• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.4
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• pp.67-72
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• 2016

Planetary gear sets are widely used in power transmission components, which have high efficiency and good durability. Their most important design parameter is the load-sharing characteristics among several planetary gears. In this study, the load sharing of planetary gears was analyzed according to the carrier pinhole position error of planetary gear sets. The loads acting on planetary gears varied with the pinhole position error of the carrier, and the load sharing of planetary gears improved as the input load increased. In addition, the load of the planetary gear with a carrier pinhole position error was relatively higher than that of other planetary gears without carrier pinhole position errors. This trend appeared more clearly in the non-floating-type carrier than the floating-type carrier.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.12
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• pp.7-14
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• 2019

A marine turning gear controls the position of the piston-crank mechanism by rotating the flywheel of the marine engine at a low speed, which is the main auxiliary machine that enables the disassembly and maintenance of the engine. In this study, the safety factor for surface durability and tooth bending strength was improved by the design modification of the marine turning gear based on the spur planetary gear. Angular velocity, torque, and efficiency of the turning gear were measured using a reliability evaluation tester, and a multibody dynamics model for analysis corresponding to the test results was developed. Finally, it was confirmed that the design improvements improved the tooth surface damage of the sun gear in the 3^rd reduction stage.

• Korean Journal of Materials Research
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• v.9 no.8
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• pp.810-816
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• 1999

The variations of crystalline structures and physical proerties of serpentine and talc mineral which was treated in a planetary ball mill, wre investigated by means of X-ray diffraction, FT-IR, DSC-TG, particle size analysis and SEM observation. The crystalline peaks of serpentine and talc in the XRD patterns were gradually reduced with the increase of grinding time and after 120 minutes turned into the amorphous phase, which is attributed to the disordering of the local structure around magnesium. The endothermic peaks for the ground serpentine and talc sample are observed at a considerably lower temperatures than that for the starting sample. A morphological change from the originally flat and irregular shape to spherically agglomerated particles was clearly observed.

• Journal of the Korean Society of Clothing and Textiles
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• v.19 no.2
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• pp.356-365
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• 1995

study was made to investigate the emulsification and rolling-up between liquid oily soils and surfactant and its effect on the detergency. Samples used were triolein as a triglyceride, oleic acid as a free fatty acid and sodium dodecyl sUJfate(SDS) as a surfactant. The results were as follows: 1. The spontaneous emulsification occurred in the system of oleic acid alone and mixture of triolein and oleic acid contacted with 0.5% SDS solution, but it did not occurred in a case of triolein alone. 2. The stability of emulsification increased with the increase of SDS concentration. And the stability of emulsification and (-) t value increased in the order of triolein < mixture of triolein and oleic and< oleic acid. 3. The rolling-up mechanism of model oily soils easily occurred in the order of triolein< mixture of triolein and oleic acid< oleic acid, and facilitated with the increase of SDS concentration. On the other hand, the complex formation was already observed in the system of oleic and 0.5% SDS solution. 4. As compared with the detergency of triolein, the detergency of oleic acid was very high. And the detergency of mixed soil was improved with increasing ratio of oleic acid in the mixture.

• Proceedings of the KSPS conference
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• 1994.02a
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• pp.45-53
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• 1994

음 변화 규칙을 음성규칙(A)와 음운규칙(B)와 기타(C)로 분류한다면, A.음성규칙의 발생 총계는 B.음운규칙의 발생 총계보다 2배 이상 더 많다. 여기에 가장 발생 빈도가 높은 규칙부터 순서대로 10개만 정리하면 다음과 같다. 순위 규칙부류 명칭 백분율 1 A 음절 말 유성자음의 불파화 31.84, 2 A 유성음화 19.37 3 B 장모음화 10.00, 4 A 설측음화 9.78, 5 B 경음화 6.43, 6 B 음절말 장애음 중화 5.16, 7 A ㅅ 구개음화 3.71, 8 C 음절 조정 규칙 3.10, 9 B 단모음화 1.60, 10 A ㄴ 구개음화 1.42 별도로 진행한 총체적 연구(이상억에 의하면, 음성규칙, 즉 A가 총 6개 있는데 그 중 5규칙이 10위 내에 나타나 상위 쪽에 3번이나 포함되어 있는 점이 주목된다. 특히 규칙 1과 2의 합계는 전체 중 51.2%를 넘는다. 규칙 10위까지의 합계는 전체 중 92.4%를 차지한다. 13.장모음화(10%)는 12.단모음화(1.6%)보다 훨씬 높은 출현빈도를 보인다. 또 각종 구개음화 규칙의 순위는 ㅅ(7위), ㄴ(10위), ㄹ(17위), ㄷ(26위) 구개음화로 분포되어 있음이 밝혀졌다. 한편 삭제규칙(음운탈락 및 단순화) 계열이 14, 15, 19, 21, 25, 28위에 널리 나열되어 있는 데 반해, 삽입규칙은 23위에 ㄴ삽입 하나가 보일 뿐이다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.7
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• pp.549-554
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• 2014

