• Fisheries and Aquatic Sciences
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• 제27권1호
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• pp.1-6
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• 2024

In this study, the swimming behavior of a small box jellyfish (Carybdea brevipedalia), which consists of inhaling external seawater and expelling it through its mouth to generate forward thrust, was characterized using particle image velocimetry (PIV). The flow rate and structure during the suction and discharge process were quantitatively analyzed. During swimming, there was a change in the ratio of the internal area during inhalation and expulsion. Specifically, there was a 1.10-fold difference between the maximum area after inhalation and the minimum area after discharge. The maximum distance traveled after discharge was inversely proportional to the size of the inner area, with a 2.48-fold difference in the minimum distance traveled after suction. Depending on the propulsion stage, the inner area decreased and then increased in proportion to the moving distance and speed. The moving distance of the small box jellyfish was measured for each period. The speed for each swimming stage increased and then decreased at intervals of 0.15 to 0.2 seconds, and the suction and discharge cycle period was measured at approximately 0.5 seconds. Collectively, our findings provide a methodological basis for studying the swimming behavior of small and highly active trailing jet jellyfish, as well as the biological mechanisms that determine this behavior.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.461-462
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• 2009

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제40권4호
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• pp.169-172
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• 2014

Objectives: The purpose of this retrospective study was to compare the amount of postoperative drainage via closed suction drainage system after intraoral vertical ramus osteotomy (IVRO) and sagittal split ramus osteotomy (SSRO). Materials and Methods: We planned a retrospective cohort study of 40 patients selected from a larger group who underwent orthognathic surgery from 2007 to 2013. Mean age (range) was 23.95 (16 to 35) years. Patients who underwent bilateral IVRO or SSRO were categorized into group I or group II, respectively, and each group consisted of 20 patients. Closed suction drainage system was inserted in mandibular osteotomy sites to decrease swelling and dead space, and records of drainage amount were collected. The data were compared and analyzed with independent t-test. Results: The closed suction drainage system was removed at 32 hours postoperatively, and the amount of drainage was recorded every 8 hours. In group I, the mean amount of drainage was 79.42 mL in total, with 31.20 mL, 19.90 mL, 13.90 mL, 9.47 mL, and 4.95 mL measured at 0, 8, 16, 24, and 32 hours postoperatively, respectively. In group II, the mean total amount of drainage was 90.11 mL, with 30.25 mL, 25.75 mL, 19.70 mL, 8.50 mL, and 5.91 mL measured at 0, 8, 16, 24, and 32 hours postoperatively, respectively. Total amount of drainage from group I was less than group II, but there was no statistically significant difference between the two groups (P=0.338). There was a significant difference in drainage between group I and group II only at 16 hours postoperatively (P=0.029). Conclusion: IVRO and SSRO have different osteotomy design and different extent of medullary exposure; however, our results reveal that there is no remarkable difference in postoperative drainage of blood and exudate.

• 한국태양에너지학회 논문집
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• 제30권6호
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• pp.137-143
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• 2010

In this study, the ejector design was modeled using Fluent 6.3 of FVM(Finite Volume Method) CFD(Computational Fluid Dynamics) techniques to resolve the flow dynamics in the ejector. A vacuum system with the ejector has been widely used because of its simple construction and easy maintenance. Ejector is the main part of the desalination system, of which designs determine the efficiency of system. The effects of the ejector was investigated geometry and the operating conditions in the hydraulic characteristics. The ejector consists mainly of a nozzle, suction chamber, mixing tube(throat), diffuser and draft tube. Liquid is supplied to the ejector nozzle, the fast liquid jet produced by the nozzle entrains and the non condensable gas was sucked into the mixing tube. In the present study, the multiphase CFD modeling was carried out to determine the hydrodynamic characteristics of seawater-air ejector. Two-dimensional geometry was considered with the quadrilateral-mashing scheme. The gas suction rate increases with increasing Motive flow circulating rate.

