• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2000.11a
• /
• pp.243-250
• /
• 2000

배관을 지하에 매설할 경우 매설배관이 묻히는 깊은 도랑을 트랜치라 하는데 이 트랜치의 폭과 깊이의 칫수를 적절하게 결정하는 것은 매설배관의 건전성을 유지하는데 중요한 인자중의 하나이다. Watkins는 매설배관의 트랜치 폭에 대한 연구를 수행하여 최근 그 결과를 발표한바 있다. (1) Fig. 1에 트랜치와 배관의 단면도를 그리고 일반적으로 사용하는 기술적인 용어를 나타내었다.(중략)

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1992.10a
• /
• pp.86-90
• /
• 1992

스크류 압축기는 진동이 작고 맥동이 적으며, 소형이고 고효율이라는 특징이 있다. 또한 식품, 화학, 전자공업 등에서 무윤활식 압축기로 사용되어지고 있다. 본 연구에서는 호프로 자른 것과 같은 다각형 오차를 만들지 않고 매끄러운 면을 얻을 수 있는 스크류 로터의 축직각 단면좌표를 이용한 cutter의 형상을 설계하는 것을 목적으로 한다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2002.05a
• /
• pp.151-151
• /
• 2002

• 한국HCI학회:학술대회논문집
• /
• 2006.02a
• /
• pp.161-168
• /
• 2006

본 연구는 공간적 정보의 청각적 제시 가능성을 확인하기 위해 머리전달함수(head-related transfer function: HRTF)를 통해 생성된 3D 사운드를 가상공간상 대상 위치의 직각형태(orthogonal pattern), 혹은 대각형태(diagonal pattern)의 조합으로 배열하여 투시장치(See-Through HMD)로 증강현실을 경험하고 있는 사용자 과제수행의 정확성을 측정하였다. 본 연구에서 실시한 실험들의 결과를 종합하면, 3D 사운드로 대상의 위치 정보를 제시할 때는 사용자로부터의 방향은 직각으로 위치시키는 정보 배열이 정확성을 확보할 수 있고, 또한 가상적 깊이를 이용하여 정보를 배열하는 것도 그 깊이를 구분할 수 있으나 정확성이 떨어짐을 확인하였다. 특히 보다 현실적인 과제 상황에서의 수행을 비교하기 위해 일차과제(primary task)를 하는 동안 제시된 청각자극 조건에서 이런 정확성의 차이가 마찬가지로 나타났다. 이런 결과를 통해 3D 사운드로 대상의 위치와 같은 공간적 정보를 제시 가능한 최적의 배열 형태를 제안하는데, 이는 어떤 패턴으로 정보를 구조화하여 제시하느냐에 따라 청각적 위치 정보 제시의 성공 여부가 결정된다는 것을 의미한다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.7
• /
• pp.145-151
• /
• 2019

The fragility analyses for the partially filled horizontal cylindrical tank having a flexible wall were conducted to evaluate seismic performance. An equivalent simplified model with two lumped masses representing to impulsive and convective masses was used to represent the liquid storage system. This simplified model was validated by comparing its time history analysis results with the 3D FSI model results. The horizontal tank was analyzed under bi-directional excitations. Seismic fragility curves for the stability were developed in transverse and longitudinal directions. Fragility curves show that seismic damage for the horizontal storage system is more susceptible in the transverse direction.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.1
• /
• pp.67-72
• /
• 2011

The main objective of this paper is obtaining the optimal carburizing hours which impacts geometric tolerances, OPD(Over Pin Diameter), runout, hardness and fatigure strength of SCM415 spur gear. In order to observe the deformation of the gear, the circularity, squareness, OPD(Over Pin Diameter) and runout were measured at 3hour, 4hour and 5hour respectively. As the result, the 3hour situation is the best, which very similar with the 4hour one. Afterwards, with the purpose of getting the result of gear hardness, the surface hardness, maximum hardness and interior hardness were measured. The result is 5h situation is the best, and it's similar with 4hour one. At last, the fatigue tests have been done which receive the result that the 4h situation showed 9~12% fatigue strength improvement compared with the 3h and 5h ones. To sum up the results, the 4hour situation shows the best performance in accuracy, hardness and fatigue strength.

• Tribology and Lubricants
• /
• v.15 no.3
• /
• pp.257-264
• /
• 1999

Recently as electronics and semi-conductor industry develop, ultra-precision machine tools that use air-spindle with externally pressurized air bearing appear in need of ultra-precision products which demand high precision property. Effects of air compressibility absorbs the vibration of shaft, this is called averaging effect, however, the higher running accuracy is demanded by degrees, the more important factor is machining errors that affect running accuracy of shaft. Actually, it would be very important in the view points of running accuracy to understand effects of machining errors on the running accuracy of the spindle system quantitatively to design and manufacture precision spindle system in the aspect that efficiency in manufacturing spindle system and performance in operation. So fu, there are some researches on the effects that machining error affect running accuracy. However, because these researches deal with one bearing of spindle system, these results aren't enough to explain how much machining errors affect running accuracy in the typical spindle system overall. In this study, we investigate the effects of the perpendicularity error of bearing and shaft on running accuracy of spindle system that consists of journal and thrust bearing theoretically, and suggest design guideline about shape tolerances.

• School Mathematics
• /
• v.15 no.1
• /
• pp.1-14
• /
• 2013

The purpose of this study is to examine the way of teaching the concept of pyramid in the elementary mathematics textbook and try to improve the problem. Although textbook present the general definition of pyramid as including regular pyramid, right pyramid, oblique pyramid, the textbook intentionally deal with right pyramid or regular pyramid. This intention reflect the intuition or familiarity of students. But, according to the analysis, this intention do not realized. The example of pyramid presented in the textbook do not coincide with mathematical definition and intuition of students. If we intend to deal with right pyramid in the textbook, we should treat of regular pyramid and right pyramid whose base is a rectangular in the textbook.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.7 no.2
• /
• pp.133-141
• /
• 2005

The behavior of the ground in crossed zone due to the excavation of new lower tunnel rectangularly crossed to that was studied by model tests and numerical analysis in shallow cover. Results of the model tests show that earth pressure of the ground in crossed zone were redistributed due to the longitudinal arching effect by the excavation of lower tunnel. By the numerical analysis, minimum principal stress in crown of single tunnel has more decrease than parallel tunnel or crossed tunnel. Vertical stress at rectangularly crossed tunnel decrease more than single tunnel by stress shadow.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.1
• /
• pp.74-79
• /
• 2011

Alignment systems with multi-axis motions are applied to determine vertical arrangement of multilayer assembly such as LCD, PDP, and MLCC. This study reports the development of XY${\theta}$ alignment stage which is designed as thin-type structure and parallel actuations. The thin-type parallel XY${\theta}$ alignment stage is maintained below $1{\mu}m$ in repeatability error. The squareness and straightness also allow precise motion for the alignment by the developed stage. The measured error is ${\pm}6.25{\mu}m$ in the alignment experiment by the vision system on the parallel XY${\theta}$ alignment stage.