• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.987-988
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• 2006

The processes of P/M affect the properties of sintered gears. The different techniques of P/M lead to the different properties of sintered gears. This paper summarizes new progress in powder metallurgy for sintered gears. These progresses include warm compaction, high velocity compaction, sinter hardening, high temperature sintering, infiltration, CNC powder press and surface densification etc.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.389-390
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• 2006

Selective surface densification is a tool for improving the mechanical properties of PM steels, such that the requirements for highly loaded gears can be matched. This paper describes the manufacturing and the properties of a helical P/M gear. The gear performance was evaluated on a 3-shaft back to back test rig, on a load bearing test rig and on a sound test bench. The results of these tests are presented and compared to data obtained from solid steel gear with identical geometry and surface quality. This comparison indicates that P/M gears have a load bearing capacity and noise level which are both well comparable to solid steel gears.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.738-739
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• 2006

This paper will describe a powder and processing method that facilitates single press-single sintered densities approaching $7.5g/cm^3$. At this sintered density, mechanical properties of the powder metal (P/M) component are significantly improved over current P/M technologies and begin to approach the performance of wrought steels. High performance gears have the added requirement of rolling contact fatigue durability that is dependent upon localized density and thermal processing. Combining high density processing of engineered P/M materials with selective surface densification enables powder metal components to achieve rolling contact fatigue durability and mechanical property performance that satisfy the performance requirements of many high strength automotive transmission gears. Data will be presented that document P/M part performance in comparison to conventional wrought steel grades.

• 수산해양기술연구
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• 제55권1호
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• pp.1-6
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• 2019

The annual production of silver croaker (Argyrosomus argentatus) in Korean towed fishing gears has been increased in recent five years. In 2017, the annual production of silver croaker in metric ton was increased 99.2% compared to 2013. However, the research for silver croaker has been focused on ecology in Korea. There has not been enough research in terms of fishing gears. Therefore, the research for retention probability for towed gears was conducted on covered codend method from June, 2016 to July, 2018. During the experiments, the total catch of silver croaker was 1,563. The geometry of the experimental trawl gear was controlled by trawl monitoring system; net height was 3.3 m, distance of trawldoors was 59.8 m and distance of wing net was 17.3 m. The selection curve for silver croaker was estimated by a logit model. The analysis was applied with the confidence interval to reduce uncertainty of the estimation. The $l_{50}$ was 13.87 cm and its selection range was 2.71 cm. P-value was estimated at 0.99. The mesh size for silver croaker in towed gears needs to be adjusted by considering its minimum maturity length, stakeholder's interests and fisheries regulations.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1652-1655
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• 2005

All teeth on the cycloidal plate gear exist in the contact motion with rollers and the forces are interacted between roller gears with cycloidal plate gears. So, the contact forces and friction forces must be required to improve the accuracy in design procedures of cycloidal speed reducers. This paper presents a force analysis considered the friction effect approach derived by static force equilibrium condition, geometrical adaptation, instant velocity center method and relative velocity method. Finally, the paper develops CAD-program for the construction of the design automation using the proposed method.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.381-382
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• 2006

A comparative study is made on root bending fatigue performance of spur gears and plane bending fatigue performance of notched test bars. R = 0 root bending fatigue tests are made on small spur gears with critical root radius 1.0 mm. The results are compared to plane bending fatigue tests of 0.9 mm radius notched specimens. Results are presented for tests on 4%Ni/2%Cu/1.5%Mo prealloyed PM steel with addition of about 0.6% graphite. Predicted values from the test bars coincide well with the results obtained from the gear root fatigue tests.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.756-757
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• 2006

P/M enables the economical production of components for many kinds of gears. Functionally, the sub gear requires high tooth accuracy and bending fatigue strength. The whole tooth profile was sized after sintering to satisfy the gear tooth accuracy specification. The part was redesigned to reduce machining requirements. The required bending fatigue strength was achieved through appropriate material choice and induction of compressive residual stress by shotpeening after carburizing. The P/M sub gear replaced a forged steel gear, satisfied performance requirements, expanded the use of P/M applications and provided over 30% cost reduction.

