• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.5
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• pp.341-347
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• 2002

This study was designed to determine the location of the mandibular canal on lower molar areas. Thirty-three patients were examined with multi-planar reformatted CT scan($Dentascan^{(R)}$). Three kinds of measurements were performed. The first was the distances between the upper border of the mandibular canal and the root apices of the first and second molars, the second was the distance between the cortical plate of the mandible and mandibular canal, and the last was the location of the mandibular canal in the buccolingual plane. The obtained results are as follows 1. The distance between the root apices of lower molars and the superior border of mandibular canal was largest at the mesial root of the first molar, and shortest at the distal root of the second molar(p<0.05). 2. The longest distance between the outer surface of the buccal cortical plate of the mandible and mandibular canal was measured from the distal root of the second molar, and this distance decrease gradually mesially(p<0.05). 3. The distance between the mandibular base and inferior border of mandibular canal was longest at the distal root of the second molar, and shortest at the mesial root of the first molar(p<0.05). 4. The location of mandibular canal was lingually positioned in relation to the axis of teeth and alveolar ridge in molar areas.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.1
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• pp.34-46
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• 2020

Computational assessment of gas-dynamic characteristics is explored for a three-dimensional counter-flow thrust vector control system in a rectangular supersonic nozzle. This convergent-divergent nozzle is designed by Method of Characteristics and its design Mach number is specially set as 2.5. Performance variations of the counter-flow vector system are illustrated by varying the gap height of the secondary flow duct. Key parameters are quantitatively analyzed, such as static pressure distribution along the centerline of the upper suction collar, deflection angle, secondary mass flow ratio, and resultant thrust coefficient. Additionally, the streamline on the symmetry plane, three-dimensional iso-Mach number surface contour, and three-dimensional turbulent kinetic energy contour are presented to reveal overall flow-field characteristics in detail.

• Plant Journal
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• v.15 no.3
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• pp.35-41
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• 2019

In this study, we investigated the effect of the generation of NOx and CO by adjusting the overfire air supply position and ratio using the boiler that was converted from coal burning to wood pellet boiler. When the amount of the overfire air is relatively increased, the amount of NOx is slightly decreased but CO is sharply decreased when burning at low excess air ratio (1.10) that is due to a small fuel particle size. However, NOx slightly increased when burning at high excess air ratio (1.33) due to the large fuel size, but CO was hardly affected. Also, When the amount of overfire air was same, The more supply position was concentrated to upper portion of the main combustor, the more NOx and CO was lowered. And in case of the excess air ratio was high, the generation of NOx and CO I can see that it keeps the level irrelevant to the amount of air for the second stage combustion.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.249-252
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• 2008

The solutions are expressed in terms of a double integral transformation over wavenumber and frequency. The complete solution is considered in such a full wave theory approach. This method can handle a larger number of plane layers. Therefore, the result of FK method is very similar to real data. Using the models that were modified in velocity and Q value with depth by iterative process from a model (Kang and Park, 2006) and considered as one of the best models in Korean Peninsula, the synthetic data are simulated for explosions and earthquakes of North Korea. This study notes that the wave shape of the synthetic data is very dependent on Q value, velocities, and thickness of sedimentary layers. Comparing between the real and the synthetic, fitting well in arrival time of first arrival and wave shape causes us to arrive at an indication that the model is very close representation of upper crustal structure and simulations are well done in amplitude fitting and in identification of phases of local and regional waves.

• Journal of Korean Society of Rural Planning
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• v.4 no.2
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• pp.8-19
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• 1998

The problem of outdated and surplus facility-items in existing Rural Living Environment Renewal Program(RLERP) makes this study focus on restricting the range of facility sorts for the purpose of coㅁins with the changing rural living environment. In the four aspects of plan establishment, project implementation, comprehensiveness and linkage between programs, this study made an analysis of the existing RLERP that has 4-stage hierarchy, namely, Gun(county), Myun(primary administrative district), village and project site level Firstly, Myun and upper level policy programs fulfill the comprehensiveness and planning aspects, but have defects in the implementation and linkage aspects. Secondly, the village level programs satisfies more or less the four condition, but give rise to the problems of equity between the project target village and the non-target, and of generalization of the planning method applying to a specific village. At last, project level programs, controlled by several ministries, have defects in comprehensiveness and linkage aspects, exposing the sectoralism of central government. Above all, the existing RLERP has so many facility items, which have led to inefficient investment till now. Therefore, it's necessary that the environmental facilities should be selected(simultaneously reduced ), referring to following 5 criteria. (1) Exception of facilities relating to agricultural production. (2) Confined to public facilities to be constructed by government support. (3) Common-use facilities located in small town and below level area. (4) Consideration of not only the present need but also the future need of rural residents. (5) Reflection of a regional difference of mountain, plane and suburban area. Just 13 kinds of living environmental facilities are finally selected as the result of the selecting work, which can be an new alternative for RLERP. Concludingly, the selected facility items should be integrated into a designated project site by the prepared plan in order to enhance the efficiency of RLERP, investment and also to satisfy the four analytic aspects mentioned above.

