• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2005년도 추계학술대회 논문집
• /
• pp.170-175
• /
• 2005

In this study, experimental and theoretical methods were applied to understand brake squeal noise VVVF rolling stock on tracks. Trailer cars needed to payed a particular attention, because they were the major source of brake noise. VVVF rolling stocks for lines no 1 of the subway system in Seoul were used for experimental analyses. In order to study brake squeal noise, a dynamometer test at the S&T Brake, Co., which was a manufacturer of brake pads had performed. For measuring vibration and noise, vibration tests of brake parts (brake lining, brake lining head, back plates, etc.) at the SNUT were executed. Also, vibration tests of disc assembly and lining block at the heavy maintenance shop of the Gunja depot were performed. The modal analyses by using an ANSYS which was one of the CAE commercial program were simulated to know the relationship to the mechanism of brake noise. On the based of the tests and the simulations it was found that specific frequencies of the brake parts affected squeal noise, and improvements for reducing squeal noise were proposed.

• 한국유기농업학회지
• /
• 제20권1호
• /
• pp.71-80
• /
• 2012

본 실험은 중부 지방에서 Rye(곡우)와 Triticale(신영)의 단, 혼파 실험을 통하여 생산성, 사료가치 및 가축사육능력을 조사하여 중부지방에 적합한 초종을 선별하고자 하였으며, 결과를 요약하면 다음과 같다. 동계 사료작물의 건물수량은 밭토양에서는 R+R이 5.20ton/ha로 가장 많았으나 R, T+R과 유의한 차이는 없었고, 논토양에서는 R+H가 5.20ton/ha로 가장 많았지만 T+H, R과의 유의한 차이는 없었다. 또한 모든 시험구에서 단파구에 대한 혼파구의 상대수량이 1.00보다 높아 혼파효과가 입증되었다. 상대사료가치는 밭토양, 논토양 모두 Triticale 혼파구에서 다른 시험구와 유의한 차이를 보였다. 가축사육능력은 $K_{CP}$와 $K_{TDN}$의 평균값으로 비교해 보았을 때, 밭토양에서는 R+R이 2.75, 논토양에서는 T+H가 2.84로서 가장 높은 값을 보였다. 이상의 결과로 볼 때 중부 지방에서 동계 사료작물 생산에 있어서 가장 적합한 초종은 밭토양에서는 Rye+Red clover 혼파이며, 논토양에서는 Triticale+Hairy vetch 혼파라고 판단된다.

• 디지털융복합연구
• /
• 제11권11호
• /
• pp.59-70
• /
• 2013

디지털 경제를 맞이하여 대부분 자산을 부동산에 투자하고 있어 향후 부동산 가격에 많은 관심을 보이고 있다. 다양한 변수들이 주택 등 부동산 시장에 영향을 미치고 있다. 그 중 대표적으로 세대주와 생산가능인구, 금리, 주가지수 등 4가지 변수들을 선정하여 어느 변수가 서울아파트 가격에 얼마나 통계적으로 유의하게 영향을 미치는지 살펴보았다. 본 연구는 실증적으로 서울아파트가격의 결정모형을 구축하는데 목적이 있다. 분석결과 주가지수만 서울아파트와 통계적으로 유의한 것으로 분석되었다. 세대주나 생산가능인구는 기존의 연구처럼 서울아파트와 방향성은 동일하지만 통계적으로 유의하지 않은 것으로 분석되었다. 독립변수 중에서 서울아파트 가격의 결정요인으로 주가지수만 주요 변수로 선정되었다. 본 연구결과 향후 주택 등 부동산시장의 예측하기 위해서는 주식시장의 전망이 선행되어야 할 것이다.

