• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 금형가공 심포지엄
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• pp.225-230
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• 2002

As in most metal forming processes, die and lubrication are of vital importance in hydrostatic extrusion. An efficient die design and lubrication system selection reduce the pressure required for a given reduction ratio by lowering friction at the billet-die interface. In contrast to the conventional macroscopic extrusion, fine-wire fabrication requires higher extrusion pressure and effect of friction is much more significant. Forming fine Au, Ag, and Cu wire with hydrostatic extrusion process in cold condition, the effect of extrusion die angle, lubrication and billet's initial diameter was studied.

• 대한기계학회논문집
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• 제11권3호
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• pp.376-385
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• 1987

본 연구에서는 평면응력 파괴인성치의 거동에 관한 일련의 연구로서 위와 같 은 점을 고려하여 얇은 두께의 시험편을 이용하여 z의 변화에 대한 평면응력 파괴인성 치와 J저항곡선을 실험적으로 고찰하였으며 크랙성장을 고려한 J적분식도 검토하였다. 크랙길이는 하중제거 컴플라이언스법에 의하여 구하였고, ASTM E813의 방법으로J= .sigma.$_{f}$ .DELTA.(2ａ)인 크랙둔화선과 J저항곡선의 교점에서 구한 J적분값을 J$_{c}$로 정 의하였다. 또한, 재료를 변형경화재료로 가정하여 HRR응력변형율장의 특성을 이용 하여 J적분값을 구한 후 실험치와 상호 비교 검토하였다.이때 입력자료는 실험치의 그것과 동일하게 하였다. 동시에 z의 변화에 대한 T의 변화도 함께 고찰하였다.다.

• 한국정밀공학회지
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• 제28권3호
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• pp.370-376
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• 2011

Recently, the application range of plastic gears is widely expanding by the development of engineering plastics with good mechanical properties. Plastic gears have excellent performances such as light weight, water resistance and vibration absorbing ability for metallic gears. In this study, the optimization of injection molding process was done for the large disk type plastic gears of auto phoropter. Design Of Experiment (Taguchi method) was adopted to find a tendency of molding conditions that influence the flatness of disk type gear. Four main factors for molding conditions were selected based on injection temperature, filling time, packing pressure and mold temperature. Also, Filling, packing and cooling analyses were carried out to evaluate Z directional deflection of large disk type gear by using the simulation software (Moldflow) based on the DOE. From the results, it was found that the injection temperature and packing pressure are the most sensitive parameters for the Z directional deflection of large disk type gears.

• Asian Journal of Atmospheric Environment
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• 제2권1호
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• pp.26-33
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• 2008

In order to fully understand the chemical properties of Asian dust particles, especially their transformation and aging processes, it is desirable to investigate the nature of original sands collected at local source areas in China. This study presents the detailed properties of sands collected at four different desert regions (Yinchuan, Wuwei, Dulan, and Yanchi) in China. Most of sands have irregular shape with yellowish coloration, whereas some of them show peculiar colors. The relative size distribution of sands collected at Yinchuan, Wuwei, and Dulan deserts exhibits monomodal with the maximum level between 200 and $300{\mu}$, whereas that of Yanchi desert is formed between 100 and $200{\mu}$. The mass concentration ratio of each element to that of Si (Z/Si) determined by PIXE analysis has a tendency towards higher Z/Si ratios for soil derived elements. It was possible to visually reconstruct the elemental maps on the surface of individual sands by XRF microprobe technique. In addition, the multielemental mass concentration could be quantitatively calculated for numerous spots of desert sands.

• Asian-Australasian Journal of Animal Sciences
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• 제21권11호
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• pp.1629-1634
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• 2008

A trial was conducted to determine the effect of low crude protein (CP) diets with constant metabolizable energy to crude protein (ME:CP) ratio on growth, body composition and nutrient utilization of broiler chicks from 1 to 26 days of age. Four dietary treatments having four levels of CP and ME as 23, 22, 21 and 20% and 3,036, 2,904, 2,772 and 2,640 kcal/kg, respectively, were formulated and a ME:CP ratio of 132 was maintained in all the diets. Digestible lysine was maintained at 1.10 of the diet. A total of 1,760 day-old Hubbard broiler chicks were randomly divided into 16 experimental units and each diet was offered to four experimental units at random. Feed intake was increased (p<0.05) while weight gain and feed conversion ratio were adversely affected (p<0.05) when the diets with low CP and ME were fed to broilers. Total protein intake and total ME intake were linearly decreased (p<0.05) and protein efficiency ratio and energy efficiency ratio were lower (p<0.05) than in the chicks fed dietary regimen with 22% CP and 2,904 kcal/kg ME. The whole body analysis of the birds revealed that chicks fed the lowest dietary regimens retained less (p<0.05) nitrogen and more ether extract than chicks fed the control diet, however, body dry matter, total body ash and fat free body protein were not affected. Similarly, protein and energy utilization were also unaffected by the dietary treatments. In summary, chicks fed low CP diets with constant ME:CP ratio grew slower, used feed less efficiently and retained less protein and more body fat than chicks fed the control diet.

