龜裂成長을 考慮한 J-抵抗 曲線의 決定

정태권,이상호 조선대학교 동력자원연구소 1988 動力資源硏究所誌 Vol.10 No.2

The fracture toughness of SCM4 was investigation for various crack ratios using unloding compliance method. In assumption of stable crack growth, crack growth amount(Δa) was obtained from measurement of compliance during a sequence of loading and unloading and J_IC was determined from J-Δa curve and blunting line. The J-integral computed at the initiation point of the slow stable crack growth was almost constant within the range of crack ratios tested in this study. The fracture toughness value thus obtained was 32.46K_gf/㎜. A reasonable J-resistance curve determination procedure is suggested by correcting the amount of overestimation in J-value which effect becomes significant when crack grows. J-value estimation according to this procedure is compared with those obtained from the other conventional methods proposed by Rice and Merkle & Corten. From the results of experiment the J-R curve of material seems to be independent on crack length.

폐쇄형 원심펌프의 임펠러유동해석

김태한,권형정 동의공업대학 2001 論文集 Vol.27 No.1

Compute simulations for closed type centrifugal pump is carried out using the commercial code CFX Tascflow. Computed results, which are pressure, velocity between impeller and other impeller, required power and performance etc, was compared with actual experimental data. We found that there are hard loads due to velocity and pressure at in/outlet impeller, and pump head is within 10% error limit when volute head loss is considered to 20% loss of total head. Accordingly it is possible to get optimal impeller shape through the iteration improvement works. But, as this study was done for only impeller in order to confirm the validity of Tascflow program, computation including the volute is required for actual comparison. For this, volute data treatment process for grid generation remains with future projects.

경주지역 여고생의 초경과 체성장간의 관계

김준섭,권오구,박진석,오종수,박정현,박제식,안세한,이용환,서정호,신태섭,최영배,김덕수,이관,박수경 東國大學校醫學硏究所 2002 東國醫學 Vol.9 No.1

본 연구는 경주지역 1개 고등학교 3학년 여고생을 대상으로 초경 시작 전인 초등학교 4학년부터 고등학교 2학년까지의 키, 몸무게, 가슴둘레 수치와 초경 연령을 파악하여 여성의 초경이 빠를수록 체성장 속도의 변화가 있을 것이라는 가설을 기초로 두 요인간의 관련성을 파악하고자 시행되었다. 경주시 1개 여자고등학교 3학년생 총 317명에 대해 ㅊ경 나이, 초경시 심리 상태, 초경이 시작되었을 때의 상담 여부와 상담하였던 사람, 부모 신장과 초경전후의 식사 규칙성, 다이어트 경험, 수면시간, 스트레스, 음주/흡연 여부, 질병력 등에 대한 설문 조사를 시행하였고, 초등학교 4학년부터 고등학교 2학년까지의 키, 몸무게, 가슴둘레에 대한 정보는 건강기록부에서 확보하였다. 상기 대상자 중 건강기록부가 분실된 39명, 초경나이에 대해 응답하지 않았던 29명 및 결석 등으로 조사를 하지 못하였던 42명을 제외한 조사 대상자는 206명으로 선정하였다. 대상자들의 초경연령 평균값(Mean±SD)은 13.0±1.11이었고, 초등학교 4학년부터 고등학교 2학년까지의 초경 이후 신장 성장률은 감소하였으며, 초경연령이 빠른 군이 초등학교 때는 신장에 있어서 우위를 차지하나 고등학교에 오면서 신장은 비슷한 수준이 되었다. 초경후 1-2년 사이에 체중과 흉위의 증가율은 감소하였고, 초경연령이 빠른 군이 초등학교와 고등학교 사이에 체중과 흉위에서 모두 우위를 차지하였다. 본 연구의 결과는, 흔히 이차 성징의 시작 시점 혹은 사춘기의 시작 시점으로 보고있는 초경 연령이 청소년기의 성장과 밀접한 관련성이 있고, 특히 체중과 흉위의 성장 속도와 밀접한 관련성이 있음을 시사한다. To understand the onset of menarche in relation to changes in physical growth that take place during female adolescence, especially the changes in height and weight velocity. The 207 senior in one women high school of Kyongju were investigated in April 3 to 8, 2001. We collected the information, relation in the age at menarche, height & weight of parents, regularity of eating, and obesity diet, duration of sleeping, sickness & stress near age at menarche, by self-recording. The status of height, weight & chest circumference between the 4th grade of primary school and the junior of high school was collected by individual Health Record. The results were followed; The average age at menarche was 12.95±1.11 years old and the most frequent age of menarche is 13 years. After menarche, the velocity of height, weight and chest circumference were decreased. The most rapid group of menarche hold dominant position in height during elementary school. As time passed, they dont hold dominant position in height. The most rapid group of menarche get an advantage in the weight and the girth of chest after elementary school. The height of subjects is directly proportional to the height of their parents. These results suggest that the starting age at menestuation can be closely associated with physical growth and development.

