• Journal of the Korean Society for Railway
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• v.5 no.4
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• pp.260-266
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• 2002

A numerical simulation has been performed to estimate the transient pressure variation in the tunnel when G7 test train passes through the test tunnel in the Kyoeng-Bu high-speed railway. A modified patched grid scheme is developed to handle the relative motion between a train and a tunnel. Also, a hybrid dimensional approach is proposed to calculate the train-tunnel interaction problem efficiently. An axi-symmetric unsteady Euler solve using the Roe's FDS is used for analyzing a complicated pressure field in tunnel during the test train is passing through the tunnel. Usually, this complex phenomenon depends ell the train speed, train length, tunnel length, blockage ratio between train and tunnel cross-sectional area, relative position between train and tunnel, etc. Therefore, numerical simulation should be done carefully in consideration of these factors. Numerical results in this study would be good guidance to make test plans, test equipments selection and to decide their measuring locations. They will also supply important information to the pressurization equipment for high-speed train.

• Korean Journal of Logic
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• v.16 no.1
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• pp.45-59
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• 2013

In his book Worlds and Individuals: Possible and Otherwise, Takashi Yagisawa Yagisawa argues that his own theory is better than Lewis's theory by showing that his own theory can deal with important objections to modal realism more successfully than Lewis's. In particular, Yagisawa claims that by adopting modal tenses, he can respond to many important objections to modal realism in a uniform way. In this paper, I argue that Lewis can also successfully respond to Peacocke's objection in an exactly parallel way to Yagisawa's by distinguishing existence at the actual world from existence at other possible worlds and that Yagisawa's response to van Inwagen's objection does not succeed. I conclude that Yagisawa fails to show that his own theory is better than Lewis's.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.697-701
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• 1996

King Sejong's Striking water-clock which brought in use on the first of July in 1434 was mainly composed of timekeeping and time announcing parts signalling twelve double-hours, and five night-watches and night-watch-divisions automatically by means of ball-operating jackworks. The clock was arranged with dual timekeeping system, the one for a full day(twelve double-hours) and the other for five night-watches achieving twelve double-hours and one-hundred interval horary systems. The vessels were arrayed in inflow-type water-clock, a large reservoir on the highest story, a constant-level tank for supplying water to the measuring vessel evenly in the middle, and the lowest tank to receive water from the above constant-level tank. An indicator-rod on the float was raised upwards depending on the water-level increase to show timing scales and also to release small bronze balls from the ball-rack mechanisms implanted on the measuring vessel to signal timing intervals.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.1
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• pp.9-13
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• 1986

An experiment on strawberry (Fragaria Grandflora EHRH) was conducted in order to compare the effect of two compound fertilizers made for this crop, by Kyonggi Chemical Crop. LTD. with that of muriate of potash, sulfate of potash and ammonium nitrate in a farmer's vinylhouse during the winter period of 1984 to 1985. Results obtained are as follows; 1. The effect of compound fertilizers on the growth, number of inflorescences and yield of strawberry showed no significant difference from the effect of muriate of potash, sulfate of potash and ammonium nitrate. But the former increased the content of reduced, and total sugars soluble in diluted acid in the juice of strawberry. 2. As a whole, sulfate of potash increased sugar content in strawberry juice more than muriate of potash, which became the reason to increase the sugar content in the strawberry juice harvested from the compound fertilizer plots.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.1
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• pp.40-47
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• 1998

The optical heads as the key parts of digital audio/video players are applied extensively from general household electric appliances to computer memory or game apparatuses, and the demand of them tends to be increased according to the extension of optical medium market. In this paper, the 2-axis actuator, the key component for focus servo and tracking servo of the optical head is designed as a type of the cantilever suspended by 4 wires. The design propriety is verified through its simulation and the characteristic analysis of its mock-ups. The other factors which influence the performance of 2-axis actuators besides the design factors of them, are also verified through the mock-up analysis.

