• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1533-1538
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• 2011

The dynamic characteristics such as resonant frequencies and dampings have been utilized as important parameters in dynamic behavior and inverse analyses. In general, the dynamic parameters have been determined based on design and experimental data, but experimental studies on the time-dependent changes of the dynamic parameters during service have rarely been conducted. Especially, unlike highway bridges, it is much easier for railroad bridges to estimate accumulated amount of fatigue because of the controlled train operation, and the study of dynamic characteristic change due to fatigue is useful, since it can enhance the accuracy of dynamic analysis. In this paper, the dynamic characteristic change due to fatigue is measured via the modal test on the PSC girder during a fatigue test. The test specimen utilized in the test is the IT girder which enhances the sectional capacity of the conventional PSC girders. The test specimen is designed 10m long and the modal tests are conducted during the application of fatigue load two million times. The test result shows that considerable changes in the measured dynamic parameters are observed as the fatigue accumulates, and these changes during the service life should be considered in designing railroad bridges.

• 동력기계공학회지
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• 제16권6호
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• pp.66-72
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• 2012

The parking brake embedded in track driving motor for driving an excavator is composed of wet type multi-friction discs. This type parking brake can be designed more compact because the combination of some sheets of friction discs generate great braking power, and also it has good braking characteristic and long life time because it works in the oil. In this study, we analyzed torque characteristic of the parking brake through simulations and performed experiments by use of 3-kinds of paper friction sheet manufactured by different pressing methods. And, we compared the maximum static friction coefficient and torque characteristic with the simulation results and confirmed the optimal manufacturing process through this result.

• Journal of Power Electronics
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• 제16권4호
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• pp.1268-1276
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• 2016

A triode for alternating current (TRIAC) dimming light emitting diode (LED) driver, which adopts a variable switched capacitor for LED dimming and LED power regulation, is proposed in this paper. The proposed LED driver is power efficient, reliable, and long lasting because of the TRIAC switch that serves as its main switch. Similar to previous TRIAC dimmers for lamps, turn-on timing of a TRIAC switch can be controlled by a volume resistor, which modulates the equivalent capacitance of the proposed variable switched capacitor. Thus, LED power regulation against source voltage variation and LED dimming control can be achieved by the proposed LED driver while meeting the global standards for power factor (PF) and total harmonic distortion (THD). The long life and high power efficiency of the proposed LED driver make it appropriate for industrial lighting applications, such as those for streets, factories, parking garages, and emergency stairs. The detailed analysis of the proposed LED driver and its design procedure are presented in this paper. A prototype of 80 W was fabricated and verified by experiments, which showed that the efficiency, PF, and THD at V_s = 220 V are 93.8%, 0.95, and 22.5%, respectively; 65 W of LED dimming control was achieved with the volume resistor, and the LED power variation was well mitigated below 3.75% for 190 V < V_s < 250 V.

• Animal Systematics, Evolution and Diversity
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• 제34권3호
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• pp.152-158
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• 2018

Two new records of spionid polychaetes, Prionospio pulchra Imajima, 1990 and Scolelepis (Scolelepis) sagittaria Imajima, 1992, collected from Korean waters are reported here with detailed descriptions and illustrations. Prionospio pulchra can be distinguished from its relatives by remarkably long and apinnate branchiae, the first chaetiger with notopodial chaetae, and the presence of ventral sabre chaetae. Scolelepis (Scolelepis) sagittaria is characterized by a sagittate prostomium, an occipital tentacle, and bi- or tridentate hooded hooks. In this paper, photographs of scanning electron microscopy for characteristic features of each species are presented. Keys to Prionospio and Scolelepis species from Korean waters are also provided.