• 한국농촌생활과학회지
• /
• 제9권1호
• /
• pp.43-54
• /
• 1998

This study attempted to investigate the factors affecting financial status of the rural middle-aged and old-aged household. The results shelved that the significant variables which influenced on the probability of financial security measured by consumption to income ratio were sex and education level of the household head, family size, total income, total expenditure and total assets. The most influential variables on the probability of financial security measured by liquidity ratio was liquid assets, and total assets. Education level of the household head. liquid assets, total assets, and total debt had significant effects on the probability of financial security estimated by debt burden ratio. Among the economic variables, only liquid asset had significant negative effects on the probability of financial security assessed by the capital stock ratio.

• 대한기계학회논문집A
• /
• 제29권10호
• /
• pp.1416-1429
• /
• 2005

In order to meet the increasing competitive pressures coupled with higher demands for component quality, whirling machines have been at the cutting edge of the automobile industry for more than 25 years. The hard whirling process can save on machining time and operation elimination. Hard whirling is done dry, without coolant. The chips carry away nearly all of the heat during cutting, leaving the workpiece cool and minimizing any thermal geometry variations. The surface finish and profile accuracy are close to grinding quality. Whirling machines usually consist of four major parts; 1) loading system that requires the necessary axial speeds, 2) head stock that needs high precision clamping and positioning system at the chuck and tailstock, 3) whirling unit that demands the high cutting speeds and cutting power fer cutting deep thread profiles and 4) unloading system that requires an easy workpiece unloading. Also, capabilities of the whirling machine can be improved by attaching a vision system to the machine. Most of whirling machines in Korean automobile industry are imported from the Leistritz company, Germany and the Hasegawa company, Japan. Tn this paper, a basic research will be performed to improve and enhance the existing whirling machines. Finally, a new Korean whirling machine will be proposed and developed.

• 해양환경안전학회지
• /
• 제23권1호
• /
• pp.104-111
• /
• 2017

본 연구는 원심펌프 내부 유동장 특성에 대한 시뮬레이션 및 시각화에 중점을 둔다. 3D 수치해석은 Reynolds Average Navier-stock 코드를 k-${\varepsilon}$ 표준 2차방정식 난류 모델로 처리하여 수행하였다. 시뮬레이션은 흡입측, 임펠러, 토출측 영역에서 조도로 인한 마찰 손실과 임펠러 웨어링에서 체적 손실을 포함한다. 해석과 실험사이의 성능곡선 비교결과 최대 5 %의 작은 차이를 보이며 동일한 추세를 나타냈다. 최고 효율점에서 속도 벡터는 고르게 나타났지만 비 설계점에서는 현저한 변화가 나타났고, 텅 부근의 임펠러 유로토출부에서 강력한 재순환 영역이 나타났다. 비교적 일정한 압력분포가 텅 부근임에도 불구하고 임펠러 주위에 관찰되었다. 볼류트 내에서 기하학적으로 인해 형성된 나선형 와류가 이 영역에서 유동장이 상대적으로 난류이고 불안정하다는 것을 증명하였다.

• 한국임상수의학회지
• /
• 제16권2호
• /
• pp.428-438
• /
• 1999

A study was conducted to estimate cost of major dairy cattle diseases. Forty (n=40) of the 167 dairy herds in Gyeongnam (Chinju) area were stratified and selected randomly for participation in the national animal health monitoring system. Gyeongsnag University veterinarians, Gyeongnam Livestock Promotion Institute veterinarians and clinic veterinarian visited each herd once a month for a total periods of 12 months. At a each visit data on disease, production, management, finance, treatments, preventive activities, animal events, and any other relevant events were collected. Monthly and annual cost estimates of disease treatment were in computed in each herd and stratum(including cost of prevention). Results were expressed as cost per head and given separately for cows, young stock, and calves. In cows, the most expensive seven diseases entities (from the most to the least) were : (1) clinical mastitis; (2) breeding problems; (3)gastrointestinal problems; (4) multiple system problem; (5) birth problems; (6) metabolic/nutritional disease; (7) lameness. In young stock, the most costly disease were the multiple system problems, breeding problems, respiratory disease, gastrointestinal disease, and lameness. In calves, the most costly disease problems were gastrointestinal problems, respiratory disease, integumental, multiple system problems, and metabolic/nutritional problems.

