응급실로 내원한 비골골절환자에 대한 임상적 고찰

박동우,장혁순,강주원 대한이비인후과학회 1988 대한이비인후과학회지 두경부외과학 Vol.31 No.6

A study on the effect of flat plate friction resistance on speed performance prediction of full scale

박동우 대한조선학회 2015 International Journal of Naval Architecture and Oc Vol.7 No.1

Flat plate friction lines have been used in the process to estimate speed performance of full-scale ships in model tests. The results of the previous studies showed considerable differences in determining form factors depending on changes in plate friction lines and Reynolds numbers. These differences had a great influence on estimation of speed performance of full-scale ships. This study was conducted in two parts. In the first part, the scale effect of the form factor depending on change in the Reynolds number was studied based on CFD, in connection with three kinds of friction resistance curves: the ITTC-1957, the curve proposed by Grigson (1993; 1996), and the curve developed by Katsui et al. (2005). In the second part, change in the form factor by three kinds of friction resistance curves was investtigated based on model tests, and then the brake power and the revolution that were finally determined by expansion processes of full-scale ships. When three kinds of friction resistance curves were applied to each kind of ships, these were investigated: differences between resistance and self-propulsion components induced in the expansion processes of fullscale ships, correlation of effects between these components, and tendency of each kind of ships. Finally, what friction resistance curve was well consistent with results of test operation was examined per each kind of ships.

인공지능 기법에 의한 최적 운항자세 선정에 관한 연구

박동우 해양환경안전학회 2023 해양환경안전학회지 Vol.29 No.6

The selection technique for optimal operation position selection technique is used to present the initial bow and stern draft with minimum resistance, for achievingthat is, the optimal fuel consumption efficiency at a given operating displacement and speed. The main purpose of this studypaper is to develop a program to select the optimal operating position with maximum energy efficiency under given operating conditions based on the effective power data of the target ship. This program was written as a Python-based GUI (Graphic User Interface) usingbased on artificial intelligence techniques sucho that ship owners could easily use the GUIit. In the process, tThe introduction of the target ship, the collection of effective power data through computational fluid dynamics (CFD), the learning method of the effective power model using deep learning, and the program for presenting the optimal operation position using the deep neural network (DNN) model were specifically explained. Ships are loaded and unloaded for each operation, which changes the cargo load and changes the displacement. The shipowners wants to know the optimal operating position with minimum resistance, that is, maximum energy efficiency, according to the given speed of each displacement. The developed GUI can be installed on the ship's tablet PC and application and used to determineselect the optimal operating position.

두 개강내 급성백혈병의 전산화단층촬영술 소견

박동우 대한영상의학회 1990 대한영상의학회지 Vol.26 No.3

Computed tomographic (CT) abnormalities in the brain were retrospectively analyzed in 16 of 103 patients with acute leukemia confirmed by CSF cytology or combined surgery at Hanyang University Hospital, from August 1980 to August 1989. The results were as follows : 1. With FAB classification, the most frequent pathologic type was L1:8 cases505) 2. The range of age distribution showed typical pattern that ALL occurred below the 15 years old, and AML< over 15 years old. 3. Abnormal Ct findings were; Meningitis(2 cases0, Mass(3), Thrombosis(1), Infarction(2), Edema(1), Hemorrhage(7), Hydrocephalus(2), Atrophy(2) 4. Most of intracranial hemorrhage were seen in M2 and M3 type.

격자, 난류모형 및 이산화 방법이 유동해석 결과에 미치는 영향

박동우,윤현식,Park, Dong-Woo,Yoon, Hyun-Sik 해양환경안전학회 2014 해양환경안전학회지 Vol.20 No.4

The current work investigated the variation of numerical solutions according to the grid number, the distance of the first grid point off the ship surface, turbulence modeling and discretization. The subject vessel is KVLCC. A commercial code, Gridgen V15 and FLUENT were used the generation of the ship hull surface and spatial system and flow computation. The first part of examination, the effect of solutions were accessed depending on the grid number, turbulence modeling and discretization. The second part was focus on the suitable selection of the distance of the first grid point off the ship surface: $Y_P+$. When grid number and discretization were fixed the same value, the friction resistance showed differences within 1 % but the pressure resistance showed big differences 9 % depending on the turbulence modeling. When $Y_P+$ were set 30 and 50 for the same discretization, friction resistance showed almost same results within 1 % according to the turbulence modeling. However, when $Y_P+$ were fixed 100, friction resistance showed more differences of 3 % compared to $Y_P+$ of 30 and 50. Whereas pressure resistance showed big differences of 10 % regardless of turbulence modeling. When turbulence modeling and discretization were set the same value, friction, pressure and total resistance showed almost same result within 0.3 % depending on the grid number. Lastly, When turbulence modeling and discretization were fixed the same value, the friction resistance showed differences within 5~8 % but the pressure resistance showed small differences depending on the $Y_P+$.