In general, there has been a lot of research concerned about the gear noise known to be proportional to gear transmission error for external gears likewise spur, helical gear, and hypoid gears. But, In the case of planetary gear set, gear noise study is insufficient because of the difficulty of designing, manufacturing, and understanding of its mechanical system. This study is aimed to develop the transmission error measurement equipment for the planetary gear sets used in the automatic transmission. By comparing the results of the transmission error and noise objectively, user could select the optimized planetary gear set which has quiet noise level before manufacturing the automatic transmission.

• Research in Plant Disease
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• v.8 no.1
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• pp.41-44
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• 2002

Two species of Phytophthora were isolated from infected fruits of jujube. Among 18 isolates collected, 6 were identified as P. nicotianae and 12 as P. patmivora on the basis of their mycological characteristics. The former produced no caduceus, ovoid to spherical sporangia in contrast to caduceus, ellipsoid, and broadly avoid to spherical ones of the latter. These two species were shown to be heterothallic and markedly papilate, chlamydospores abundant, and Al mating type. They skewed strong pathogenicity to fruits of jujube and pear while no symptom was produced on apple fruit by artificial inoculation. This is the first report of juiube fruit rot caused by P. ninotianae and P. palmivora in Korea.

• The Journal of Engineering Geology
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• v.4 no.2
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• pp.219-229
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• 1994

Since groundwater flow in fractured rocks is controlled by the distribution of fractures irregu1arly developed in space, it is not possible to understand the hydraulic characteristics of fractured aquifers using Theis equation which is applicable only to homogeneous isotropic confined aquifer. This study deals with the theoretical background of the fractal groundwater flow model with leakage, the methodology of calculation of the hydraulic parameters, and the application of the developed model to field data. From the result of the application of the fractal model to two field data in Hongcheon and Yusung areas, we obtained a good match between theoretical curves and observed curves, with the same hydraulic parameters at the pumping well and the observation well. In the two pumping test analyses, we have determined 1.9 of the fractal dimension. This means that the dimension of groundwater flow at these two sites is slightly smaller than radial flow.

• Publications of The Korean Astronomical Society
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• v.27 no.5
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• pp.411-418
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• 2012

We study the correlation between distributions of astronomical records and historical events using historical meteor (shower) records. In Korean chronicles, planets and meteor (shower) records are the most abundant astronomical phenomena. And they represent a general tendency of the number distribution of whole astronomical observations. We examine the correlation for the number distribution between meteors (showers) and planets during A.D. 1200-1700 and find that both records have a similar distribution. We classify historical events into three grades according to the social impact, and investigate the correlation between distributions of meteor (shower) records with social events, such as, new king's accession to the throne, foreign invasions, and domestic turmoils. From the statistical analysis, we cannot find any correlation between the meteor (shower) records and the political events. Therefore, we conclude that Korean historical records have not been influenced by the political events. We also examine the correlation between Chinese and Japanese meteor (shower) records and political events for A.D. 1200-1700, respectively, but cannot find any correlations between them.

• Nuclear Engineering and Technology
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• v.27 no.5
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• pp.661-669
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• 1995

A mobile robot, named KAEROT, has been developed for inspection and maintenance operations in nuclear facilities. The main feature of locomotion system is the planetary wheel assembly with small wheels. This mechanism has been designed to be able to go over the stairs and obstacles with stability. This paper presents the inverse kinematic solution that is to be operated by remote control. The automatic stair climbing algorithm is also proposed. The. proposed algorithms generates the moving pathes of small wheels and calculates the angular velocity of 3 actuation wheels. The results of simulations and experiments are given for KAEROT peformed on the irregular stairs in laboratory. It is shown that the proposed algorithm provides the lower inclination angle of the robot body and increases its stability during navigation.