanical System)을 이용하였고 설계 변경시 반복작업으로 인한 실패비용을 최소화하고 링크 지점의 최적값을 구하기 위해 민감도 해석과 최적화 기법을 도입하였다.