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Anatomic Study of Pterygomaxillary Junctions in Koreans

  • Kim, Dong-Yul;Cho, Yeong-Cheol;Sung, Iel-Yong;Yun, Dae-Kawn;Kim, Min-Uk;Kim, Ji-Uk;Son, Hyung-Suck;Son, Jang-Ho
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.35 no.6
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    • pp.368-375
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    • 2013
  • Purpose: This study is to evaluate the location of descending palatine artery, the anatomy of pterygomaxillary junction, and the association between the obtained anatomic values and several variables. Methods: We studied 40 patients who were treated for dentofacial deformites from January 2010 to December 2012 in Ulsan University Hospital, Ulsan, Korea. Cone beam computed tomogram (CBCT) was done for all patients. The reference point was approximately 5 to 7 mm above anterior nasal spine on axial image. We evaluated the location of the greater palatine canal (line a: on the coronal view, the shortest line between the center of greater palatine canal and pterygoid fossa; distance a: the distance of line a). We also measured the thickness (line b: on the coronal view, the shortest line between maxillary posterior sinus wall and pterygoid fossa; distance b: distance of line b), width (line c: on the coronal view, the line perpendicular to the line b and the nearest line from the most concave point of lateral pterygoid plate to the medial pterygoid plate; distance c: distance of line c) and height (line d: on sagittal view, the vertically longest line of pterygoid junction; distance d: the distance of line d) in pterygomaxillary junctions. We evaluated the association between the obtained anatomic values and several variables (sex, age, height and weight). Results: The mean distance a was 4.78 mm, mean distance b was 5.53 mm, mean distance c was 8.01 mm and mean distance d was 13.22 mm. The differences between age and mean distance c and weight and mean distance d in pterygomaxillary junctions are statistically significant. Conclusion: There apparently is anatomic variation of pterygomaxillary junctions by various values, particularly weight and age in a Korean clinical population.

A Study on Development of the Low Electrical Power Echo Sounder System for Coastal Use (연안목적용 저출력 어군탐지기 음향계의 개발에 관한 연구)

  • Park, Ju-Sam
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.15 no.3
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    • pp.243-250
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    • 2009
  • The expression of signal to noise ratio (SNR) is derived for the individual echo sounder and for the general specifications of commercial echo sounder. The SNR is depicted by several factors on transmitting and receiving, sound propagation, scattering by fishes, and mainly self ship noise. The detection ranges of echo sounders in depth and breadth are derived by finding the border of an acceptable SNR. The detection ranges are computed for the echo sounders of individual and general specifications. Generally, the detection range is lager for low frequencies. Increasing an electrical power and a diameter of transducer is not as effective for high frequencies as for low frequencies to increase the detection range. The theoretical results of the detection range can be applied to design low electrical power echo sounder for coastal use, to select an appropriate echo sounder, to know the capability of a sounder, and to interpret echograms. A method for evaluating and designing low electrical power echo sounder is developed. A universal diagram for the basic design of the low electrical power echo sounder where SNR is plotted against frequency is developed. An appropriate frequency, transducer diameter, and beam width are easily determined by using the diagram.

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Measurement of picosecond laser pulsewidth and pulseshape by two-photon fluorescence and noncolloinear type I second harmonic generation method (이광자 형광법과 비공선 일종 이차고조파법에 의한 피코초 레이저 펄스폭과 펄스형 측정)

  • 한기호;박종락;이재용;김현수;엄기영;변재오;공흥진
    • Korean Journal of Optics and Photonics
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    • v.7 no.3
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    • pp.251-259
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    • 1996
  • Two-Photon Fluorescence (TPF) experiment measures temporal width of an amplified short laser pulse which has passed through a four-pass Nd: glass amplifier, after selecting a single pulse from pulse train Q-switched and mode-locked(QSML) in Nd:YLF master oscillator. Determination of pulsewidth and pulseshape was also made with detection of autocorrelation trace of CW mode-locked pulse train by using noncollinear type I Second Harmonic Generation (SHG) method. The observed TPF track showed various patterns, depending on pulse-selecting position in QSML pulse train. That is, autocorrelation of a pulse extracted at front of the train displayed smooth pulse shape, while one from the trailing part of the train created many sharp spikes and substructure in the pulse. By TPF method, pulsewidth was measured to be 44.4 ps with contrast ratio of 2.86 which enabled us to find out energy fraction of a pulse to total energy, (sum of pulse and background); we obtain the value of 0.62. Pulsewidth of 46.6ps was also acquired in another SHG experiment with the help of only mode-locked pulse train. On the other hand, we confirmed that shape of the pulse is close to $sech^2$ one as a result of fitting the SHG autocorrelation signal with various functions. With simulation using this $sech^2$ type of pulse, pulsewidth reduction of the beam, having passed through four-pass amplifier, was also verified.

