• Transactions of the Korean Society of Mechanical Engineers
• /
• 제16권7호
• /
• pp.1381-1390
• /
• 1992

This paper presents a dynamic characteristics of flow induced vibration of circular cylinder set with inclined angle against flow direction. The effect of the cylinder bounded by spiral fin and wire on the damping of flow induced vibration is investigated, i.e., inclined angle, spiral pitch angle and number of spiral thread are studied. As the results, the cylinder with spiral fin is most effective for the damping. Also the cylinder bounded by pitch angle 50.deg. and 2 spiral thread is most effective.

• Journal of Astronomy and Space Sciences
• /
• 제12권1호
• /
• pp.112-122
• /
• 1995

We assume that the KOREASAT fails the entry of the geostationary orbit due to the error at the apogee kick motor firing. A simulation is done for the satellite that has a geosynochronous orbit with a non-zero degree inclination angle due to the failure at the apogee kick motor firing caused by the unbalance of the fuel storage and the spin of the thrust vector, etc. We analyzed the evolution of the orbit using the perturbation theory and calculated the changes of the eccentricity and the inclination. WHen a communication satellite has the figure eight trajectory, the beam point also traces the satellite. In this paper, We develope an algorithm to attack the above problem by stabilizing the beam point using the adjustment of the roll angle of the satellite. The spin action on the polarization plane that occurs when a satellite passes the ascending node and descending node affects the efficiency of the communication a lot, so we did another simulation for the better yaw angle adjustment for the KOREASAT to reduce the spin actino on the polarization plane.

• Journal of the Korean Geotechnical Society
• /
• 제19권6호
• /
• pp.285-298
• /
• 2003

Shear properies of geosynthetic/geosynthetic and geosynthetic/soil interfaces which are widely met in landfill sites were evaluated from the inclined board tests. The inclined board testing apparatus is known to reproduce the shear behavior on the low normal stress most accurately. In this study, the friction angle of each interface was estimated and the tensile force mobilized at the geosynthetic was measured as well. The test results showed that the friction angle of each interface and the tensile force of the geosynthetics depended on the amount of normal stress, the type of the geosynthetics used, and the combinations of geosynthetics and soils. In addition, the sand/geotextile/geomembrane interface system was simulated in this study, and it was observed that the tensile force developed at the geomembrane decreased due to the protection effect of the geotextile located above the geomembrane. The test results of this research was compared with those of direct shear tests published, too. Finally, by comparing the measured tensile force of the geosynthetics when the initial displacement of the box occurs, when the slope is called as the critical slope, with suggested analytic solution, the accuracy of analytic solution and the applicability to design were identified.

• The Journal of Korean Academy of Prosthodontics
• /
• 제49권1호
• /
• pp.22-28
• /
• 2011

Purpose: This article attempted to examine how teeth for restoration is made in a clinical practice and utilize it as future educational material of teeth formation and basic data for additional research. Materials and methods: This experiment investigated the models sent to milling center for production of zirconia crowns. After scanned with Lava CAD/CAM System (3M ESPE, Seefeld, Germany), they are measured on 'ImageJ (version 1.32j, National Institutes of Health, USA)' program and compared and analyzed. Convergence angle from mesio-distal surfaces and bucco-lingual surfaces of each teeth are measured. Also, bucco-lingual diameter of the region lowered as much as 0.4 mm from incisal edge in anterior teeth except canines.(This measure is defined as the Peak 0.4) The analysis of data between each group was conducted by Windows SPSS statistic program, and was proved significant on 95% confidence level by independent t-test, one-way ANOVA and multiple analysis (Sheff${\'{e}}$ test). Results: The mean value of convergence angle was $18.67^{\circ}$ It is ranked as molar ($26.70^{\circ}$) > premolar ($16.87^{\circ}$) > anterior teeth ($14.81^{\circ}$) in the order of mesio-distal convergence angle; anterior teeth ($22.32^{\circ}$) > molar ($20.93^{\circ}$) > premolar ($15.41^{\circ}$) in the order of bucco-lingual convergence angle. The mean value of Peak 0.4 was 1.18 mm. Conclusion: Convergence angle of abutment of zirconia all ceramic crown has difference depending on the location in the arch. Due to the nature of production of zirconia all ceramic crown, convergence angle of abutment and line angle finishing degree can have an effect on internal suitability of restoration.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
• /
• 한국GIS학회 2010년도 춘계학술대회
• /
• pp.128-129
• /
• 2010

기존의 고도계는 레이더 특성에 의해 직하부의 높이 값을 정밀하게 관측할 수 없었다. 그러나 레이더 간섭 고도계는 SAR(Synthetic Aperture Radar) 영상의 칩 펄스(Chirp Pulse)를 이용한 고정밀 경사거리(Slant Range Distance)관측, 도플러 효과를 이용한 고정밀 경사각(Squint Angle)의 관측 및 레이더 간섭기법(SAR Interferometry)을 이용한 고정밀 관측각(Look Angle)의 관측을 가능하게 하였다. 이 연구의 목적은 레이더 간섭 고도계의 효율적인 신호처리 기법의 개발에 있다.

