• Asian-Australasian Journal of Animal Sciences
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• 제20권11호
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• pp.1761-1769
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• 2007

This experiment was conducted to determine the extent to which susceptibility to cortisol-induced follicle shutdown is influenced by fleece phentotype. Twenty Finewool (10 sheep low fibre diameter, low coefficient of fibre diameter-LL and 10 low fibre diameter, high coefficient of variation of fibre diameter-LH) and twenty Strongwool (10 low fibre diameter, low coefficient of variation of fibre diameter-HL and 10 high fibre diameter and high coefficient of variation of fibre diameter-HH) sheep of 9 months of age were individually penned in an animal house and were injected intramuscularly with an aqueous suspension of hydrocortisone acetate at a rate of 1.42 mg/kg body weight for a period of two weeks. Fibre diameter was measured from clipped tattooed patch wool samples. Follicle activity was measured by histological changes in skin biopsies taken weekly. Blood samples were collected at two-week intervals and plasma cortisol measured. Increased plasma cortisol concentration significantly (p<0.05) reduced clean wool production and mean fibre diameter dropped to its lowest level four weeks after commencement and two weeks after the cessation of cortisol injection. Elevation of plasma cortisol concentration significantly (p<0.0001) increased the percentage of inactive follicles two weeks after injection started. High fibre diameter groups (Strongwool sheep; i.e. HL+HH) had significantly (p<0.0001) higher percentage of follicle shutdown than low fibre diameter groups (Finewool sheep; i.e. LL+LH). Average percentage of shutdown follicles for Finewool (LL+LH) and Strongwool (HL+HH) Merino sheep was $9.8{\pm}0.9$ and $13.5{\pm}0.9$ respectively. Shutdown of primary follicles was more pronounced in Finewool than Strongwool sheep. There was no significant effect of coefficient of variation of fibre diameter on propensity to follicle shutdown induced by exogenous cortisol. It is concluded that elevation in plasma cortisol concentration is inhibitory to the normal activity of follicles in Strongwool sheep but that variation in fibre diameter has little or no effect.

• 소성∙가공
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• 제4권3호
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• pp.257-266
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• 1995

A simulation method based on upper bound method is developed in order to characterize forging characters in forging of spur gears. In this paper, utilizing a kinematically admissible velocity field and applying it to investigate the effect of inner diameter of holow billet. In the analysis, to predict the variation of inner diameter of hollw billet, neutral surface has been introduced. The neutral surface of each step is assumed as a circle and determined in order to have minimum forging energy by golden section method. By this method, the variation of inner diameter of billet during spur gear forging is successfully predicted. As a result, the selection of inner diameter of initial billet is very important to reduce the forging load.

• 한국자동차공학회논문집
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• 제8권3호
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• pp.18-27
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• 2000

The spray models incorporated into the GTT code were tested for free spray, spray in swirling flows and the sprays impinging on a flat wall. And the validity of the models has been confirmed by comparing the calculated results with the experimental data. Using this code, the spray behavior in the diesel combustion chamber have been numerically analyzed for variation of nozzle diameter. Also, the effects of nozzle diameter in diesel combustion was investigated experimentally by measuring the performance in a D.I engine. This study provides the information for the spray characteristics and emissions with variation of nozzle diameter. As a result, it has shown that decreasing nozzle diameter resulted in improving smoke and specific fuel consumption in a middle speed range.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제20회 KOSCO SYMPOSIUM 논문집
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• pp.35-44
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• 2000

It was numerically studied that NOx emission characteristics of confined $CH_{4}$ jet flames with the variation of the diameter of inner fuel nozzle, the flow rate of $CH_{4}$ and equivalence ratio. Parabolic type equations were adopted in the calculation and GRI-2.1I mechanism was used for the chemical reaction. NOx emission index (EINOx) was introduced to evaluate NOx emission quantitatively in parametrically varied flames and the contribution of Thermal and Prompt NO mechanism was discussed. The results showed that Total EINOx varied sensitively with the variation of the flow rate of$CH_{4}$ but it was not sensitive to the variation of the diameter of inner fuel nozzle. Thermal EINOx showed the similar tendency to total EINOx and Prompt EINOx showed insensitivity to the variation of the diameter of inner fuel nozzle and the flow rate of $CH_{4}$.

• 한국분무공학회지
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• 제18권3호
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• pp.126-131
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• 2013

This paper describes the effect of ultrasonic frequency(f) on the atomization and deformation characteristics of single water droplet in an acoustic levitation field. To achieve this, the ultrasonic levitator that can control sound pressure and velocity amplitude by changing frequency was installed, and visualization of single water droplet was conducted with high resolution ICCD and CCD camera. At the same time, atomization and deformation characteristics of single water droplet was studied in terms of normalized droplet diameter($d/d_0$), droplet diameter(d) variation and droplet volume(V) variation under different ultrasonic frequency(f) conditions. It was revealed that increase of ultrasonic frequency reduces the droplet diameter. Therefore, it is able to levitate with low sound pressure level. It also induces the wide oscillation range, large diameter and volume variation of water droplet. In conclusion, the increase of ultrasonic frequency(f) can enhance the atomization performance of single water droplet.