• Journal of Korean Vacuum Science & Technology
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• 제6권2호
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• pp.79-83
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• 2002

As Ag does not form my silicide on Si surfaces, Ag wire is a candidate for self-assembled nanowire on the reconstructed and single-domain Si(5 5 12)-2 $\times$ 1. In the present study, various Ag coverages and post-annealing temperatures had been tested to fabricate a Ag nanowire with high aspect ratio. When Ag coverage was less than 0.03 ML and the post-annealing temperature was 500(C, Ag atoms preferentially adsorbed on the tetramer sites resulting in Ag wires with an inter-row spacing of ~5 nm. However, its aspect ratio is relatively small and its height is also not even. On the other hand, the Ag-posited surface completely loses its reconstruction even with the same annealing at 500 $\^{C}$ if the initial coverage exceeds 0.05 ML. But the additional subsequent annealing at 700$\^{C}$ and slow-cooling process recovers the well-ordered Ag chain with relatively high aspect ratio on the same tetramer sites. It can be understood that, in the double step annealing process, the lower temperature annealing is required for cohesion of adsorbed Ag atoms and the higher temperature annealing is for providing Ag atoms to the tetramer sites.

• Journal of the Korean Wood Science and Technology
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• 제32권4호
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• pp.1-7
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• 2004

소나무 간벌재로 톱밥보드를 만든 후 우드세라믹을 제조하여 수지함침율 및 소성온도에 따른 우드세라믹의 표면온도의 변화를 조사하였다. 실리콘러버 히터의 표면온도가 증가함에 따라 우드세라믹의 표면온도도 빠른 속도로 증가하였으며, 히터의 설정표면온도가 70℃ 일때 수지함침율 80% 시편의 표면온도는 53.9 ℃이었으며, 소성온도 1,000℃ 조건으로 제조된 우드세라믹의 표면 온도는 54.2 ℃로 가장 높았다. 히터의 표면온도보다 우드세라믹 표면온도의 하강 속도가 느려 우드세라믹이 오랜 시간 열을 유지하고 있음을 알 수 있었다.

• Structural Engineering and Mechanics
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• 제31권6호
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• pp.679-696
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• 2009

The paper aims at analyzing the stress distribution around an underground opening that is subjected to non-symmetrical surface loading with emphasis on opening shapes with sharp corners and the stress concentrations developed at these locations. The analysis is performed utilizing the BIE method coupled with the Neumann's series. In order to implement this approach, the special recurrent relations for half plane were proven and the modified Shanks transform was incorporated to accelerate the series convergence. To demonstrate the capability of the developed approach, a horseshoe shape opening with sharp corners was investigated and the location and magnitude of the maximum hoop stress was calculated. The dependence of the maximum hoop stress location on the parameters of the surface loading (degree of asymmetry, size of loaded area) and of the opening (the opening height) was studied. It was found that the absolute magnitude of the maximum hoop stress (for all possible surface loading locations) is developed at the roof points when the opening height/width ratio is relatively large or when the pressure loading area is relatively narrow (compared to the roof arch radius), and contrarily, when the opening height/width ratio is relatively small or when the surface pressure is applied to a relatively wide area, the absolute magnitude of the maximum hoop stress is developed at the bottom sharp corner points.

• 동아시아식생활학회지
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• 제15권6호
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• pp.655-662
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• 2005

Body content bone mined density and nutrient intake status of 129 college women in Daegu area are analyze4 The mean age was 23.1 years. Bone mineral density was measured in their right heel by SONOST-2000 ultrasound bone densitometer, and nutrient intake was assessed by a Questionnaire. Diet intake data were obtained by using a 24 hours recall method to evaluate the subject's usual diet. The average energy, Ca, Ee, Zn and folate intakes were 64.2, 47.5, 54.7, 62.9 and $57.4\%$ of RDA, respectively. Ca/P and Ca/Protein ratio were 0.46 and 6.7, respectively. The mean adequacy ratio(MAR), an index of overall dietary quality wag 0.6. The index of nutritional quality was under 1.0 for protein(0.7), vitamin A(0.9), E(0.7), $B_1(0.8)$, niacin(0.8), $B_6(0.6)$ and phosphorus(0.6). The less the protein and energy intake, the less the bone mineral density(p<0.05). The intakes of protein(p<0.05) and that of phosphorus(p<0.001) were positively correlated with bone quality index(BQI). The calcium intake was positively correlated with Z-score(p<0.05). The phosphorus intake was positively correlated with T-score(p<0.001) and Z-score(p<0.0001). In conclusion, this study indicates that nutrient intake of the college women is considerably lower than the RDA. Also the BQI is lower than standard.

• 여성건강간호학회지
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• 제25권4호
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• pp.434-445
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• 2019

Purpose: This study was conducted to examine the relationship between a mother's diagnosis of cervical cancer and attitudes toward cervical cancer prevention in their daughters. Their intention to recommend human papillomavirus (HPV) vaccination for their daughters, their confidence in 8 methods for cervical cancer prevention with their daughters, and their negative emotions about the assumption of their daughter's HPV infection. Methods: This study was a secondary analysis of data from the study of maternal health beliefs about preventing cervical cancer. The study sample were women who reported whether ever diagnosed with cervical cancer, who had pubertal daughters (n=1,578). Data were analyzed by cross-tabulation analysis, Spearman's rank correlation analysis, and logistic regression. Results: Mothers diagnosed with cervical cancer were more confident in using methods to prevent cervical cancer in their daughters (Z=-4.42, p<.001) and were more likely to feel negative emotions about the assumption of their daughters' HPV infection (Z=-2.44, p=.015) than mothers who were not diagnosed. Significant factors influencing their intention to recommend the HPV vaccination to their daughters were the mother's confidence in preventing cervical cancer in their daughters (odds ratio [OR], 1.003; 95% confidence interval [CI], 1.002-1.004) and their negative emotions about the assumption of their daughters' HPV infection (OR,1.016; 95% CI, 1.004-1.028). Conclusion: For the early prevention of cervical cancer in pubertal daughters, the education of their mothers should include interventions to increase confidence in preventing cervical cancer in their daughters and sensitivity of HPV infection toward daughters.