• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.1 s.256
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• pp.1-10
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• 2007

This paper presents a design guidance of jig/fixture for flexible manufacturing system based on the verification of a base assembly motion instability. In flexible assembly system, the base assembly needs to be maintained in its assembled state without being taken apart. This requires stability in motion while the base assembly is handled or tilted. Therefore, the instability of the base assembly motion should be considered when determining the guide line of designing jig/fixture by evaluating a degree of the motion instability of the base assembly. To derive the instability, first we inference collision free assembly directions by extracting separable directions for the mating parts and calculate the separability which gives informations as to how the parts can be easily separated. Using these results, we determine the instability evaluated by summing all the modified separabilities of each component part within base assembly.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.395-401
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• 2003

In this paper, the dent printing phenomena and critical dent size which lead to premature failure of deep grooved ball bearing for automobiles are presented. The results of newly assembled test bearings showed that the ball dent size strongly affect the bearing life and inner ring raceways were the major failed parts in spite of using the dented balls. The dent printing phenomena are a root cause of premature failure, which was not reported until now. And there exist the critical ball dent size for given rolling bearings and operating conditions. So, the initial condition of tribologically mating parts should be treated as important as the failed body itself.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.1
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• pp.132-141
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• 1995

This paper presents a choosing method of turning devices for stable robotic assembly based on verification of a base assembly motion instability. In flexible assembly application, the base assembly needs to be maintained in its assembled state without being taken apart. Therefore, the instability of the base assembly motion should be considered when determining the guide line of choosing turning devices by evaluating a degree of the motion instability of the base assembly. To derive the instability, first we inference collision free assembly directions by extracting separable directions for the mating parts and calculate the separability which gives informations as to how the parts can be essily separated. Using these results, we determine the instability evaluated by summing all the modified separabilites of each component part within base assembly.

• International Journal of Industrial Entomology and Biomaterials
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• v.18 no.1
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• pp.41-48
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• 2009

The large bumblebee, Bombus terrestris, indigenous to Europe and used extensively for high-value crop pollination, has been artificially introduced in several parts of the world. Here we show the interspecific hybridization between bumblebee species, B. terrestris and B. ignitus, under laboratory conditions. The mating and oviposition percentages of the interspecific hybridization of a B. terrestris queen with a B. ignitus male were higher than those of the intraspecific mating of B. ignitus. Furthermore, the competitive copulation experiment indicated that the mating of B. ignitus males with B. terrestris queens was 1.8-fold more frequent than with B. ignitus queens. The interspecific hybridization of a B. ignitus queen with a B. terrestris male produced either B. ignitus workers or the B. ignitus male phenotype, and the hybridization of a B. terrestris queen with a B. ignitus male produced B. terrestris males. Genetic tests using a portion of the mitochondrial COI gene for the parent and hybrid phenotypes indicated that mitochondrial DNA in the interspecific hybridization was maternally inherited. Our results indicated that interspecific hybridization occurred between B. ignitus and B. terrestris, which suggests that the hybridization will have a negative impact of competition and genetic pollution of native bumblebees.

• The Korean Journal of Physiology
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• v.8 no.1
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• pp.15-22
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• 1974

