• 한국자동차공학회논문집
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• 제13권4호
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• pp.145-151
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• 2005

Natural gas is one of clean fuels that can replace petroleum-based fuels, because it has low exhaust emission, comparatively high thermal efficiency and abundant deposits. In this addition, owing to high octane number and wide lean flammability limit, it has a strong point to increase the compression ratio. For this reason, the research is being actively executed to increase the generating power and thermal efficiency of the engine by raising the compression ratio through utilization of high octane number relevant to development of CNG engine. In this study, 0.63L single cylinder diesel engine has been used to alter easily compression ratio. Compression ratio has gotten under control by modifying the thickness of gasket between cylinder head and block without major structural modifications. As the result, as compression ratio has increased, generating power and fuel consumption ratio have been improved. As for emission concentration, as compression ratio has increased, THC concentration has been decreased while exhause concentration of NOx increased. In case compression ratio has excessively increased, brake output decrease and cycle variation have been increased. As the result acquired by analyzing brake output, fuel consumption ratio, cycle variation and exhaust, the engine driving condition has acquired $\varepsilon=13$ as the optimal compression ratio in this study.

• International Journal of Industrial Entomology and Biomaterials
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• 제34권2호
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• pp.23-31
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• 2017

Bumblebees, more efficient than honeybees, provide important services for pollination especially in tomato, pepper, cucumber, strawberries and other crops grown under tunnel farming or glasshouse conditions to yield maximization. These bees require pollen and nectar to meet their dietary needs and maintain their colony structure, development and reproduction. Keeping in view their economic importance, the effect of five concentrations of sugar and honey solutions (1:1, 1:1.5, 1:2, 2:1,1.5:1) each as alternative to nectar were used to observe their effect on life history parameters of Bombus terrestris. The 1:1 ratio of sugar solution was found most effective followed by 1.5:1, 1:1.5, 1:2 and 2:1 and also more effective of all five concentrations of honey solutions on all three stages of colony development i.e., at colony initiation, colony development and colony maturation stages. At colony initiation stage, early pre-oviposition period ($6.40{\pm}0.97$ days), early emergence of first worker in the first batch ($25.40{\pm}1.21$ days) and maximum numbers of workers ($6.20{\pm}0.24$) emergence in the first batch were observed at 1:1 ratio of sugar solution. Colonies reared on 1:1 ratio of sugar solution reached earlier ($52.13{\pm}1.28$ days) at colony foundation stage with minimum mortality ($3.27{\pm}0.54$ workers). At colony maturation stage, maximum numbers of workers, sexual (males, queens) and maximum mother queen longevity was observed at the same 1:1 ratio of sugar solution. It can be suggested from present study that sugar solution as alternative of nectar at 1:1 ratio was better than other sugar concentration levels and also from those of honey solution.

• Asian-Australasian Journal of Animal Sciences
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• 제27권10호
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• pp.1411-1416
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• 2014

Gender selection is important in livestock industries; for example, female calves are required in the dairy industry. Sex-sorted semen is commonly used for the production of calves of the desired gender. However, assessment of the sex ratio of the sorted semen is tedious and expensive. In this study, a rapid, cost effective and reliable method for determining the sex ratio was developed using a multiplex real-time polymerase chain reaction (PCR) assay. In this assay, the X and Y chromosome-specific markers, i.e., bovine proteolipid protein (PLP) gene and sex-determining region Y (SRY) were simultaneously quantified in a single tube. The multiplex real-time PCR assay was shown to have high amplification efficiencies (97% to 99%) comparable to the separated-tube simplex real-time PCR assay. The results obtained from both assays were not significantly different (p>0.05). The multiplex assay was validated using reference DNA of known X ratio (10%, 50%, and 90%) as templates. The measured %X in semen samples were the same within 95% confidence intervals as the expected values, i.e., >90% in X-sorted semen, <10% in Y-sorted semen and close to 50% in the unsorted semen. The multiplex real-time PCR assay as shown in this study can thus be used to assess purity of sex-sorted semen.

• 대한수의학회지
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• 제52권2호
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• pp.83-87
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• 2012

The study of pigs as a human disease model has been conducted in neuroscience. But the morphological development of pig brain by using MRI is rare. The purpose of this study is to determine whether cerebellum maintains consistent proportion to other brain regions in aging. Clinically healthy sixteen micropigs, 1, 2, 4, and 8 months were studied. The micropigs were anesthetized with isoflorane. MRI was acquired using a 0.3T system. To figure out development of ratio that allowed identification of normal cerebellum size, we measured the area of the cerebellum, brainstem, and forebrain from the mid-sagittal brain images on T1W. Mid-sagittal cross-sectional area (CSA) of total brain, forebrain, brainstem, and cerebellum were expressed as absolute values and also as percentages which were compared between the four age groups of micropigs for the purpose to define the effect of age on brain morphometry. It was found that there was not a significant difference in the percentage of the brain occupied by an individual region between groups although the absolute CSA differed significantly among age groups. There was no effect of age on the ratio between the cerebellum and total brain in 4 age groups. The normal size of cerebellum changes during brain development maintained a consistent ratio to other brain regions in normal micropigs. The ratio of CSA quantified on the mid-sagittal MR images offers a suitable method to detect presence of cerebellar anomalies in micropigs.

