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A Geometric Compression Method Using Dominant Points for Transmission to LEO Satellites
고광희,안효성,왕세명,최수진,정옥철,정대원,박형준 한국항공우주학회 2016 International Journal of Aeronautical and Space Sc Vol.17 No.4
In the operation of a low earth orbit satellite, a series of antenna commands are transmitted from a ground station to the satellite within a visibility window (i.e., the time period for which an antenna of the satellite is visible from the station) and executed to control the antenna. The window is a limited resource where all data transmission is carried out. Therefore, minimizing the transmission time for the antenna commands by reducing the data size is necessary in order to provide more time for the transmission of other data. In this paper, we propose a geometric compression method based on B-spline curve fitting using dominant points in order to compactly represent the antenna commands. We transform the problem of command size reduction into a geometric problem that is relatively easier to deal with. The command data are interpreted as points in a 2D space. The geometric properties of the data distribution are considered to determine the optimal parameters for a curve approximating the data with sufficient accuracy. Experimental results demonstrate that the proposed method is superior to conventional methods currently used in practice.
구개열(口蓋裂) 환자(患者)에 있어서 구개(口蓋) 성형술후(成形術後) 비인강(鼻咽腔) 폐쇄(閉鎖)에 관(關)한 임상적(臨床的) 연구(硏究)
고광희,신효근,Koh, Kwang-Hee,Shin, Hyo-Keun 대한악안면성형재건외과학회 1992 Maxillofacial Plastic Reconstructive Surgery Vol.14 No.1
In order to find the causes of velopharyngeal incompetency after primary palatorrhaphy in cleft patients, we analyzed the form and function of the velopharyngeal space of fifteen operated cleft palate patients and five normal subjects. The velopharyngeal function was evaluated by lateral cephalometric radiography, velopharyngography and hypernasality cul-de-sac test. The obtained results were as follows. 1. The rate of velopharyngeal incompetency was twenty percent, three of the fifteen operated patients. Two of them were complete cleft palate and the other was incomplete one. 2. The length of soft palate and levator eminence were longer in normal group than those of good speech group and complete cleft palate group during phonation of /i/ (P<0.05). The lengthening rate of soft palate was smaller in good and poor speech group than that of normal group(P<0.05), and, reduced in order, normal group, complete cleft palate group and incomplete palate group(P<0.05). 3. The nasopharyngeal distance had no significant difference between all groups at rest, but, smaller in normal group than that of both cleft palate group(P<0.05), good speech group and poor speech group(P<0.05) during phonation of /i/ The difference in nasopharyngeal distance between rest and /i/ phonation was greater in normal group than that of both cleft palate group, good speech group and poor speech group. 4. The moving distance of sop palate reduced in order, normal group, incomplete cleft palate group, complete cleft palate group(P<0.05). 5. The distance between lateral pharyngeal wall had no significant difference between all groups in rest, but, smaller than that of complete cleft palate group in normal group(P<0.01) and increased in order normal group, good speech group, poor speech group(P<0.01) during phonation of /a/. The mobility of lateral wall was reduced in order, normal group, good speech group poor speech group(P<0. 01). 6. There was low corelationship between the mobility of lateral pharyngeal wall and soft palate. Therfore, it suggest that the movements of lateral pharyngeal wall and soft palate occurs independently.
Synthesis and Guest Binding Properties of Cyclophanes Containing Two Benzo[b]furan Rings
고광희,Sun-Hyuk Kim,박준우 대한화학회 2004 Bulletin of the Korean Chemical Society Vol.25 No.11
The cyclophanes 1a-d containing two benzo[b]furan rings connected by various bridges have been prepared and their binding behaviors with N-benzylphenethylammonium cation 2 were examined by NMR titration method. The successive alkylation reactions of 4-hydroxyl groups and then 2-hydroxyl groups of 2,4-dihydroxybenzophenonse gave macrocycles 5a-c. Photoirradiation of the macrocycles 5a-c with 350 nm mercury lamp followed by dehydration afforded the cyclophanes 1a-c. Hydrolysis of two ester groups pendant on a bridge of 1b produced the carboxyl group-containing cyclophane 1d. The cyclophane 1a having a p-xylene bridge showed 1 : 1 binding with 2 with the binding constant of 36 ± 6 M−1 in 3 : 1 CDCl3/methanol-d4 solvent, while 1b and 1c which have neutral flexible bridges exhibited no appreciable binding with 2. The disodium salt of 1d showed much higher binding affinity for 2 forming 1 : 1 and 1 : 2 complexes.
