• Journal of Korean Society of Transportation
• /
• v.18 no.3
• /
• pp.29-39
• /
• 2000

Position of stop line according to left turn trajectory at intersections was studied. The Purpose of this study is to suggest a design guideline of left turn trajectory at intersections which is related to the Position of cross road stop line. Distance from the curb line to the stop line at each lane was calculated and discussed for various combination of road widths. Three design vehicle type and three control radii were considered. Setbacks of stop line from the curb line are Proportional to the control radius which depends on type of design vehicle. 8m, lim and 19m setback for control radius of 12m, 15m and 23m were calculated respectively as their maximum value. This result will be helpful to Paint the road marking on the Pavement which is usually difficult to fit to the designated radius. Field study of the effect of left turn trajectory on flow rate and safety was conducted. It was approved that improperly designed left turn trajectory decreases left turn capacity and increases conflicts among left turn flows of the adjacent lane.

• The korean journal of orthodontics
• /
• v.27 no.5 s.64
• /
• pp.733-741
• /
• 1997

As a result of surgical orthodontic treatment of mandibular prognathism, changes take place in the skeletal and soft orofacial components. Although some investigators had stated that permanent reduction of airway space was observed after mandibular setback surgery, it was not clear that this permanent reduction was sustained during long-term follow-up. The purpose of this study was to assess the changes in oropharyngeal airway space and soft tissue orofacial component following the mandibular setback surgery and during the follow-up period. The correlation between the changes of the oropharyngeal airway space and the changes of other soft tissue orofacial component was also assessed. The findings of this study were as follows ; 1. The oropharyngeal airway space area decreased following mandibular setback surgery for mandibular prognathism and continued to decrease during the follow-up period(p<0.05). 2. The pharyngeal depth at Xi point level and the 2nd cervical vertebra point level decreased after the surgery and remained during the follow-up period(p<0.05). The decrease of these pharyngeal depth was correlated with the decrease of oropharyngeal airway space area(p<0.01). 3. The decrease of pharyngeal depth at the 3rd and 4th cervical vertebra point level was not significant after the surgery and during the follow up period. 4. The hyoid bone moved downward after the surgery(p<0.05), but returned to its original position during the follow-up period. 5. The length & height of tongue and the Position of epiglottis base did not change significantly(p>0.05). 6. The soft palate was displaced posteriorly after the surgery and remained to its changed position during the follow-up period(p<0.05) due to posterior displacement of tongue. The changes of soft palate were significantly correlated with the decrease of oropharyngeal airway space area(p<0.01). 7. The narrowing of oropharyngeal airway space was due to the posterior displacement of tongue above the level of epiglottis tip. The posterior displacement of tongue following mandibular setback osteotomy remained during the follow-up period.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.20 no.3
• /
• pp.17-24
• /
• 2016

The reacting flows of gaseous hydrogen/liquid oxygen 2D coaxial shear injector with varying recess length are numerically analyzed. The standard ${\kappa}-e$ model and laminar flamelet model are adopted for the steady turbulent combustion with the ideal and real gas equations. As the recess length increases, the recirculating region in the combustion chamber expands and the vorticity is intensified. Also, the variations of temperature, products, and pressure are strongly related to the recess length. The results show that an efficient combustor can be obtained by the introduction of the recessed injector.

• The korean journal of orthodontics
• /
• v.32 no.3 s.92
• /
• pp.209-225
• /
• 2002

Enlow's counterpart analysis reflects the characteristics of each individual sample to find out the cause of the malocclusion and further applying them to the clinic. Enlow's counterpart analysis was performed on 100 Korean samples (50 male, 50 female) with normal occlusion and 100 skeletal class III patients (50 male, 50 female) scheduled for orthognathic surgery. The following conclusions were obtained. 1. The cause of malocclusion in skeletal class III patients were complex and interrelated : backward upward rotation of the cranial base, forward inclination of the ramus, increase in the mandibular body length, and posteriorly located maxilla. 2. Seen on R2 (male-1.68mm, female-2.33mm), in skeletal class III, the maxilla Is mote posteriorly located than the normal group. 3. The cause of malocclusion In skeletal class III patients, consists of retrognathic maxilla(A1) male $22\%$, female $26\%$, prognathic mandible(B1) male $44\%$, female $34\%$, and combination of an retrognathic maxilla and prognathic mandible were male $28\%$, female $38\%$. 4. There was no significant difference in the anterior-posterior length of the maxilla(A4) between skeletal class III males with the normal group, while in the female subjects, the skeletal class m group showed a smaller maxilla(A4) compared to the normal group. 5. In skeletal class III patients the proganthic mandible was primarily caused by the Inclination of the ramus(R3, R4) and mandibular body length(B4, B6) rather than ramus width(B3).