• 한국통신학회논문지
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• 제12권4호
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• pp.335-346
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• 1987

光纖維 內에서 後方散亂을 일으키는 주된 要因은 光纖維 構成物質의 密度 不均一과 코어變化에 의해 發生하는 Rayleigh散亂이다. 이 後方散亂에 의해 發生하는 後方散亂 光電力은 optical time domain reflectometer로 檢出할 수 있다. O.T.D.R. 시스템으로 檢出한 後方散亂 光電力은 光纖維 길이에 따른 電力減衰情報와 光纖維 코어의 直徑變化에 관한 情報들을 포함하고 있다 따라서 本 論文에서는 avalanche photodiode의 飽和狀態를 除去할 수 있는 2$\times$2fiber directional coupler와 S/N比를 增加시키는 gated integrato와 timing control circuit를 첨가하여 O.T.D.R. 시스템을 構成하였으며, 構成한 O.T.D.R 시스템으로 後方散亂 光電力을 檢出하여 光纖維 內 코어의 直徑變化를 測定하였다.

• 대한치과기공학회지
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• 제42권3호
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• pp.220-227
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• 2020

Purpose: This study aims to investigate the cusp variation pattern of the Korean mandibular second premolar and to determine the difference in tooth diameter and surface area using a virtual three-dimensional model. Methods: Dental casts from 69 students were scanned as a virtual dental models with a three-dimensional dental model scanner. Tooth diameter, absolute and relative individual areas, total crown area, the number of lingual cusps and central groove pattern were analyzed using RapidForm 2004. The Mann-Whitney U-test and the Kruskal-Wallis test were performed to verify sexual dimorphism, the difference in tooth diameter and surface according to the cusp variation pattern (α=0.05). Results: There was no significant difference except in buccolingual diameter (p<0.05) and buccolingual diameter at the cervix (p<0.05). The relative surface area of the total clinical crown was 65.76% for the buccal half and 34.24% for the lingual half, with a ratio of 2:1. In the case of the presence of two lingual cusps, the ratio was 21.47% for the mesiolingual half and 14.12% for the distaolingual half, with a ratio of 3:2. The dominant central groove patterns of the second premolar were the H-pattern (42.0%), followed by the Y-pattern (37.7%), then the U-pattern (20.3%). The relative buccal half was largest in the U-pattern central groove and the relative lingual half was largest in the Y-pattern central groove (p<0.05). Conclusion: This study is significant in that it measured quantitative surface areas and the findings could be a meaningful reference to comprehend dental anatomy in Koreans.

• 품질경영학회지
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• 제51권4호
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• pp.633-642
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• 2023

Purpose: The variation of the internal diameters of gun barrel incurs a lot of reworks in gun barrel manufacturing process and the significant quality problem of gun barrel. And it is likely to stem from the current measurement system for the internal diameter of gun barrel and the related manufacturing process as well. The purpose of this study is to improve the gun barrel manufacturing process through improving measurement system. Methods: The improved measurement system using laser can measure the internal diameters of gun barrel more accurately, and the properly adjusted honing process reduces the variation of internal diameters of gun barrel. Results: Comparing the mean square error of internal diameters for 6 gun barrels measured before and after process improvement shows that the variation of gun barrel internal diameters was significantly reduced after the process improvement. Conclusion: The introduction of improved measurement system for the internal diameters of gun barrel and the adjustment of related honing process results in the reduction of reworks of gun barrels and their internal diameter variations.

• Journal of the Korean Wood Science and Technology
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• 제15권3호
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• pp.14-23
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• 1987

This study was carried out to investigate the anatomical characteristics, the radial and axial variation of the cell dimension and bulk density for four bamboo species used as the major material of bamboo products in Korea; Phyllostachys(P.bambusoides, P.edulis, P.nigra var.henonis, and Pnigra). The results obtained were summarized as follows; 1) In the outer part of culm, the mophological difference of cell diameter and distribution were not acknowledged. However, gum-like substance was occurred In the epidermis, hypodermis, cortex and metaxylem vessel of P.nigra, while it was occured only in the metaxylem vessel of P.edulis. 2) The protoxylem vessel in the central zone of culm-wall could be in the two types; the first type consisted of 4-5 small cell pieces occurred in P.edulis and P.nigra var. henonis, the second type of 1-2 large cell pieces in P.bambusoides and P.nigra. And transition of cell diameter from the vascular bundle sheath to the ground tissue was gradually enlarged in P.nigra and P.edulis but abruptly in P.bambusoides and P.nigra var. henonis. 3) Thin-wall tyloses were well developed in the outer and central zone of culm-wall in four species. 4) Compared with the central part of culm-wall, the number of parenchyma cells and the amount of the vascular bundle sheaths per unit area were a few in the inner part. The inner part nearest to the pith cavity was consisted of thick-well parenchyma cell. 5) The dimensional variations of metaxylem vessel and parenchyma cell in the radial direction were decreased from the inner part to the epidermis in all species observed. 6) The fiber length was the maximum in the central zone and its diameter was increased from the inner part to the outer part. In the axial variation. fiber length was slightly increased from the base and then decresed slowly toward the top, and its diameter was reverse. 7) The axial variation of the bulk density was continuously increased from the base toward the top and its radial variation was rapidly increased from the inner part to the epidermis.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1598-1603
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• 2004

This paper is an experimental study on the performance characteristic with a variation of capillary diameter and length. The performance characteristic of a refrigeration system is predicted that it is occurring changes of flow pattern and pressure drop in a capillary tube because of reduction of capillary diameter 0.74 to 0.6 mm. The difference between experimental results and analytical results is mainly caused by values of friction factor for using to calculate pressure drop through a small diameter capillary tube under 0.74mm. The experimental equation is derived from capillary tube test data using curve fitting method.