A Survey: application of geometric modeling techniques to ship modeling and design
고광희 대한조선학회 2010 International Journal of Naval Architecture and Oc Vol.2 No.4
In this study, geometric modeling techniques and their application to ship modeling and design are presented. Traditionally the hull shape is defined by using curves called the lines and various necessary computations are performed based on the discrete points obtained from the lines. However, some applications find difficulty in using the lines such as seakeeping analysis, which requires the computation of wetted part that is changing dynamically over time. To overcome such a problem and increase accuracy and efficiency in computation, two essential geometric modeling techniques, surface modeling and surface-to-surface intersection, are introduced and their application to ship modeling and analysis including hydrostatic computation, slamming and seakeeping analyses is presented.
Development of software for computing forming information using a component based approach
고광희,박정서,김영범,신종계,김정 대한조선학회 2009 International Journal of Naval Architecture and Oc Vol.1 No.2
In shipbuilding industry, the manufacturing technology has advanced at an unprecedented pace for the last decade. As a result, many automatic systems for cutting, welding, etc. have been developed and employed in the manufacturing process and accordingly the productivity has been increased drastically. Despite such improvement in the manufacturing technology, however, development of an automatic system for fabricating a curved hull plate remains at the beginning stage since hardware and software for the automation of the curved hull fabrication process should be developed differently depending on the dimensions of plates, forming methods and manufacturing processes of each shipyard. To deal with this problem, it is necessary to create a "plug-in" framework, which can adopt various kinds of hardware and software to construct a full automatic fabrication system. In this paper, a framework for automatic fabrication of curved hull plates is proposed, which consists of four components and related software. In particular the software module for computing fabrication information is developed by using the ooCBD development methodology, which can interface with other hardware and software with minimum effort. Examples of the proposed framework applied to medium and large shipyards are presented.
소아의 무딘 경추손상에 대한 영상검사 현황 및 임상의사결정규칙 적용
고광희,이현정,김현준,신태용,이동욱,문형준,정동길 대한소아응급의학회 2023 대한소아응급의학회지 Vol.10 No.2
Purpose: We investigated the current status of imaging studies for pediatric blunt cervical spine injury, and applied 3 clinical decision rules to children with blunt trauma of the head or neck in a pediatric emergency center in Korea. The rules included National Emergency X-Radiography Utilization Study (NEXUS) criteria, Canadian Cervical Spine Rule, and Pediatric Emergency Care Applied Research Network risk factors. Methods: This was a retrospective study conducted on 399 children aged 15 years or younger who visited the center after the blunt trauma, and underwent cervical spine radiographs from January 2020 through December 2021. We examined the clinical characteristics per age groups (0-1, 2-5, 6-12, and 13-15 years). Using the 3 rules, we selected children with a potential need for imaging studies (PNI). For this purpose, we analyzed the absence of low-risk variables and the presence of high-risk variables. Predictive performances of the rules were measured for the imaging-confirmed cervical spine injury. Results: The study population (n = 399) had a median age of 5.0 years (interquartile range, 2.0-9.0) and a 64.2% boys’ proportion. Fall (36.6%) was the most common injury mechanism. Two children had the cervical spine injuries. As per NEXUS criteria, Canadian Cervical Spine Rule, and Pediatric Emergency Care Applied Research Network risk factors, 72 (18.0%), 289 (72.4%), and 74 children (18.5%) were classified as those with PNI, respectively. Resultantly, 291 children (72.9%) were classified as having PNI whereas the other 108 (27.1%) were deemed to undergo unnecessary imaging. The 3 rules had nearly 100% sensitivity and negative predictive value, except a 50% sensitivity of NEXUS criteria. Conclusion: Imaging studies can be minimized for children with blunt trauma of the head or neck who are deemed without PNI per the 3 current clinical decision rules. More elaborate criteria are needed to make a timely diagnosis.