• Monthly Duck's Village
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• s.98
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• pp.94-97
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• 2011

2010년 8월 오리고기 원산지 표시제가 제도화되어 시행중이다. 그러나 지난 연말 발생한 AI로 인해 오리고기 수급상황이 악화되면서 오리가격이 상승하였다. 그에 따라 중국산 훈제오리고기와 대만산 냉동오리의 수입량이 증가, 값싼 수입 오리고기를 재포장하여 국내산으로 둔갑 판매하거나 원산지 미표시 등 부정유통 사례가 크게 늘어나고 있다. 이에 협회는 국내 오리산업을 스스로 지키자는 취지에서 지난 5월 25일, 오리고기 유통 감시단을 발족하고 오리고기 원산지표시제의 조기정착을 위해 부정 유통 신고센터 운영을 본격 가동하고 있다. 지난 5월 전임 유통감시원으로 위촉된 김순이 양은선씨는 소비자 시민모임 회원으로 오리고기의 주요 소비처인 서울, 경기를 집중적으로 홍보 감시하면서 오리고기 원산지 표시제의 유통거래질서 확립에 기여하고 있다. 오리고기 유통감시원은 오리고기 원산지 표시 점검 및 부정유통을 감시함으로써 불법유통을 차단하고 오리고기 원산지표시제 정착을 위해 노력함은 물론 판매점 출입 시 명예감시원증을 제시, 방문목적을 밝히고 감시원으로서 품위를 유지하는 임무를 갖고 활동하고 있다. 오리고기 부정유통 사례를 막는 이들의 활동은 소비자와 오리 사육 농가를 보호하고, 올바른 정보전달을 통해 소비자의 신뢰를 구축할 수 있으며 이는 향후 오리고기 소비 확대에 기여할 수 있는 촉매의 역할이다. 평소 자발적으로 소비자 시민모임 활동에 참여하고 있는 김순이 양은선씨를 본지에서 만나봤다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.10-13
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• 2010

Low pressure combustion tests for TDM(Technology Demonstration Model) of 75 tonf thrust chamber were performed. It has design chamber pressure of 60 bar, propellant mass flow rate of 243.6 kg/s. Due to the limitation of the current firing test facility in Korea, the combustion tests were conducted to verify the operation and the combustion performance at low pressure condition (30 bar, 121.8 kg/s). All the tests had been successfully executed without the damage of the hardware. These test results can be used as fundamental data to predict the combustion performance at design point condition for 75 tonf thrust chamber.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.71-74
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• 2010

Using the technology demonstration model of 75-tonf-class combustor which is expected to be used to the rocket engine of a korean space launch vehicle, 2 times of firing tests were carried out. Firing tests were done at 50% of the nominal flow rate because of incapability of the test facility and limit of the test bed strength. Through the low pressure firing tests of 75-tonf-class channel cooling thrust chamber, reliability and stability at the ignition and combustion phases were confirmed. Additionally it was foreseen that the 75-tonf-class thrust chamber would satisfy the performance requirements.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.3
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• pp.7-13
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• 2019

Recently, an automobile market used to natural gas has emerged as fast-growing as the several countries, who holds abundant natural fuel resources, has promoted to supply the national agency for an automobile car. LNG fuel vessel is more efficient in another way as the energy density is high, but it requires a high technology and investment to maintain extreme low temperature. CNG fuel vessel are relatively low-cost alternative to LNG, but poorly economical in terms of energy density as well as showing safety issues associated with compressed pressure. The development of adsorbed natural gas (ANG) has emerged as one of potential solutions. Therefore, it is desirable to reduce the weight of vessel by applying light-weighed a composite carbon fiber in order to response to the regulation of $CO_2$ emission. Herein, this study make the prototype ANG vessel not only based on the optimal design and analysis of material characteristic but also based on the shape design, and it suggest a new type for the composite carbon fiber vessel which verified functional test. Moreover, the detail shape design is analyzed by a finite element analysis, and its verifies the ANG vessel.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.5
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• pp.53-64
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• 2021

SpaceX has lowered rocket launch cost innovatively and put first stage reuse to the practical use with Falcon 9. Now the company is developing Starship system that is fully reusable with the heaviest payload in the world. So the system can lower the cost much more and fulfull more diverse mission. For the system the company have developed Raptor engine which is a full-flow staged combustion cycle one with methane fuel. And for the full reusability the company is manufacturing and testing the system prototypes with the barely used technologies such as stainless steel tank, belly flop and retropropulsion during descent. In this study the specification, missions and design features of the system are investigated. Also the development processes of Raptor engine and initial 13 Starship prototypes, which have been manufactured very rapidly, are presented.