• 한국정밀공학회지
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• 제25권5호
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• pp.69-76
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• 2008

Inner diameter of bearing race is automatically measured by complete inspection system after grinding process. Contact type three points supporting method is widely applied to automatic inner diameter measurement because of its excellent stability. However, the geometric consideration regarding three points supporting method is not sufficient. In this study, the error equation from geometric error analysis of three points supporting method is found. The effect of factors in the error equation is also investigated. The error equation is linear for difference of diameter in sample and master on range of tolerance. An error becomes more and more larger, when the distance of two supporting balls or the diameter of supporting ball are increased. In the result, some considerations are proposed for measurement of inner diameter by the three points supporting method.

• 전자통신동향분석
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• 제16권1호통권67호
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• pp.24-35
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• 2001

AAA는 복잡한 Inter-domain 응용 서비스의 등장으로 인해 이들 서비스들을 신뢰성 있고 안전하게 관리하기 위해 사용된다. IETF에서는 AAA를 위해 Remote Authentication Dial-In User Service(RADIUS)와 DIAMETER 프로토콜을 제안하고 있다. DIAMETER는 기존의 PPP와 Roaming, Mobile IP 같은 새로 출현하는 정책과 AAA 서비스를 위한 확장 기능을 제공하기 위한 Peer 기반의 가벼운 AAA 프로토콜이다. 본 논문에서는 DIAMETER 프로토콜에 대한 개요 및 메시지, 형식, 그리고 라우팅 방식에 대해서 기술한다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제8권3호
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• pp.13-22
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• 2003

현장공기분사공정의 복원효율에 있어서 중요한 인자로 작용 할 수 있는 것은 공기가 지하 포화대수층을 통과하면서 생기는 공기분사에 따른 흐름 양상과 토양입자크기에 따른 공기의 영향반경이다. 토양입자크기별 AMG 0.34, 1.38, 3.89 mm diameter 3가지 입자크기로 실험한 결과 AMG 0.34 mm diameter의 포화 대수층에서는 공기가 처음 결정된 방향으로만 흐르는 채널링 현상(channelized air flow)과 포화 대수층 가장 윗면에서는 확장모양(expansion state)을 가졌으며, 공기영향반경은 단위 면적당 15.2%/$\textrm{m}^2$이었다. AMG 1.38, 3.89 mm diameter의 포화 대수층에서는 공기가 퍼지는 현상(pervasive air flow)과 포화 대수층 가장 윗면에서는 각각 붕괴의 조짐(onset of collapse), 안정한 상태로 퍼짐모양(approach to steady state)을 가졌으며, 단위면적당 각각 37.0%/$\textrm{m}^2$, 30.0%/$\textrm{m}^2$영향반경이 계산되었다. 이 실험을 통해서 현장공기분사공정에 있어서 토양입자 크기에 따른 최대 영향반경효율을 얻을 수 있는 토양입자의 크기는 AMG 1.5-2.5 mm diameter로 사료된다.

• 한국정보과학회논문지:시스템및이론
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• 제34권5_6호
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• pp.176-186
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• 2007

상호연결망은 그래프로 모델링 할 수 있다: 노드는 정점으로 대응시키고, 링크는 에지로 대응시킨다. 상호연결망(그래프)의 지름은 서로 다른 모든 두 정점 사이의 최단경로 길이 중 최대이다. 상호연결망의 고장지름이란 연결도-1 개 이하의 임의의 정점에 고장이 있을 경우, 이들 고장 정점들을 제거한 연결망에서 모든 두 정점사이의 최단경로 길이 중 최대이다. 지름이 3이상이고 연결도가 r인 r-정규(regular) 그래프의 고장지름은 지름+1이상이다. 이 논문에서는 $m,n{\geq}3$ 인 2-차원 $m{\times}n$ 토러스에서 m=3 혹은 n=3일 때 고장지름은 max(m,n)이고, m,n>3일 때 고장지름은 지름 +1임을 보인다. 그리고 $k_i{\geq}3(1{\leq}i{\leq}d)$이고 $d{\geq}3$인 d- 차원 $k_1{\times}k_2{\times}{\cdots}{\times}k_d$ 토러스에서 서로 다른 임의의 두 정점 사이에 길이가 지름+1이하인 서로소인 경로들이 2d 개 존재함을 보인다. 두 정점 u와 v 사이의 서로소인 경로들이란, 공통의 정점들이 u와 v만 있는 경로들을 말한다. 이들 서로소인 경로들을 이용하여 $k_i{\geq}3(1{\leq}i{\leq}d)$이고 $d{\geq}3$인 d-차원 $k_1{\times}k_2{\times}{\cdots}{\times}k_d$ 토러스의 고장지름이 지름+1임을 보인다.