The influence, upon male rat's mating behavior, of Korean Panax Ginseng administered for 3 and 5 days was investigated by direct behavioral observation and also by counting the number of copulation plugs the animals deposited. Four쇼-four male albino rats were used. Part of the animals received ginseng for 3 days (ginseng-3 day group, N= 12) or for 5 days(ginseng-5 day group, H=10), while the remaining animals received saline for 3 days (saline-3 day group, N=12) or for 5 days (saline-S day group, N=10). Each animal belonging to the 2 ginseng groups received subcutaneously 0.5 ml/100 g body weight of ginseng alcohol extract solution (4 mg of the ethyl alcohol extract in 1 ml of physiological saline), and each rat belonging to the 2 saline groups received the same amount of saline per day. During the dark period of the light-dark cycle on the next day following the last drug administration, a female rat in the artificial estrus was introduced to each male and the mating behavior was observed for 45 minutes. The observation session was divided into two parts and, in the early part which terminated with the first ejaculation and succeeding intromission, following behavioral measures were taken: mounting latency, intromission latency, inter-intromission period, ejaculatory latency(time from the first intromission until the first ejaculation), occurrence of mounting with intromission, occurrence of mounting without intromission, and postejaculatory interval. Behavioral measures taken in the later part of the session after the first ejaculation were: occurrence of mounting with intromission, occurrence of mounting without intromission, and occurrence of ejaculation. Immediately after the behavioral observation session the experiment turned to measure, for 10 days, the number of copulation plug which each pair of rats deposited. Following results were obtained: 1. After several mountings mounting with intromission, males of the 2 ginseng groups finished the first ejaculation significantly earlier than the corresponding 2 saline groups did. 2. The postejaculatory latency was significantly reduced in the ginseng-5 day group compare with the value of the saline-5 day group and also compared with the value of the ginseng-3 day group. 3. The 2 ginseng groups ejaculated significantly more often in 45 minutes' observation session than the corresponding 2 saline groups did. 4. The number of copulation plug deposited in 10 days by the animals of the 2 ginseng groups. significantly exceeded the number deposited by the corresponding 2 saline group animals. The animals of the ginseng-5 day group deposited copulation plugs significantly more than the animals of the ginseng-3 day group did. It is inferred from the above results that the ginseng facilitates mating behavior of male rats, and that the degree of facilitation may be influenced by the duration of drug administration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.35-46
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• 2013

A parametric modeling method, one of the core technology of BIM (Building Information Modeling), is proposed for efficient 3D assembly design among components of a superstructure module of modular steel bridge. Assembly system is classified into 3 levels as LoD (Level of Details) for 3D assembly design of the parts. Components forming 3D shape of the parts are identified and defined as parameters, variables depending on parameters, or constants independent of the parameters. Then, spatial assembly rules among the parts are defined according to the assembly system. Positional relations among the identified shape components are defined for mating spatial position and geometrical relations are defined for constraining degree of freedom on X, Y, and Z axis. Finally, a standardized template is designed by applying the rules to 3D based assembly design for the parts of the superstructure module. In addition, applicability of the parametric modeling method is demonstrated by testing the shape variation of the superstructure module according to changing the defined parameters.

• Korean Journal of Environment and Ecology
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• v.35 no.6
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• pp.594-600
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• 2021