• 한국식품조리과학회지
• /
• 제6권2호
• /
• pp.15-26
• /
• 1990

The material used for the experimental analyses and sensory evaluation of this thesis is 8 Bastards. 4 Bastards are used as Sample A and the other 4 Bastards are used as Sample B. Sample A is the broth from 100 grams of flesh and spinal bones, boiled for (1) 15 minutes, (2) 30 minutes, (3) 60 minutes, and (4) 120 minutes. Sample B is the broth from 100 gram of head and spinal bones, boiled for (1) 15 minutes, (2) 30 minutes, (3) 60 minutes, and (4) 120 minutes. The nutrients analyzed for this thesis are (1) free amino acid, (2) total N, and (3) minerals (Ca, P, Na, K, Zn). The results of the experimental analyses and sensory evaluation of Bastards broth with various boiling time are follows: (1) The total amounts of free amino-acid and total N in the broth are the greatest when boiled for 15 minutes, in both sample A and sample B. (2) The amounts of minerals in the broth increase as time increases. (3) The results of the sensory evaluation show that the subjects prefer the taste of the stock boiled for 120 minutes with regard to sample A, but that they prefer the taste of the stock boiled for 15 minutes with regard to sample B.

• 펄프종이기술
• /
• 제39권5호
• /
• pp.1-6
• /
• 2007

Formation which is one of the most fundamental characteristic of paper quality is affected by a number of variables. Fiber flocculation in the headbox has been recognized as the most important variable influencing formation. Consistency and crowding number of head box stock are known to represent the flocculation potential of stocks. The effects of consistency and crowding number on paper formation were studied by measuring the flocculation of fiber suspensions. Increasing consistency increased the degree of fiber flocculation. Especially the consistency of long fiber fraction was the most crucial factor of flocculation. Tensile strength of handsheets was furnish dependent rather than flocculation dependent. Crowding number of a furnish can be used for the characterization of stock flocculation.

• Fisheries and Aquatic Sciences
• /
• 제22권6호
• /
• pp.12.1-12.8
• /
• 2019

Background: Wild fish populations stock is continuously diminishing in the Indo-Ganges river basin, and the population status of most fishes is unidentified. The identification of the population status and the conservation of commercially important and endemic wild fish populations in this region are crucial for the management. The aim of this paper was to identify the population status of Cirrhinus reba, a promising aquaculture but vulnerable species in the Indo-Ganges river basin in Bangladesh. Methods: C. reba samples were collected from four isolated populations of the Brahmaputra (n = 30), the Padma (33), the Karatoya (31), and the Jamuna Rivers (30) in Bangladesh, and the population status was evaluated using morphometric and landmark comparisons. Data were analyzed with the Kruskal-Wallis test, univariate analysis, discriminant function analysis, and the formation of a dendrogram. Results: Three meristic characters (Pectoral fin rays, caudal fin rays, scale in lateral lines), four morphometric characters (head length, pre-orbital length, post-orbital length, maximum body depth), and truss measurement (4-7) were significantly different among the stocks. The step-wise discriminant function analysis retained 15 variables from morphometric and landmark measurements that significantly differentiated the populations based on the constructed DFI and DFII. Discriminate function analysis also showed that 91.2% of the original groups were classified into their correct samples. The cluster analysis of Euclidean distances placed the Jamuna population in one cluster and the Brahmaputra, the Padma, and the Karatoya populations in the second one. Conclusion : Morphological differences among the stock were probably due to different ancestral origin. This is the first report about population status of C. reba in their natural habitat of the Indian subcontinent. Further genetic studies and the evaluation of environmental impact on C. reba populations in Bangladesh are suggested to support our findings.