• 유기물자원화
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• 제24권3호
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• pp.63-74
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• 2016

본 연구는 돈분 퇴비화 시 공기흡입 시스템을 적용한 반응기 내 퇴비의 이화학적 성상을 조사하기 위하여 실시되었다. 본 연구에서는 톱밥을 수분조절재로 이용하여 돼지분뇨와 적절하게 혼합한 후, 총 용적 30 L 크기의 플라스틱 재질 반응기에서 실험을 수행하였다. 공기펌프를 이용하여 반응기 하단부에서 공기를 주입하였으며, 진공흡입펌프를 이용하여 반응기 상단부, 중앙 측면부, 하단부에서 각각 공기를 흡입 할 수 있게 설비하였다. 온도의 경우, 퇴비화 개시 후 3일 째에 $58^{\circ}C{\sim}62^{\circ}C$로 가장 높게 관찰되었으며, 모든 시험구가 3일간 $50^{\circ}C$ 이상의 온도를 유지하는 것을 관찰할 수 있었다. 퇴비의 온도는 점차 안정화 되어 60일 이후 대기 온도와 비슷하게 감소했다. 퇴비단 표면에서 발생하는 암모니아는 대조구를 제외하고 퇴비화 개시 4일 째에 각각 상부흡입조건 : 500 ppm, 하부흡입조건 162 ppm, 중앙 측면흡입조건 120 ppm 순으로 가장 높은 발생량이 조사되었다. 퇴비 표면에서 발생한 암모니아의 경우, 상부흡입 처리구가 타 처리구에 비해 상대적으로 높은 암모니아 발생량을 보였다. 총 켈달질소 함량 (TKN)은 퇴비단의 질량 감소에 의해 점점 증가하는 것을 관찰할 수 있었고, C/N비는 초기 퇴비단이 23 이었으며, 퇴비화가 진행되면서 점차 감소해 최종적으로는 상부흡입조건 13, 중앙 측면흡입조건 12, 하부흡입 13으로 관찰되었다. $NH_4-N$ 과 $NO_3-N$의 비율은 퇴비화 개시 시 10.52였으며, 점차 감소하여 퇴비화 종료일에 상부흡입조건 0.97, 중앙 측면흡입조건 0.70, 하부흡입조건 3.2로 관찰되었다. 결과적으로 상부흡입조건과 중앙 측면흡입 조건이 양질 퇴비를 만들기 위한 최적의 조건인 것으로 관찰되었다.

• 수산해양기술연구
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• 제43권3호
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• pp.212-221
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• 2007

This paper describes on the evaluation and management of work process in suction hopper dredger and grab bucket dredger as an application of a PC-based ECDIS system. The dynamic tracking of dredging bucket and the data logging of grab dredging information were performed by using the grab dredging vessel "Kunwoong G-18". The position and route tracking of the dredger moving toward the ocean dumping site of dredged material was performed by using the hopper dredging vessel "Samyang-7". The evaluation of wok process in the dredging field, for grab dredger, was continuously carried out on January to May, 2006, in Incheon Hang and for hopper dredger, on July to December, 2003, in Busan Hang, Korea. The dredging information, such as dredger's position, heading, dredging depth and route track which was individually time stamped during the dredging operation, was automatically processed in real-time on the ECDIS and displayed simultaneously on the S-57 ENC chart. From these results, we conclude that the ECDIS system can be applied as a tool in order to manage the work process during the dredging operation, and also in order to generate the factual record of the dredging activities that is sufficient for dredging inspector to accurately evaluate the contract performance even in the absence of a full-time onboard inspector.

• 설비공학논문집
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• 제4권4호
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• pp.306-315
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• 1992

This paper addresses performance analysis of a reciprocating compressor. A computer simulation model has been developed to predict and estimate the compressor performance. Instead of using ideal gas equations, real gas equations are used in describing the state of gas. The compressor simulation model consists of a cylinder control volume, suction system and discharge system. Conservation laws of mass and energy are applied to the cylinder section only, The suction and discharge system are described by the Helmholtz resonator modeling. Some of input data required for the simulation have been obtained from experiments. These experimentally obtained input data are effective flow area, effective force area and dynamic characteristics of valves. Simulation results of real gas equations have been compared with those of ideal gas equations. It has been found that the simulation with real gas equations yields lower cylinder temperature and heat transfer compared with those of ideal gas equations. Differences in pressure, mass flowrates, valve motions and gas pulsations are found quite small.

