• Korean Journal of Ichthyology
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• v.9 no.1
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• pp.15-21
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• 1997

The influence of delayed(1, 2, 3, 4 days) feeding and starvation on morphological change and survival rate of the spotted sea bass larvae was examined at the KORDI laboratories which located at Poryong Power Plant, Poryong-gun, Chungchongnam-do in November, 1996. 1. The larvae of spotted sea bass began to feed on rotifers at 5 days after hatching. In case of non-feeding, all of the larvae died at 9 days after hatching. The larvae which fed 1 day after the normal first feeding schedule(1 day delayed) grew normally and 2 days delayed groups showed 5.3% in survival rate at 9 days after hatching. In case of non-feeding and 3 or 4 days delayed groups, all of the larvae died between 9 and 10 days after hatching. 2. In case of non-feeding, total length of the larvae decreased gradually. 3. The percente ratio of gut height and mytome height to standard length in starved larvae has declined most rapidly compare to other demensions during the non-feeding period. The percente ratio of gut height to mytome height had also difference between unfed and fed larvae. At 9 days after hatching, the ratio of that between fed and unfed larvae were 84.5 % and 52.4 %, respectively. 4. The morphology of starving larvae were characterized as sharpened jaw, projected edge of lower part of clavicle and bending trunk with slenger gut.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.196-201
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• 2001

This study reveals the thin sheet metal process with multi-forming die that the name is progressive die, as a pilotless type, also high precision production part is made. They require analysis of many kinds of important factors, i.e. theory and practice of metal press working and its phenomena die structure, machining condition for die making, die material, heat treatment of die components, know-how and so on. In this study, we designed and constructed a multi-forming progressive die as a bending and drawing working of multi-stage and performed through the try out for thin sheet metal. Out of the characteristics of this paper that nothing might be ever seen before such as this type of research method on the all of processes of thin and high precision production part.

• The Korean Journal of Ecology
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• v.19 no.6
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• pp.575-582
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• 1996

Molipteryx fuliginosa (Uhler, 1860) is a plant juice sucker which feeds on new tips of Rubus oldhami Miquel and Zelkowa serrata Makino, and it has a strong preference for teses two plants in Korea. M. fuliginosa has one generation a year and hibernates as a young adult. Most of the winter survivors emerge in early May. It is the first time their host plants were found and reported. Females mainly lay their eggs one by one separately on the leaves of R. oldhami, and even on the steel wire, the lid guaze and the ground in the laboratory. Nymphs do not gather, but stay on the hatching site, Nymphs except the non-feeding first instar feed on young shoots. From the second to the fifth instar nymphs migrate to the upper part of the shoot and congregate in part on an expanded leaf. The new adults first appeared on 11 August, and remained in the host plant, and fed on until mid October. The duration of the hatching and molting, and the survivorship curve based on the laboratory rearing were determined.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.2
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• pp.45-51
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• 2003

The multi-piloting type progressive die for U-bending sheet metal production part is a very specific division. This study reveals the sheet metal forming process with multi-forming die by center carrier type feeding system. Through the FEM simulation by DEFORM, it was accepted to u-bending process as the first performance to design of strip process layout. The next process of die development was studied according to sequence of die development, i.e die structure, machining condition for die making, die materials, heat treatment of partially die components, know-how and so on. The feature of this study is the die development of scrapless progressive die of multi-stage through the modeling on the I-DEAS program, components drawing on the Auto-LISP, CAD/CAM application, ordinary machine tool operating and revision by tryout.

• Korean Journal of Materials Research
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• v.9 no.2
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• pp.139-143
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• 1999

Solidification simulation of gray cast iron sheave product was conducted with the consideration of graphite precipitation during solidification, and of casting processes such as post-inoculation method, treatment and rate, the result of which was aimed to be adopted in the field. In risering design(I), shrinkage cavities were predicted to occur in the part below the risers and center part of the product. While the former defect was considered to be due to the solidification behaviour of riser neck, the latter was due to the feeding channel. In design(II), the length of the riser neck was reduced and one top open riser was attached in the center of the product to prevent the formation of shrinkage cavities, whereby defect-free product was produced.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.289-294
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• 2001

This study reveals the thin sheet metal Process with multi-forming die that the name is progressive die, also high precision production part is made. They require analysis of many kinds of important factors, i.e. theory and practice of metal press working and its phenomena, die structure, machining condition for die making, die material, heat treatment of die components, know-how and so on. In this study, we designed and constructed a multi-forming progressive die as a bending working of multi-stage and peformed through the try out. Out of the characteristics of this paper that nothing might be ever seen before such as this type of research method on the all of processes of thin and high precision production part.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.493-498
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• 2003

Harmonic current originating from electric locomotives can be magnified due to the impedance characteristics of power supply circuit and bring about various problems. That is, electromagnetic interference with communication lines, operational trouble in signaling, overheat and/or vibration in power capacitor, mis-operation in protection relay and so on. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. For these reasons, this study propose a new approach to model and to analyse traction power feeding system focused on system response to current and voltage harmonic(PART I ). Measurements of harmonics are also performed for railway power supply systems under normal operation. Spectrum and distortion analyses in measurement data are variously described in PART II

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.499-504
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• 2003

Harmonic current originating from electric locomotives can be magnified due to the impedance characteristics of power supply circuit and bring about various problems. That is, electromagnetic interference with communication lines, operational trouble in signaling, overheat and/or vibration in power capacitor, mis-operation in protection relay and so on. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. For these reasons, this study propose a new approach to model and to analyse traction power feeding system focused on system response to current and voltage harmonic(PART I ). Measurements of harmonics are also performed for railway power supply systems under normal operation. Spectrum and distortion analyses in measurement data are variously described in PART II

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.181-189
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• 2010

개방형 액체로켓엔진 시스템에 대한 동특성 예측 프로그램을 작성하였다. 이 프로그램을 통해 얻은 펌프 시동 시 시간에 따른 압력 및 유량 변화 결과를 수류실험장치를 구축하여 실험적으로 검증하였다. 수류실험장치는 실제 액체로켓엔진 추진제 공급 계통에서 구성품의 형태와 배치위치, 가스발생기와 주연소실로 분기되는 유량비를 기준으로 모사되었다. 측정 시 관로가 채워진 상태에서 펌프를 시동하였으며 펌프는 전동기로 구동된다. 동특성 예측 프로그램의 작성을 위해 구성품별 동특성 모델링을 수행하고 엔진 시스템을 기준으로 각 모델링을 순차적으로 통합하였다. 구성품의 동특성 파라미터를 측정 반영하였고 압력 밸런싱을 통해 수렴 조건이 결정된다. 수렴된 밀도와 유량을 가지고 다음 시간에서의 초기 입력 값으로 대체하여 계산을 수행하였다. 천이 작동 상태에서 엔진 시스템 내의 물리량 변화를 전산 예측과 더불어 실험적으로 측정하고 비교하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.54-60
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• 2010

액체로켓엔진 시스템의 시동 및 정지 또는 추력 제어와 같은 천이 작동시 동특성을 예측하기 위한 선행 연구로서 추진제 공급 시스템의 구성품에 대한 동특성 모델링을 수행하였다. 연료 공급계통과 산화제 공급 계통의 구성품들은 재생냉각채널을 제외하고 같은 것으로 가정하였다. 동특성 모델링의 대상 구성품은 펌프, 관로, 오리피스, 제어 벨브, 재생냉각채널, 인젝터 등이며 실제 엔진 시스템의 축소모형에 대한 수력시험을 통해 각 구성품의 동특성 모델링을 검증하였다.