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The Effect of Mild Tensile Reinforcement and Effective Prestress on the Flexural Performance of the Prestressed Lightweight Concrete Beams with Unbonded Tendons (비부착 프리스트레스트 경량 콘크리트 보의 휨 거동에 대한 부착 철근과 유효 프리스트레스의 영향)

  • Mun, Ju-Hyun;Yang, Keun-Hyeok;Byun, Hang-Yong
    • Journal of the Korea Concrete Institute
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    • v.23 no.5
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    • pp.617-626
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    • 2011
  • Seven post-tensioned lightweight concrete (LWC) beam specimens were tested under a symmetrical two-point top loading system. The parameters investigated were the amounts of mild longitudinal reinforcement and effective prestressing. The design compressive strength and dry density of the LWC tested were 30 MPa and 1,770 $kg/m^3$, respectively. Similar to post-tensioned normal weight concrete (NWC) beams, the crack propagation and stress increase of the unbonded tendons were significantly affected by the amounts of mild longitudinal reinforcement and effective prestressing. With the increase in the amounts of mild longitudinal reinforcement and effective prestressing, the serviceability and flexural capacity of the beams were enhanced whereas the stress increase in the unbonded tendons decreased. To control the crack width in post-tensioned LWC beams, a minimum amount of mild longitudinal reinforcement specified in ACI 318-08 provision is required. The flexural behavior of post-tensioned LWC beams and stress increase of the unbonded tendons could be rationally predicted by the proposed non-linear two-dimensional analysis. On the other hand, ACI 318-08 flexure provision was too conservative about the post-tensioned LWC beams.

A Study on the Optimal Design of Reinforced Concrete Frames Using SUMT (SUMT 법(法)을 이용(利用)한 철근(鐵筋)콘크리트 뼈대구조물(構造物)의 최적설계(最適設計)에 관한 연구(研究))

  • Jung, Young Chae;Lee, Qyu Won
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.4 no.1
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    • pp.27-48
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    • 1984
  • This study is conserned with the optimization of reinforced concrete frames using limit state design theory. Formulations of the optimal design for reinforced concrete frame based on the limit state theory turn out to be the nonlinear programming problems which have to deal with the required steel area, the width and effective height of the beam and column section and the moment reduction factor as the design variables. The objective function is formulated as the total construction cost which considers the costs of steel, concrete and forming for the reinforced concrete frames, and the basic constraints are imposed upon both ultimate and serviciability limit state concepts. Also, the stress blocks assumpted in CP110 and Hognestad et al. theory are applied to analysis an ultimate resistant section force for the ultimate limit state and only the criteria of CP110 are used for serviciability limit state. The optimized technique which is applied to solve the nonlinear programming problems for the optimization of reinforced concrete frames is SUMT utilizing the modified Newton-Raphson method. This algorithm is used to test for the two reinforced concrete frames, and then is compared and analysized with the numerical results of reference(10) to examine its convergence, applicability and stability under the same conditions. The results of this study are discussed about the economy comparision of the optimal values for CP110 and Hognestad et al., and the applicability, stability, convergence and validity of this algorithm used herein through the numerical analyses.

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Material Properties of Polymer-Impregnated Concrete and Nonlinear Fracture Analysis of Flexural Members (폴리머 침투콘크리트의 재료특성과 휨부재의 비선형 파괴해석)

  • 변근주;이상민;최홍식;노병철
    • Magazine of the Korea Concrete Institute
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    • v.6 no.2
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    • pp.97-107
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    • 1994
  • The objective of this study is to develop polymer-impregnated concrete(PIC), which is a newly developed composite material made by impregnating polymer impregnanls into hardened normal concrete, and to develop analytical techniques for its proper applications. Crystalline methyl methacrylate(MMA) is chosen as a monomer of polymer impregnants. The corrlpositions of polymer impregnants and producing processes are developed by analyzing the effects of penetration, polymerization, thermal safety, and strengthening characteristics. On t he basis of experimental results of this study, various strength characteristics and stress strain constitutive relations are formulated in terms of the compressive strength of normal concrete and the polymer loadings, which can be applied for analysis and design of PIC members. In order to provide a model for fracture analysis of flexural members, fracture toughness, fracture energy, critical crack width, and tension softening relations near crack tip are also formulated in terms of member depth, initial notch depth, and the flexural strength of normal concrete. The structural analysis procedure and the finite element computer program developed in the study are applicable to evaluate elastic behavior, ultimate strength, and tension softening behavior of MMA type PIC structural members subject to various loading conditions. The accuracy and effectiveness of the developed computer program is examined by comparing the anal ytical results with the experimental results. Therefore, it is concluded that the developed structural analysis procedure and the finite element computer program are applicable to analysis and design of in-situ and precast PIC structural members.