AI 기반 설계 탐색 기법을 통한 선박의 주요 치수 최적화

박동우,김인섭 해양환경안전학회 2022 해양환경안전학회지 Vol.28 No.7

In the present study, the optimization of the main particulars of a ship using AI-based design search techniques was investigated. For the design search techniques, the SHERPA algorithm by HEEDS was applied, and CFD analysis using STAR-CCM+ was applied for the calculation of resistance performance. Main particulars were automatically transformed by modifying the main particulars of the ship at the stage of preprocessing using JAVA script and Python. Small catamaran was chosen for the present study, and the main dimensions of the length, breadth, draft of demi-hull, and distance between demi-hulls were considered as design variables. Total resistance was considered as an objective function, and the range of displaced volume considering the arrangement of the outfitting system was chosen as the constraint. As a result, the changes in the individual design variables were within ±5%, and the total resistance of the optimized hull form was decreased by 11% compared with that of the existing hull form. Throughout the present study, the resistance performance of small catamaran could be improved by the optimization of the main dimensions without direct modification of the hull shape. In addition, the application of optimization using design search techniques is expected for the improvement in the resistance performance of a ship. 본 논문에서는 AI 기반 설계 탐색 기법을 활용하여 선박의 주요 치수 최적화를 수행하였다. 설계 탐색 기법은 최적화 프로그램 HEEDS의 SHERPA 알고리즘을 사용하였다. 유동 해석은 상용 CFD 코드인 STAR-CCM+를 사용하였고, 주요 치수 변환은 전처리 과정에서 JAVA Script와 Python을 사용하여 선박의 치수가 자동으로 변환되도록 설정하였다. 대상 선박은 소형 쌍동선형으로 주요 치수 최적화는 한쪽 선형의 길이, 폭, 흘수 그리고 단동선형 간의 간격에 대하여 수행되었다. 최적화 알고리즘에 사용된 목적함수는 총저항이며, 내부 의장 시스템의 크기 등을 고려한 배수 체적의 범위를 제한조건으로 선정하였다. 그 결과 최적 선형의 주요 치수는 기존 선형 대비 ±5% 내에서 변화가 있었고 총저항은 약 11% 개선된 결과를 보였다. 본 연구를 통해 선박의 형상을 직접 변경하지 않더라도 주요 치수 최적화를 통해 선박의 저항 성능이 향상됨을 확인하였고, 다양한 선박의 주요 치수 최적화를 통한 성능 향상에 활용이 될 것으로 기대한다.

Evaluation of the Seakeeping Performance Indices for Enhancing Crew Safety and Workability in Small Fishing Vessels

박동우,이기동,서장훈 한국해양공학회 2024 한국해양공학회지 Vol.38 No.6

This study evaluated the applicability of the seakeeping performance indices for assessing the safety and crew workability of small fishing vessels, considering the high incidence of accidents in this type of vessel and the limited research on the impact of vessel motion on crew safety. Hydrodynamic analyses of 16 fishing vessels were conducted and the responses of roll, pitch, MII (Motion induced interruption), and MSI (Motion sickness incidence) were derived under various environmental conditions. A three-dimensional panel method based on potential flow theory was used to assess the motion responses of the vessels. Viscous roll damping coefficients were derived from computational fluid dynamics simulations for three representative vessels and applied to the remaining vessels. The results suggested that the magnitude of the seakeeping performance indices varied according to the vessel dimensions and main particulars. In particular, MII exceeded the established criteria for most vessels except in the lowest environmental condition, highlighting the need for criteria specific to small fishing vessels. The study also examined the influence of the forward speed on the indices and found that roll and pitch responses increase with the speed while MSI decreases marginally. Overall, these findings may help enhance the safety of vessels and crew members in small fishing vessels.

일반상선의 선수 개구부가 저항 및 자항성능에 미치는 영향

박동우,Park, Dong-Woo 해양환경안전학회 2014 해양환경안전학회지 Vol.20 No.1

LNG-RV has the additional equipments that enable to re-gastify liquefied LNG in LNG carrier. This vessel has Submerged Turret Loading(STL) system which transports gas through submarine terminal. When LNG-RV is operating at sea, the opening condition is formed by detaching STL equipment from a vessel. The primary objective of the current work is to estimate accurate speed loss for the opening condition of the LNG-RV employing numerical calculations and model tests. In the model tests, resistance and self-propulsion tests are carried out for the bare-hull and the opening condition without STL. In addition to these, flow visualization utilizing tuft is used to make the flow patterns visible, in order to get a qualitative or quantitative information for inner part in case of detaching the STL.

An HPSG Approach to English Comparative Inversion

박동우 서울대학교 언어교육원 2017 語學硏究 Vol.53 No.2

It has been analyzed that the word order of English comparative inversion is analogous to that of other subject-auxiliary inversion constructions, in that only a finite auxiliary verb (i.e., the highest auxiliary) can be followed by the subject. However, English comparative inversion must be distinguished from other inversion constructions, since the subject can be located between a cluster of auxiliary verbs and the non-auxiliary phrase in English comparative inversion. Existing analyses of subject-auxiliary inversion cannot account for this special kind of inversion. This paper proposes a new phrase type, called inv-focus-cl, for English comparative inversion within the framework of constructionbased Head-driven Phrase Structure Grammar (HPSG). Additionally, I suggest that constraints on properties of lexemes participating in the inv-focus-cl are governed by the construction-based approach, while the word order of English comparative inversion is determined by independent rules that determine the word order of lexical items, as the word order domain approach suggests.

Correlation between terahertz characteristics and defect states in LTG-InGaAs

박동우,김준오,이상준,김창수,이대수,노삼규,강철,기철식,김진수 한국진공학회 2010 한국진공학회 학술발표회초록집 Vol.39 No.-