The purpose of this study is to observe the period of mating calls of cicadas in South Korea to identify the emergence period and geographic distribution for each cicada species. The study sites were 19 protection areas nationwide. The mating calls of cicadas were collected over the 12 months of 2019. A bioacoustics measuring device was installed to record the mating calls of cicadas in WAV, 44,100Hz format for 1 minute every hour. The temperature was recorded once or twice every hour using a micro-meteorological measuring device. Nine species of Korean cicadinae were studied. The start and end periods of mating calls were recorded for each cicada species for the subsequent analysis. The analysis results showed that nine cicada species appeared in the 19 protection areas. The chronological order of mating call periods for each species was as follows: Cryptotympana atrata (7/12 - 9/30), Meimuna opalifera (7/27 - 10/20), Hyalessa fuscata (7/25 - 10/9), Graptopsaltria nigrofuscata (7/28 - 9/5), Platypleura kaempferi (7/3 - 9/29), Suisha coreana (9/14 - 10/30), Leptosemia takanonis (6/26 - 8/2), Auritibicen intermedius (7/27 - 9/28), and Meimuna mongolica (8/8 - 9/11). The mating call period was between 35 (Meimuna mongolica) and 89 (Platypleura kaempferi) days, with the average being 62 days. The elevation above sea level for the habitats of each species was as follows: 5 - 386 m for Cryptotympana atrata, 7 - 759 m for Meimuna opalifera, 7 - 967 m for Hyalessa fuscata, 42 - 700m for Graptopsaltria nigrofuscata, 7 - 700 m for Platypleura kaempferi, 5 - 759 m for Suisha coreana, 7 - 759 m for Leptosemia takanonis, 397 - 967 m for Auritibicen intermedius, and 7 - 42 m for Meimuna mongolica. The average temperature of the habitats of each species was as follows: 23.9℃ for Cryptotympana atrata, 21.8℃ for Meimuna opalifera, 22℃ for Hyalessa fuscata, 23℃ for Graptopsaltria nigrofuscata, 22.9℃ for Platypleura kaempferi, 14.6℃ for Suisha coreana, 20.6℃ for Leptosemia takanonis, 19.3℃ for Auritibicen intermedius, and 24.4℃ for Meimuna mongolica. In terms of the habitat distribution of species, Meimuna opalifera, Hyalessa fuscata, and Platypleura kaempferi were distributed in more than 15 protection sites. Cryptotympana atrata was distributed in the lowlands in the southwest. Graptopsaltria nigrofuscata was distributed in the western area of the Korean Peninsula. Suisha coreana was distributed in areas excluding high mountain areas and parts of the southeast area. Leptosemia takanonis was distributed in areas near the mountains. Auritibicen intermedius was distributed locally in the high mountain areas. Meimuna mongolica was distributed locally in flat wetlands.

• Korean Journal of Computational Design and Engineering
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• v.10 no.2
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• pp.133-142
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• 2005

This paper proposes an object-oriented conceptual information model of mechanical assemblies, named open assembly model (OAM). The proposed assembly model primarily defines hierarchical relationships between parts and subassemblies. Together with the assembly hierarchy. the model also provides a way to represent tolerances, kinematic information, and parametric assembly constraints. Relational information such as mating conditions and degree of freedom between parts and subassemblies is captured via assembly features and relationships thereof. The information model is described using class diagrams of the Unified Modeling Language (UML), and instance diagrams are used to exemplify the proposed information model. The conceptual model presented in this paper is an integrated information model for assembly representation, which could supply necessary information for tolerance analysis and synthesis, kinematic simulation, and assembly simulation. Such a conceptual information model plays an important role for the exchange of information between modeling, analysis and planning systems. Hence, the proposed model could serve as a framework for developing data exchange standards of mechanical assemblies. The proposed model is demonstrated through a case study of a planetary gear assembly.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.95-96
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• 2002

The operation of proceeding bearing in the conditions of misaligned axis of proceeding and bush leads to the load concentration on the bearing edges causing further mixed lubrication conditions, unstable operation and intensive wear of mating parts. For the design process of proceeding bearing the knowledge of static characteristics determined from the oil film pressure and temperature distribution is very important. For the 3-lobe proceeding bearing, the pressure, temperature and viscosity fields, load capacity, minimum oil film thickness, power loss, oil flow and maximum oil film temperature have been determined by iterative solution of the Reynolds', energy and viscosity equations. The paper introduces the results of theoretical investigations of static characteristics of 3-lobe proceeding bearing operating at misaligned axis of proceeding and bush. An effect of misalignment ratio, length to diameter ratio of the proceeding bearing, the lobe clearance ratio on the static characteristics was investigated. Laminar, adiabatic model of oil film for the solution of Reynolds, energy and viscosity equations was applied.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.71-74
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• 2005

More than five pulleys are used in an automobile, such as crankshaft, water pump, air-con compressor, fan and power steering pump pulley. These pulleys are parts that need durability until retiring a car. But there is no design criterion for durability, so pulleys are designed by the experience of designer and trial and error. So, in this study, we carried out stress analysis at durability test condition and compared analysis results to durability test results. It is found that the design criterion for durability is defined as a safety factor and a safety factor is different according to the distance between the center line of v-grooves and the mating surface.