• Transactions of the Korean Society of Mechanical Engineers
• /
• 제15권3호
• /
• pp.1001-1010
• /
• 1991

본 연구에서는 천이유동의 존재를 밝히고 천이영역과 경사각의 관계, 유동 및 열전달특성을 구명하고자 한다.이를 위해 유한차분방법(FDM)으로 수치해석하고 실 험결과와 비교, 검토하였다.

• The korean journal of orthodontics
• /
• 제28권5호
• /
• pp.791-802
• /
• 1998

The purpose of this study was to obtain the angulation and inclination of FACC of all teeth to FH plane. Study models of 31 persons with normal occlusion were selected and mounted on the semiadjustable articulator for this study. Using T.A.R.G. with a little modified method, the angulation and inclination of FACC of all teeth to FH plane were measured and then the measurements were analyzed statistically. The obtained results were as follows. Mean, standard deviation, maximum value, and minimum value of the angulation and inclination of FACC of upper and lower teeth were obtained. $\cdot$The FACC in both upper and lower arch was progressively lingually-inclined from anterior teeth to posterior teeth. $\cdot$In the angulations of FACC of upper teeth, central and lateral incisor showed similar value. Yet, the FACC of the rest was progressively distally-angulated from the canine to posterior teeth. The FACC in lower arch was progressively mesially-angulated from anterior teeth to posterior teeth. $\cdot$The angulation and inclination of FACC of any tooth in both upper and lower teeth correlated strongly and positively with the angulation and inclination of FACC of adjacent tooth.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 한국화재소방학회 2013년도 추계학술대회 초록집
• /
• pp.212-213
• /
• 2013

등록 장애인의 수가 매년 증가함에 따라 휠체어 사용 장애인도 역시 증가하고 있으며, 이들은 일상생활에서 휠체어가 필수적이며 건축물 공간 내에서 수직이동을 위해 경사로도 필요하다. 휠체어 사용 장애인의 접근성 확보를 위한 수직이동시설 중 하나인 경사로의 경우 1/12라는 기울기로 인해 많은 공간을 차지하게 되므로 건축물 내 경사로 설치에 소극적으로 대처하고 있다. 기울기(1:12, 1:10, 1:8, 1:6)를 조절할 수 있는 경사로를 설치하여 20대, 30대, 40대, 50대, 60대 각 연령별로 남녀의 비율을 같게 하여 수동식 휠체어를 사용하여 이동 실험을 하였다. 화재와 같은 긴급피난 시 경사로 설치를 통해 계단으로 이동하지 못 하는 휠체어 사용 장애인들의 자력피난과 화재안전을 확보하고자 연구를 진행하였다.

• The Journal of Engineering Geology
• /
• 제19권1호
• /
• pp.99-108
• /
• 2009

Since the preexisting evaluation methods of landslide susceptibility take somehow long time to determine the slope stability based on the field survey and laboratory analysis, there are several problems to acquire immediate evaluation results in the field. In order to overcome the previously mentioned problems and incorrect evaluation results induced by some subjective evaluation criteria and methods, this study tried to develop a method of landslide susceptibility by a quantitative and objective evaluation approach based on the field survey. Therefore, this study developed an evaluation chart for landslide susceptibility on natural terrain using the AHP analysis method to predict landslide hazards on the field sites. The AHP analysis was performed by a questionnaire to several specialists who understands mechanism and influential factors of landslide. Based on the questionnaire, weighting values of criteria and alternatives to influence landslide triggering were determined by the AHP analysis. According to the scoring results of the analysed weighting values, slope angle is the most significant factor. Permeability, water contents, porosity, lithology, and elevation have the significance to the landslide susceptibility in a descending order. Based on the assigned scores of each criterion and alternatives of the criteria, an evaluation chart for landslide susceptibility was suggested. The evaluation chart makes it possible for a geologist to evaluate landslide susceptibility with a total score summed up each alternative score.

• Journal of Korean Tunnelling and Underground Space Association
• /
• 제10권3호
• /
• pp.245-256
• /
• 2008

The steel rib, one of the main support of tunnel, plays a very important role to stabilize tunnel excavation surface until shotcrete or rockbolt starts to perform a supporting function. In general, a steel rib at the horizontal funnel is being installed in the direction of gravity which is known favorable in terms of constructability and stability. However, as the direction of principal stress at the inclined tunnel wall is different from that of gravity, the optimum direction of steel rib could be different from that at the horizontal tunnel. In this study, a numerical method was used to analyze the direction of force that would develope displacement at the inclined tunnel surface, and that direction could be the optimum direction of steel rib. The support efficiency of steel rib could be maximized when the steel rib was installed to resist the displacement of the tunnel. Three directions which were recommended for the inclined tunnels in the Korea Tunnel Design Standard were used for the numerical models of steel rib direction. In conclusion, the results show that all displacement angle of the models are almost perpendicular to the tunnel surface regardless of face angle. So if the steel rib would be installed perpendicular to the inclined tunnel surface, the support efficiency of steel rib could be maximized.