An Algorithmic Study on Free-gyro Positioning System( I ) - Measuring Nadir Angle by using the Motion Rate of a Spin Axis -

Jeong, Tae-Gweon,Park, Sok-Chu Korean Institute of Navigation and Port Research 2007 한국항해항만학회지 Vol.31 No.9

The authors aim to establish the theory necessary for developing free gyro positioning system and focus on measuring the nadir angle by using the motion rate of a free gyro. The azimuth of a gyro vector from the North can be given by using the property of the free gyro. The motion rate of the spin axis in the gyro frame is transformed into the platform frame and again into the NED (north-east-down) navigation frame. The nadir angle of a gyro vector is obtained by using the North components of the motion rate of the spin axis in the NED frame. The component has to be transformed into the horizontal component of the gyro by using the azimuth of the gyro vector and then has to be integrated over the sampling interval.

Development of Collision Avoidance Expert System by Using CLIPS and Visual C++

Tae-Gweon JEONG,Chao CHEN 한국항해항만학회 2007 한국항해항만학회지 Vol.31 No.2

Evaluation of collision risk plays a key role in developing the expert system of navigation and collision avoidance. This paper presents a new collision risk model formula that is one modification model on the basis of one approach to the evaluation of collision risk using sech function produced in earlier studies. And as a tool of the evaluation field of ship collision, this paper applied the new model in appraising the collision risk and represented how to decide the safe range of own ship’s action. Moreover this paper also analyzed theoretically how to determine the coefficients as described in the new modification model, and suggested the appropriate values as applicable.

An Algorithmic Study on Free-gyro Positioning System( I ) : Measuring Nadir Angle by using the Motion Rate of a Spin Axis

Tae-Gweon Jeong,Sok-Chu Park 한국항해항만학회 2007 한국항해항만학회지 Vol.31 No.9

The authors aim to establish the theory necessary for developing free gyro positioning system and focus on measuring the nadir angle by using the motion rate of a free gyro. The azimuth of a gyro uector from the North can be given by using the property of the free gyro. The motion rate of the spin axis in the gyro frame is transformed into the platform frame and again into the NED (north-east-down) navigation frame. The nadir angle of a gyro vector is obtained by using the North components of the motion rate of the spin axis in the NED frame. The component has to be transformed into the horizontal component of the gyro by using the azimuth of the gyro vector and then has to be integrated over the sampling interval.

Theoretical Approach of Development of Tracking Module for ARPA system on Board Warships

Tae-Gweon Jeong,Bao-Feng Pan,Anne Wanjiru Njonjo 한국항해항만학회 2015 한국항해항만학회 학술대회논문집 Vol.2015 No.추계

The maritime industry is expanding at an alarming rate and as such there is a perpetual need to improve situation awareness in the maritime environment using new and emerging technology. Tracking is one of the numerous ways of enhancing situation awareness by providing information that may be useful to the operator. The tracking system described herein comprises determining existing states of own ship, state prediction and state compensation caused by random noise. The purpose of this paper is to analyze the process of tracking and develop a tracking algorithm by using α-β-γ tracking filter under a random noise or irregular motion for use in a warship. The algorithm involves initializing the input parameters of position, velocity and course. The actual positions are then computed for each time interval. In addition, a weighted difference of the observed and predicted position at the nth observation is added to the predicted position to obtain the smoothed position. This estimation is subsequently employed to determine the predicted position at (n+1). The smoothed values, predicted values and the observed values are used to compute the twice distance root mean square (2drms) error as a measure of accuracy of the tracking module.