• 생명과학회지
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• 제9권4호
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• pp.341-347
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• 1999

Insects use chitinolytic enzyme to digest chitin in the exoskelton during the molting process. We have isolated and sequenced a chitinase-encoding cDNA from the silkworm, Bombyx mandarina, compared its sequenced with genes encoding chitinolytic enzymes from other sources. The insert DNA in the clone is 2,675 nucleotides long with an open reading frame of 1,695 uncletides that encodes a protein of 565 amino acids with a molecuar weight of 63.4 kDa. The 3' -untranslated region of 889 nucleotides is AT-rich and contains two putative polyadenylation signals. The N-terminal sequence of the encoded protein contains numerous hydrophobic residues characteristic of a leader peptide. The amino acid alignment revealed that the endo-$\beta$-N-acetylglucosaminidase had 83% and 97% homology with M. sexta and B. mori, respectively. The deduced amino acid had two highly conserved region at the amino acid residues 97-111 and 139-148 that were related to the existing chitinase.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.339-341
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• 2002

The remaining life of ACSR exposed to the atmosphere for a long period may rely on deterioration caused by environmental indices such as atmospheric corrosion, galvanic corrosion, crevice corrosion and fatigue corrosion. One of reduction of useful life in overhead transmission lines built on the ridge of mountain is often caused by forest fires. This paper deals with investigation of strength deterioration performance of ACSR due to fires through several testing and analyzing data for both tension load and material analysis. Test samples are ACSR $480[mm^2]$ conductors, which are artificially fired to regular durations. As a result, it can be verified that tension load of ACSR are reduced by increasing fro duration. Hence, it is obvious that ACSR due to forest fires may lead to mechanical deterioration.

• Asian-Australasian Journal of Animal Sciences
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• 제13권9호
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• pp.1337-1344
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• 2000

Differences in the physical structure and chemical composition of sorghums result in different nutritional values. Sorghums with high in vitro nutrient digestibility tend to have greater ileal and total tract nutrient digestibilies. Soft endosperm can improve growth and nutrient digestibility in nursery pigs and broiler chicks. However, finishing pigs respond less to endosperm hardness. Chicks benefit from waxy sorghums, but responses of swine to waxy sorghum remain controversial. Reduction of particle size benefits nursery pigs more than finishing pigs, while age of chicks affects the coarseness preference. Nutritional benefits of thermal processing in sorghum remain unclear in chicks and pigs. Although experiments have demonstrated increased efficiency with processed sorghum, processing provided only an immediate solution to the problem of reduced utilization. Long-term, solutions will be genetic improvement of physical and on chemical characteristic.

• 가정과삶의질연구
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• 제17권1호
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• pp.103-120
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• 1999

The purpose of this study was to investigate the characteristics and caregiving behavior in families who awarded on filial piety. Using the qualitative method 137 families and social supports to them were analyzed,. The major findings can be summarized as follows (1) Most of caregivers were daughter-in -law over 40 years in 3-generation or 2-generation family. Elderly can be characterized as oldest-old dependent long-term care for more than 10 years. (2) These families showed very high family solidarity with strong collectivity. (3) Their economic emotional and service cares were family-centered with helps from their extended family. These families were supported emotional helps rather than instrumental helps from social network. It was concluded that to help family elder care social support program for the frail elder caregiving families should be complemented in their children support program family life enrichment program for the inter-generational relationship medical care program other social network program and religion program etc. And more concrete and qualified study for the adaptation of filial piety families should be followed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.331-333
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• 2001

The flooded type battery is used for solar lighting system. Because the characteristic of flooded type battery is the short life time, the maintenance cost is high. So the using floe fed type battery in this system is inappropriate. The valve regulated lead acid batter(VRLA) is the maintenance free and cycle service purpose. This paper presents the development of control system and monitoring system to applied VRLA battery for maintenance free and long life time in system.

• 산업경영시스템학회지
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• 제37권2호
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• pp.70-76
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• 2014

In industrial situation, electronic and electro-mechanical systems have been using different type of batteries in rapidly increasing numbers. These systems commonly require high reliability for long periods of time. Wider application of battery for low-power design as a prime power source requires us knowledge of failure mechanism and reliability of batteries in terms of load condition, environment condition and other explanatory variables. Battery life is an important factor that affects the reliability of such systems. There is need for us to understand the mechanism leading to the failure state of battery with performance characteristic and develop a method to predict the life of such battery. The purpose of this paper is to develope the methodology of monitoring the health of battery and determining the condition or fate of such systems through the performance reliability to predict the remaining useful life of primary battery with load condition, operating condition, environment change in light of battery life variation. In order to evaluate on-going performance of systems and subsystems adopting primary batteries as energy source, The primitive prototype for performance reliability analysis device was developed and related framework explained.