• Elastomers and Composites
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• 제50권2호
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• pp.103-109
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• 2015

In this study, epoxy/anhydride mixing ratio for the highly silica filled compounds with chromium (III) octoate catalyst was investigated at a low curing temperature ($71^{\circ}C$ for 40 hr) by evaluating the compressive strength with the weight ratio ranges from 0.3/1.0 to 1.0/1.0 of epoxy part (Part A)/anhydride part (Part B). In case of epoxy/anhydride compounds used surface unmodified silica by coupling agent, these compounds need excess anhydride unlike the weight ratio in the conventional epoxy/anhydride compounds. In curing behavior, the epoxy/anhydride compounds containing chromium (III) octoate showed high conversions at $71^{\circ}C$ for 40 hr, even if a dipropylene glycol (DPG) was not used as a polymerization initiator. Also, DPG leads to a poor epoxy network structure. In conclusion, the appropriate weight ratio of Part A/Part B of highly silica filled epoxy/anhydride compounds with chromium (III) octoate catalyst is 0.5/1.0 and the maximum amounts of silica is 1470 phr of epoxy resin.

• 접착 및 계면
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• 제2권4호
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• pp.32-38
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• 2001

본 실험에서는 공가류와 내오존성을 동시에 만족하는 고무 조성비의 영향에 대하여 검토하였다. 사용한 시편은 NR, SBR, BR, IIR 및 EPDM을 다양한 비율로 블렌딩 한 고무 조성물(시편 A), NR/BR/SBR로 구성된 불포화 고무 조성물(시편B)와 NR/IIR/EPDM로 구성된 포화 고무 조성물(시편C)이다. 시편A와 시편B, 시편A와 시편C를 각각 공가류시켜 PAD 접착 시편을 제작하여 박리강도를 측정하였다. 또한 시편A에 대해서 내오존성을 평가하였다. 시편 A의 불포화 고무 조성중(NR/BR Blend)에 BR보다 NR의 비율이 높을수록 시편B와 시편C와의 접착 강도가 높았고, 또다른 불포화 고무 조성(NR/SBR)에서는 NR보다 SBR 함량이 높을수록 접착 강도는 높았다. 또한 시편A의 조성중에서 NR/BR/IIR/EPDM 조성물 보다 NR/SBR/IIR/EPDM 조성물이 접착성이 우수하였다. 고무 조성중 불포화 고무가 많을수록 접착 강도는 우수하였으나, 내오존성은 다소 열세였다. 불포화 고무와 포화 고무의 비율이 60/40 정도 일 때 접착 강도와 내오존성이 모두 양호하였다.

• Fisheries and Aquatic Sciences
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• 제10권4호
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• pp.191-195
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• 2007

The aim of this study was to assess whether size-rank at the juvenile stage is associated with growth performance and sex ratio in olive flounder (Paralichthys olivaceus). Juveniles (mean body weight, $8.8{\pm}0.9\;g$) were selected from two age groups, with the high size-rank group (HSRG) fish in the upper 19.3-67.3% of 104 days post-hatching (dph) age group and the low size-rank group (LSRG) fish in the lower 9.0-55.7% of 116 dph age group. Triplicate groups of 100 fish were reared over 32 weeks. A heavier final body weight was observed in the HSRG ($360{\pm}12\;g$) compared to the LSRG ($315{\pm}9\;g$, P<0.05), whereas no differences in feed intake, feeding efficiency, and mortality were seen between the experimental groups. The percentage of females was significantly higher in the HSRG (51.7%) than in the LSRG (30.8%, P<0.05). In addition, a remarkable increase in growth was recorded in females, indicating that the relative frequency of females increased with a body weight increase. The results suggest that high size-rank juvenile olive flounder have better growth performance and a higher percentage of females, because females start growing faster than males before size grading occurs.

• 한국농공학회논문집
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• 제61권3호
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• pp.15-22
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• 2019

In order to preserve water environment, Total Maximum Daily Load(TMDL) is used to manage the total amount of pollutant from various sources, and the annual average load of source is calculated by the unit load method. Determination of the unit load requires reliable data accumulation and analysis based on a reasonable estimation method. In this study, we propose a revised unit load estimation method by analyzing the unit load calculation procedure of National Institute of Environment Research(NIER) method. Both methods were tested using observed runoff ratio and water quality data of rice paddy fields. The estimated values with the respective NIER and revised NIER methods were highly correlated each other. However, the Event Mean Concentration(EMC) and the runoff ratio considered in the NIER method appeared to be influenced by rainfall classes, and the difference in unit load increases as the runoff and EMC increase. The error can be further increased when the EMC and runoff ratio are changed according to changes in rainfall patterns by climate change and change of agricultural activities. Therefore, it is recommended to calculate unit load by applying the revised NIER method reflecting the non point pollution runoff characteristics for different rainfall classes.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.365-370
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• 1997

In this paper we suggest a development of surface defect inspection algorithms for cold mill strip using tree structure. The defects which exist in a surface of cold mill strip have a scattering or singular distribution. This paper consists of preprocessing, feature extraction and defect classification. By preprocessing, the binarized defect image is achieved. In this procedure, Top-hit transform, adaptive thresholding, thinning and noise rejection are used. Especially, Top-hit transform using local min/max operation diminishes the effect of bad lighting. In feature extraction, geometric, moment, co-occurrence matrix, histogram-ratio features are calculated. The histogram-ratio feature is taken from the gray-level image. For the defect classification, we suggest a tree structure of which nodes are multilayer neural network clasifiers. The proposed algorithm reduced error rate comparing to one stage structure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.169-174
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• 2001

This paper reports on the development of high aspect ratio structure and 3-D integrated process for MEMS-based micro gas turbines. To manufacture high aspect ratio structures, Deep Reactive Ion Etching (DRIE) process have been developed and optimized. Specially, in this study, structures with aspect ratios greater than 10 were fabricated. Also, wafer direct bonding and Infra-Red (IR) camera bonding inspection systems have been developed. Moreover, using glass/silicon wafer direct bonding, we optimized the 3-D integrated process.