• Journal of Korean Institute of Industrial Engineers
• /
• v.28 no.2
• /
• pp.128-138
• /
• 2002

In this paper, we address how to reduce the length of tool retraction in a zigzag pocket machining. Tool retraction, in a zigzag pocket machining, is a non-cutting operation in which the tool moves to any remaining regions for machining. We developed an algorithm of generating tool retraction length in convex or concave polygonal shapes including islands. In the algorithm, we consider concave areas of cutting direction in the polygonal shape. Considering concave areas of cutting direction, the polygonal shape is decomposed to subregions which do not need any tool retraction. Using the proposed algorithm, we calculated the shortest length of tool retraction in cutting direction. Examples are shown to verify the validity of the algorithm.

• The Korea Swine Journal
• /
• v.23 no.9 s.265
• /
• pp.87-91
• /
• 2001

국내 돼지 인공수정은 1994년 이후 보급이 급속히 확산 되면서 1994년 보급률 $3\%$, AI센타수 5개소 이던 것이 현재는 보급률 50-60$\%$, AI센타수 60여개소로 최근 양돈관련 산업중 가장 성장한 산업중의 하나이며 중요한 양돈관련 업종의 하나로 자리 매김을 하였다. 그러나 그동안의 돼지 인공수정은 양적성장에 치중하여 왔고 최근에는 무분별한 납립으로 인한 과당경쟁과 불공평경쟁으로 인한 어려움으로 품질저하, 재투자 및 기술투자 의욕상실 등 국내 돼지인공수정은 뿌리를 든든히 내리기도 전에 성장이냐 쇄락이냐의 기로에서 위기상황을 맡고 있다. 따라서 이대로 방치 할 경우 기껏 양돈선진국 수준으로 올라선 인공수정산업이 보급률의 저하 등 산업 발전의 후퇴를 가져올 것으로 우려 된다. 이에 돼지 인공수정산업 각 부분별 문제점과 대안을 제시 하고자 한다.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.25 no.2
• /
• pp.151-163
• /
• 1992

Seasonal variations of water mass distributions in the Yellow Sea, the East China Sea, and the adjecent seas of Cehju Island, are investigated. A common seasonal variation over these whole areas is shown. Warm and saline waters are extended northwestward into the Yellow Sea in winter and retreated back southeastward to the East China Sea in summer. Barotropic numerical model results suggest that monsoon winds could drive such seasonal variations. Upwind flows play an important role in the processes. In the numerical model results, upwind flows are shifted to China. It is due to energy dissipations by complicated coast lines and shallow bottom topographies in the northern part of the Yellow Sea. The shifted routes of upwind flows agrees well with that of the southward extensions of the Yellow sea Bottom Cold Waters in summer.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.1
• /
• pp.1-9
• /
• 2014

The present study was conducted by using fast-responding PSP technique to measure the surface pressure on a small-scale rotor blade in hover. Also, the study was performed to verify the accuracy and investigate its possibility of PSP application for rotor blade pressure measurement. Pulsed laser which has 532 nm wavelength was used as a light source. Lifetime measurement technique was applied. Also, the coated paint on a rotor blade was porous PSP which has faster response time than conventional PSP. The blades had NACA0012 airfoils. The length of rotor blade was 340 mm and chord was 40 mm with rectangular shape 1 set, and 4 sets had several tip sweepback angles. The measured results qualitatively showed that the upper surface pressure decreases with increasing the collective pitch angle. Quantitative pressure coefficients of PSP results were higher approximately 0.4 to 0.7 than the pressure tap data of the NASA experiment.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.12
• /
• pp.1192-1200
• /
• 2009

This paper deals with an analytical study on the aileron reversal characteristics of anisotropic composite aircraft wings modelled as thin-walled beam and having bending-torsion structural couplings caused by Circumferentially Asymmetric Stiffness layup scheme. For a study on the aileron reversal of CAS composite wings, it is essential to consider the following effects such as warping restraint, transverse shear flexibility, bending-twist structural coupling, wing aspect ratio, ratio of span-wise and chord-wise length of aileron to wing, and sweep angle, etc. The results on the aileron reversal could have a significant role in more efficient designs of thin-walled composite wing aircraft for which this aeroelastic instability is one of the most critical ones.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.3
• /
• pp.264-270
• /
• 2008

Most of burning rate models used in hybrid combustion depend solely on oxidizer flux. But this empirical relation can not represent well the important effect of the thermo-chemical properties of solid fuel and thereby requires different value of empirical exponent and constant for each fuel considered. In this study, a new burning rate correlation was proposed using the mass transfer number(B number) which encompasses the thermochemistry effect of solid fuel and the aerodynamic effect caused by the combustion on the solid fuel surface where the effect of aerodynamic property in the mass transfer number was studied. The PMMA, PP, and PE were chosen as fuel, and gas oxygen as oxidizer. The new empirical burning rate expression depending on both the oxidizer flux and the mass transfer number was able to predict the burning rate of each fuel with just a single exponent value and constant, and it was found that the aerodynamic effect on the blowing effect did show a minor effect on the burning rate correlation.