• 생태와환경
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• 제53권2호
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• pp.156-164
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• 2020

The accurate estimation of fish assemblages is highly dependent on the sampling gear used for sampling. We used data from 15 sampling sites along the Nakdong River, which is a large river in South Korea, to identify differences in assemblages and sizes of freshwater fishes collected with either cast nets or gill nets, the two most commonly used sampling gear in South Korea. The two gears differed in the fish assemblages they captured, with more species caught by gill nets. Further, due to its tighter mesh size, the cast net caught significantly smaller fishes than the gill nets(independent t-test, p<0.05). We found the cast net to be appropriate for species that inhabit shallow (less than 2 m) and open water, but inappropriate for deep water, habitats with plant beds, and nocturnal species. Thus, cast net sampling is not efficient in a large river environment, and a combination of sampling methods is more suitable for understanding fish assemblages in such habitats. In general, appropriate selection of fishing methods to specific habitats is necessary to improve data quality and minimize the misrepresentation of environmental conditions.

• 한국수산과학회지
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• 제18권1호
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• pp.8-14
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• 1985

어구의 모형실험을 위한 회유수조를 제작하여 시험한 결과를 요약하면 다음과 같다. 1. 동력 50 H.P.의 D.C. Motor에 의하여 생기는 최대 유속은 약 2.3m/sec로서 지시전압 200 V, 지시전류 185 A에서 나타났다. 2. 유속과 전압과의 관계는 $0{\sim}1.0m/sec$까지는 비선형적으로 비례하나 1.0m/sec 이상에서 직선적으로 비례하였다. 3. 공칭 유속의 범위는 0.4m/sec에서 1.8m/sec까지이다. 그 이상으로 부터 최대 2.3m/sec까지는 수십분 이상 사용하며 모터의 과열현상이 나타났다 4. 수유 횡단면을 따르는 수직 유속분포는 수로중앙을 중심으로 좌우 약 70 cm까지는 0.2m/sec 이내의 차이를 나타냈다. 그러나 그 외부는 프로펠러의 크기, 벽과의 마찰로 인하여 급격히 감소한다. 5. 수심 중앙면을 따르는 수평적 유속 분포를 보면 유입부로 부터 관측부의 중앙까지는 수류변화가 거의 없으나 그 이후는 수로의 만곡에 따라 편향되었다.

• 한국환경생태학회지
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• 제38권3호
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• pp.263-276
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• 2024

신갈호의 어류군집 특징 및 어구별 채집 효과를 밝히기 위해 2020년 8월부터 2021년 10월까지 조사를 실시하였다. 채집 어구는 호소에서 일반적으로 사용되고 있는 족대와 투망, 자망, 정치망을 사용하였다. 조사결과, 조사기간 동안 채집된 어류는 7과 18종 3,501개체, 생체량 117,670g이었다. 개체수비 우점종은 참붕어(Pseudorasbora parva, 29.9%), 아우점종은 피라미(Zacco platypus, 25.1%), 다음으로 배스(Micropterus salmoides, 19.3%), 붕어(Carassius auratus, 9.1%), 밀어(Rhinogobius brunneus, 6.1%), 블루길(Lepomis macrochirus, 4.2%) 등의 순으로 우세하였으며, 생체량비 우점종은 붕어(45.1%), 아우점종은 잉어(Cyprinus carpio, 17.4%), 그 다음으로 배스(14.3%), 피라미(7.7%), 떡붕어(C. cuvieri, 7.4%), 참붕어(3.9%) 등의 순으로 우세하였다. 출현종 중 한국고유종은 몰개(Squalidus japonicus coreanus), 점줄종개(Cobitis nalbanti), 얼록동사리(Odontobutis interrupta) 3종이었으며, 외래어종은 배스, 블루길, 떡붕어, 향어(Cyprinus carpio nudus type) 4종으로 이중 배스와 블루길은 생태계교란 생물로 지정된 종이다. 주요종의 평균 체장과 체중을 조사한 결과, 우점종인 참붕어는 체장 60±24.1mm, 체중 4.4±3.42g이었고, 아우점종인 피라미는 체장 82±17.6mm, 체중 10.4±7.27g, 우세종 배스는 체장 96±25.1mm, 체중 24.9±96.02g, 붕어는 체장 125±77.3mm, 체중 168±336.5g이었다. 어구별 조사결과, 족대로 채집된 어류는 3과 8종 302개체 생체량 1,269g, 투망으로 채집된 어류는 4과 11종 948개체 생체량 31,343g, 자망으로 채집된 어류는 4과 13종 682개체 생체량 69,695g, 정치망으로 채집된 어류는 7과 15종 1,569개체, 생체량 15,362g으로 나타났다. 어구별 조사결과를 요약하면, 정치망은 종수와 개체수가, 삼중자망은 생체량이 가장 많았으며, 투망은 연안지대의 종수와 개체수를 채집하는데 강점이 있었으며, 족대는 종수와 개체수, 생체량 모두 가장 적었으나 연안지대의 저서성 소형어류를 채집하는데 강점을 보였다.