• 대한기계학회논문집B
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• 제25권1호
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• pp.54-61
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• 2001

Condensing heat transfer coefficients of R-22 and R-134a were measured in smooth, horizontal copper tubes with inner diameters of 1.77mm, 3.36mm, and 5.35mm, respectively. The experiments were conducted in the closed loop, which was driven by a magnetic gear pump. Data are presented for the following range of variables : mass velocity from 200 to 500kg/$m^2$.s and quality from 0 to 1.0. The heat transfer coefficients in the small diameter tubes (ID < 7mm) were observed to be strongly affected by various diameters and the heat transfer characteristics in the small diameter tubes differed from those in the large diameter tubes. Heat transfer coefficients in the small diameter tubes are higher than those in the large diameter tubes at the same experimental condition. It was found that some well-known previous correlations(Shahs correlation and Cavallini-Zecchins correlation) were not suitable for small diameter tubes.

• 한국생산제조학회지
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• 제24권2호
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• pp.160-165
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• 2015

The 14k, 45k, and 70k Mw PCL have different crystallization temperatures and therefore have slightly different characteristics affecting the fiber diameter. To observe these behaviors, the fiber was produced at every step of $10^{\circ}C$ for each molecular weights and the diameter was measured. Moreover, the fiber was fabricated over the cooled ground plate to observe the change in fiber diameter in comparison to the normal ground plate. In case of molecular Mw 14k PCL, the diameter increased as the temperature increased. For Mw 45k PCL, the fiber diameter decreased as the temperature increased. As of Mw 70k PCL, the fiber diameter decreased with increasing temperature as well. When the experiment was conducted over the cooled collector plate, the data did not change significantly from the previous lexperiments.

• 대한기계학회논문집B
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• 제27권7호
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• pp.920-928
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• 2003

The objective of the present study was to investigate the characteristics of flow and wall shear stress under steady and pulsatile flow in the aneurysm. The numerical simulation using the software were carried out for the diameter ratios ranging from 1.5 to 3.0, Reynolds number ranging from 900 to 1800 and Womersley number, 15.47. For steady flow, it was shown that a recirculating vortex occupied the entire bulge with its core located closer to the distal end of the bulge and the strength of vortex increased with increase of the Reynolds number and diameter ratio. The position of a maximum wall shear stress was the distal end of the aneurysm regardless of the Reynolds number and diameter ratios. For the pulsatile flow, a recirculating flow at the bulge was developed and disappeared for one period and the strength of vortex increased with the diameter ratio. The maximum values of the wall shear stress increased in proportion to the diameter ratio. However, the position of a maximum wall shear stress was the distal end of the aneurysm regardless of the diameter ratios.

• Journal of Advanced Marine Engineering and Technology
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• 제33권6호
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• pp.827-834
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• 2009

The cooling heat transfer coefficient of $CO_2$ in a brazing type small diameter tube was investigated experimentally. The main components of the refrigerant loop are a receiver, a $CO_2$ compressor, a mass flow meter, an evaporator and a brazing type small diameter tube as a test section. The mass flux of $CO_2$ is $400{\sim}1600$ [kg/$m^2s$], the mass flowrate of coolant were varied from 0.15 to 0.3 [kg/s], and the cooling pressure of gas cooler were from 8 to 10 [MPa]. The cooling heat transfer coefficients of the brazing type small diameter copper tube is about $4{\sim}11.7%$ higher than that of the conventional type small diameter copper tube. In comparison with test results and existing correlations, correlations failed to predict the cooling heat transfer coefficient of $CO_2$ in a brazing type small diameter copper tube. therefore, it is necessary to develope reliable and accurate predictions determining the cooling heat transfer coefficient of $CO_2$ in a brazing type small diameter copper tube.

• 한국약용작물학회지
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• 제17권6호
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• pp.452-457
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• 2009

This study was carried out to investigate the correlation between root diameter and ginsenoside composition of Panax ginseng C. A. Meyer cultivar Yunpoong. Dry matter ratio of main root was a little higher than that of lateral root and fine root, and that was higher by the increase of root diameter in the same root parts. Total ginsenosides composition of main and lateral roots increased by the decrease of root diameter, especially in lateral root. Similar resulted in fine root, but there was no significant difference where root diameter was below 2.5 mm. Except for ginsenoside-$Rg_1$, other ginsenosides component, PDs, PTs and total ginsenosides had highly negative correlation with the root diameter within whole root, main root+lateral root and lateral root+fine root, while $Rg_1$ had positive correlation with the root diameter.

• 터널과지하공간
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• 제21권5호
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• pp.386-393
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• 2011

본 연구에서는 암반 내 원통형 공동면에 나타나는 절리선 길이분포를 이용하여 암반 내에 존재하는 절리의 직경분포를 추정하기 위한 알고리듬을 제안하였다. 암반 내 절리의 직경분포를 추정하기 위해서 송재준(2005)에 의해 제시된 Joint Center Volume(JCV)의 개념이 적용되었다. 평면 조사창에 나타나는 절리선에 대한 JCV 값을 산정하는 송재준(2005)의 알고리듬을 확장하여, 원통형 공동면을 조사창으로 하는 경우의 암반 내 절리 직경분포 추정을 위해 전수조사 기법을 적용한 JCV 계산 알고리듬을 개발하였다. 추정된 절리 직경분포는 Monte-Carlo 시뮬레이션 기법을 이용하여 절리직경 모분포와 비교 검증하였으며 추정된 절리 직경분포가 모분포와 20% 내외의 오차 범위에서 수렴하는 것을 확인하였다.