Design of Dual-Polarization Antenna with High Cross-Polarization Discrimination (높은 교차편파 분리도를 가지는 이중편파 안테나 설계)

  • Lee, Sang-Ho;Oh, Taeck-Keun;Ha, Jung-Je;Lee, Yong-Shik
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.10 no.3
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    • pp.199-205
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    • 2017
  • In a small cell base station used in densely populated areas, a dual polarized multiple antenna(MIMO) is mainly used to increase the cell capacity. This paper demonstrates a dual-polarization antenna with high cross-polarization discrimination(XPD) that can improve the capacity of a small cell using a dual polarization multiple antenna (MIMO). By using the symmetric structure and differential feeding, high XPD in all directions is achieved. In addition, a very similar radiation pattern is observed between each polarization. Because of high XPD and similar radiation pattern in all directions, proposed antenna is well adopted for small-cell multiple-input multiple-output(MIMO) system. Experimental results shows that the proposed antenna has a bandwidth of 180 MHz (2.51~2.7 GHz), a maximum gain of 4.5 dBi (3.5~4.5 dBi), and a half-power beam width of 85 degrees. In addition, average XPD of 26.4 dB in all directions, more than 13.8 dB increase than previous dual-polarization antennas which use single emitter by using different feeding or selectively use polarization through switching.

Requirement Analysis of Satellite On-the-Move Transportable Terminal System (이동통신형 차량위성단말 시스템 요구사항 분석)

  • Oh, Il-Hyuk;Song, Choong-Ho;Ko, Dong-Kuk
    • Journal of Satellite, Information and Communications
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    • v.3 no.1
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    • pp.41-47
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    • 2008
  • Line-of-sight communications cannot easily support korean armed forces because of mountainous terrain. ADD(Agency for Defense Development) introduced ANASIS(Army Navy Air-force Satellite Information System) to meet the Korean warfighter's operational needs. Currently, army's military satcom terminal is designed for either fixed site or on-the-pause operation. The US army is under development of multi-band integrated on-the-move satellite terminals to let the army's communication capability to keep pace with globally deployable Joint Task Force for network-centric application. In this paper we analyzed X-band and Ka-band link and subsystem requirement. Our focus here is to describe key technical issues. Especially, On the basis of 3dB beam width of 0.9m antenna, Tracking accuracy and disturbances compensation signal processing on-the-move of Antenna Tracking system is analyzed. Also, protocol is analyzed that minimize blockage on the move due to an obstacle. when the received signal blocked, it stop to transmit burst signal and retransmit when blockage removed through received synchronization signal monitoring. Analyzed specification will be used to make prototype terminal to analyze risk for mass production

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Design of V-Band Waveguide Slot Sub-Array Antenna for Wireless Communication Back-haul (무선통신 백-홀용 V-밴드 도파관 슬롯 서브-배열 안테나의 설계)

  • Noh, Kwang-Hyun;Kang, Young-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.7
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    • pp.334-341
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    • 2016
  • In this paper, the study of a waveguide aperture-coupled feed-structured antenna has been conducted for the purpose of applying it to a wireless back-haul system sufficient for high-capacity gigabits-per-second data rates. For this study, a $32{\times}32$ waveguide slot sub-array antenna with a corporate-feed structure was designed and produced. Also, this antenna is used at 57 GHz to 66 GHz in the V-band. The construction of the antenna is a laminated form with radiating parts (outer groove and slot, cavity), a coupled aperture, and feeds in each. The antenna was designed with HFSS, which is based on 3D-FEM, produced with aluminum processed by a precision-controlled milling machine, and assembled after a silver-plating process. The measurement result from analysis of the characteristics of the antenna shows that return loss is less than -12 dB, VSWR < 2.0, and a wide bandwidth ranges up to 16%. An overall first side lobe level is less than -12.3 dB, and a 3 dB beam width is narrow at about $1.85^{\circ}$. Also, antenna gain is 38.5 dBi, offering high efficiency exceeding 90%.

Comparison of Behavior of Connections between Modular Units according to Shape of Connector Plates (연결 강판 형상에 따른 모듈러 유닛 간 접합부의 거동 비교)

  • Lee, Sang Sup;Bae, Kyu Woong;Park, Keum Sung
    • Journal of Korean Society of Steel Construction
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    • v.28 no.6
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    • pp.467-476
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    • 2016
  • For the connections between modular units in modular buildings, the bolted joints with connector plates are used commonly. The strength of structure is determined by the weakest part of structure and the connections may be weaker than the members being joined. Therefore, to check the safety of modular building, the structural performance of connections between modular units as well as that of beam-to-column connections should be evaluated. In this study, the behavior of module to module connection with straight and cross shaped connector plates is investigated by lateral cyclic tests according to KBC2009 0722.2.4 which shall be conducted by controlling the story drift angle in the width and the longitudinal direction respectively. All of test results generally show the stable ductile behavior up to 0.04rad drift levels and the tests in longitudinal direction show a superior energy dissipation per cycle in each of the load steps. However, the straight shaped connector plates have the degradation of stiffness with cyclic loading and the larger drift angle of column than the cross shaped connector plates.