A Study on Development of LCD monitor-Based Pilots' Ship-Handling Simulator

Jeong, Tae-Gweon,Chen, Chao,Lee, Shin-Geol,Lee, Jeong-Jin,Huh, Yong-Bum Korean Institute of Navigation and Port Research 2012 한국항해항만학회지 Vol.36 No.9

This paper is to introduce the development of a LCD monitor-based pilots' ship handling simulator installed in the office of Korea Maritime Pilots Association. This simulator is composed of hardware which includes working server array, operation PC, monitor array, rudder, thruster and telegraph peripheral devices, and software which includes ship mathematical model software, ship conning software, image supporting software and so on. In this simulator, MMG mathematical model is used to create thirteen(13) ship models, which are based on sea trial data & pilots' opinion. According to requirements of pilots, virtual scenes of different port areas are built, and some required additional functions are also developed. By using this simulator, pilots can fulfill all kinds of training exercises, design of channel approaching ports, traffic safety analysis, prevention of accident research and other tasks, so as to grasp the characteristics of different ships, and accumulate experience for piloting.

Experimental Results of Ship-to-ship Stabilized Mooring System for Mobile Harbor

Jeong, Tae-Gweon,Lee, Yun-Sok,Chen, Chao,Kim, Se-Won Korean Institute of Navigation and Port Research 2010 한국항해항만학회지 Vol.34 No.4

A new concept of ocean transport system, called mobile harbor, was introduced as a feasibility study in Korea in 2009. Target of the mobile harbor is a short distance transport of containers with or without cargo handling cranes. Although the mobile harbor project has a lot of topics to deal with, this paper is to focus on only ship-to-ship stabilized mooring, which plays a key role in cargo handling. The ship-to-ship stabilized mooring system was developed and installed on board a barge of LOA 32m and breadth 12m. The dockside tests as sea test were carried out so as to ascertain whether the systems can work well to control the barge’s motion. The results of dockside test showed that the heave motion of the barge's motion can be reduced by more than 45%.

A Study on Minimum Number of Ship-handling Simulation Required for Evaluating Vessel’s Proximity Measure

Tae-Gweon JEONG,Bao-Feng PAN 한국항해항만학회 2014 한국항해항만학회지 Vol.38 No.6

The Korean government has introduced and enforced maritime traffic safety assessment to secure traffic safety since 2010. The maritime traffic safety assessment is needed by law to design a new port or modify an existing one. According to Korea Maritime Safety Act, in the assessment the propriety of marine traffic system consists of the safety of channel transit and berthing/unberthing maneuver, safety of mooring, and safety of marine traffic flow. The safety of channel transit and berthing/unberthing maneuver can be evaluated only by ship-handling simulation. The ship-handling simulation is carried out by sea pilots working with the port concerned. The vessel’s proximity measure is an important factor to evaluate traffic safety. The proximity measure is composed of vessel’s closest distance to channel boundary and probability of grounding/collision. What is more, the probability of grounding becomes important. According to central limit theorem, a sample has a normal distribution on condition that its size is more than 30. However, more than 30 simulation runs bring about the increase of assessment period and difficulty of employing sea pilots. Therefore this paper is to find out minimum sample size for evaluating vessel’s proximity. First sample sets of size of 3, 5, 7, 9 etc. are selected randomly on the basis of normal distribution. And then KS test for goodness of fit and t-test for confidence interval are applied to each sample set. Finally this paper decides the minimum sample size. As a result this paper suggests the minimum sample size of 5, that is, the simulation of more than five times.