• Journal of Korean Society of Rural Planning
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• v.11 no.1 s.26
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• pp.1-8
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• 2005

The purpose of this study is to develop a simulation model of rural road path for infrastructure of green-tourism and public service in rural areas. This study makes an objective function for moving cost minimization considering car travel time according to road characteristics, which can route the optimal shortest road paths between the center places and all rear villages, based on GIS coverages of road-village network for connecting between center places and rural villages as input data of the model. In order to verify the model algorithm, a homogeneous hexagonal network, assuming distribution of villages with same population density and equal distance between neighborhood villages on a level plane area, was tested to simulate the optimal paths between the selected center nodes and the other rear nodes, so that the test showed reasonable shortest paths and road intensity defined in this study. The model was also applied to the actual rural area, Ucheon-myun, which is located on Hoengsung-gun, Kangwon-do, with 72 rural villages, a center village (Uhang, 1st center place) in the area, a county conte. (Hoengsung-eup, 2nd center place), and a city (Wonju, 3rd center place), as upper settlement system. The three kinds of conte. place, Uhang, Hoengsung-eup, and Wonju, were considered as center places of three scenarios to simulate the optimal shortest paths between the centers and rural villages, respectively. The simulation results on the road-village network with road information about pavement and width of road show that several spans having high intensity of road are more important that the others, while some road spans have low intensity of road.

• Journal of Advanced Navigation Technology
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• v.17 no.5
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• pp.491-496
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• 2013

In this paper, a half-wavelength folded-slot antenna, which can be applied to RF module for 3G mobile communications by which security lights are monitored and controlled, is proposed. The proposed antenna can be regarded as modified folded-slot structure which has the size reduced to a half of conventional ${\lambda}g$ folded-slot antenna and can be placed at the ground plane edge. In spite of that, the proposed antenna still maintain the advantage of conventional folded-slot antenna that input impedance is close to $50{\Omega}$. The antenna is designed and fabricated within the upper space of $40.5{\times}10mm^2$ on $40.5{\times}62mm^2$ substrate for 3G mobile communication frequency band. The measured impedance bandwidth and antenna gain are 390 MHz and 2 dBi respectively.

• Korean Journal of Metals and Materials
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• v.48 no.8
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• pp.705-716
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• 2010

Effects of specimen thickness and notch shape on fracture mode appearing in drop weight tear test (DWTT) specimens of API X70 and X80 linepipe steels were investigated. Detailed microstructural analysis of fractured DWTT specimens showed that the fractures were initiated in normal cleavage mode near the specimen notch, and that some separations were observed at the center of the fracture surfaces. The Chevron-notch (CN) DWTT specimens had broader normal cleavage surfaces than the pressed-notch (PN) DWTT specimens. Larger inverse fracture surfaces appeared in the PN DWTT specimens because of the higher fracture initiation energy at the notch and the higher strain hardening in the hammer-impacted region. The number and length of separations were larger in the CN DWTT specimens than in the PN DWTT specimens, and increased with increasing specimen thickness due to the plane strain condition effect. As the test temperature decreased, the tendency to separations increased, but separations were not found when the cleavage fracture prevailed at very low temperatures. The DWTT test results, such as upper shelf energy and energy transition temperature, were discussed in relation with microstructures and fracture modes including cleavage fracture, shear fracture, inverse fracture, and separations.

• Korean Journal of Soil Science and Fertilizer
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• v.4 no.1
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• pp.67-73
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• 1971

This paper has been made for the soil micro-morphological study of Sirye series. The results are summarized as follows: 1. By high biological activity, soil materials are mixed. Pedotubules and Fecal pellets pedological features are formed by this activity. 2. There are no strong illuviation cutans. The formation of dirty cutans (new cutans) are due to sedimentation in furrow. 3. The relatively thick crystallization of goethite in plane voids are formed. 4. The lower parts of this soils are influenced by hydromorphology. 5. B3 horizon may be buried A horizon, containing the fragments of upper horizons.

• Clinical and Experimental Pediatrics
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• v.61 no.12
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• pp.392-396
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• 2018

Purpose: Adenotonsillar hypertrophy (ATH) that causes upper airway obstruction might lead to chronic hypoxemic pulmonary vasoconstriction and right ventricular (RV) dysfunction. We aimed to evaluate whether adenotonsillectomy (T&A) in children suffering from obstructive sleep apnea (OSA) due to severe ATH could improve RV function. Methods: Thirty-seven children (boy:girl=21:16; mean age, $9.52{\pm}2.20years$), who underwent T&A forsleep apnea due to ATH, were included. We analyzedthe mean pulmonary artery pressure (mPAP), the presence and the maximal velocity of tricuspid regurgitation (TR), the tricuspid annular plane systolic excursion (TAPSE), and the right ventricular myocardial performance index (RVMPI) with tissue Doppler echocardiography (TDE) by transthoracic echocardiography pre- and post-T&A. The follow-up period was $1.78{\pm}0.27years$. Results: Only the RVMPI using TDE improved after T&A ($42.18{\pm}2.03$ vs. $40{\pm}1.86$, P=0.001). The absolute value of TAPSE increased ($21.45{\pm}0.90mm$ vs. $22.30{\pm}1.10mm$, P=0.001) but there was no change in the z score of TAPSE pre- and post-T&A ($1.19{\pm}0.34$ vs. $1.24{\pm}0.30$, P=0.194). The mPAP was within normal range in children with ATH, and there was no significant difference between pre- and post-T&A ($19.6{\pm}3.40$ vs. $18.7{\pm}2.68$, P=0.052). There was no difference in the presence and the maximal velocity of TR (P=0.058). Conclusion: RVMPI using TDE could be an early parameter of RV function in children with OSA due to ATH.