• 한국안전학회지
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• 제7권3호
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• pp.30-34
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• 1992

This study is conducted to evaluate the airborne concentration of mercury, as well as installation and efficiency of local exhaust ventilation system for 57 factories manufactured fluorescence lamps, mercury lamps and thermometers for July and August 1990. Results and conclusion are as fellows : 1) Mercury treatment factories are 32 among 57 ones, which are 18 fluorescence lamp manufacturing ones and 6 mercury lamp ones and 3 thermometer ones and 5 other ones. 2) Mean airborne concentrations of mercury for factories manufactured mercury lamps are 0.01 mg/ ㎥ in injection process and 0.0155mg/㎥ in exhaust process, and mean airborne concentration of mercury for factories manufactured thermometer are 0.023mg/㎥ in injection process and 0.012mg/㎥ in selection process. All of these airborne concentrations of mercury are lower than PEL(Permissible Exposure Limit ), 0.05mg/㎥. 3) Mean airborne concentrations of mercury for factories manufactured fluorescence lamps are 0.094mg/㎥ in injection process and 0.087mg/㎥ in exhaust process, and 0.052mg/㎥ in sealing process and 0.085mg/㎥ in other process, respectively. All of these air borne concentrations of mercury are exceeded to PEL. More than 60% among 32 factories manufactured mercury are exceeded to PEL. 4) Nine factories among 18 factories manufactured fluorestence lamps are equipped with local exhaust ventilation system, and 7 factories among 9 factories are required for the improvement of suction capacity and structure. Five factories among 14 factories manufactured mercury lamps and the other ones are equipped with local exhaust ventilation system, and 2 factories are required for the improvement of suction capacity and structure.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2011년도 추계학술대회
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• pp.541-543
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• 2011

고령화 사회의 노인성 질환 치료기술에 대한 수요가 증가되고 있는 가운데 최근 한의약이 새롭게 주목을 받고 있다. 본 논문에서는 환자 스스로 의해 기본적인 치료가 이루어질 수 있는 휴대용 한방 멀티 전동 부항 시스템을 제안했다. 본 시스템은 여러 개의 부항컵을 동시에 시술할 수 있고, 타이머와 공압을 자유롭게 조절하여 환부의 장시간 공압 유지로 인한 가려움증 및 근육응결을 해소할 수 있다.

• 한국산학기술학회논문지
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• 제18권4호
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• pp.544-549
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• 2017

본 논문은 오존 방식 선박평형수 처리의 핵심 장치인 이젝터에 대하여 회전 운동하는 구동 유체가 기체-액체 이젝터의 효율에 미치는 영향에 관한 연구이다. 이젝터는 오존을 구동 노즐을 통해 분사되는 고압 액체(선박평형수)와 주변부의 저압 기체 간의 운동량 교환으로 발생되는 부압에 의해 기체(오존)를 흡입시키는 장치이다. 기존의 이젝터는 단순한 형태로 구동 유체가 분사되지만, 본 논문에서는 구동 노즐부에 회전 유도장치를 적용하여 구동 유체가 회전 운동하며 분사될 수 있도록 한다. 구동 유체의 회전 운동 유무에 따른 유동 특성을 파악하기 위하여 전산유체해석을 이용하였으며, 구동 유체의 압력과 유량, 흡입부에 발생하는 흡입 유체의 부압과 흡입 유량, 그리고 토출 압력이 예측되었다. 그 결과를 바탕으로 회전유도 장치가 적용된 이젝터의 효율은 22.25%로 산출되었으며, 구동 유체의 회전 운동이 없는 이젝터에 비해 약 1.7%의 효율이 향상되었다. 마지막으로 전산유체해석의 타당성을 검증하고자 실험 장치를 구축하여 회전 유도 장치가 적용된 이젝터에 대한 실험을 수행하였으며, 전산유체해석 결과와 비슷한 결과를 얻을 수 있었다.