• 한국신뢰성학회지:신뢰성응용연구
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• 제8권2호
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• pp.87-100
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• 2008

The rubber fender is used to absorb the berthing energy that is produced when a ship is near a port, and it prevents collision between the ship and port. If the rubber fender becomes defective, the berthing energy cannot be absorbed when it is near the port, and damage can result from collisions due to the hardening process. In this research, when the rubber fender is heated, collisions can cause cracks and other damage. It is also confirmed from the research the lifetime distribution of the rubber fender. The researcher has predicted using different variables and elongation that a rubber fender has an 11year lifespan at $20^{\circ}C$.

• 수산해양교육연구
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• 제29권1호
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• pp.201-208
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• 2017

The major cause of the marine accidents is the collision with a moving object such as ship as well as the fixed object such as breakwater. Therefore, the most effective way to reduce the maritime ship accidents is the prevention of collision. In order to decrease the collision, it is principle that the navigation officer promptly judges the dangerous condition and makes the quick response. The ship does not allow any object or other ships approaching its surrounded area called ship area so that it prevents the collision. Generally, the ship which has high speed or poor maneuvering capability shall be managed from the distance so that the other ship does not invade its ship domains(watching distance, blocking distance). Accordingly, this study sets the navigational risk assessment model by applying ship dynamic domain and collision judgement method considered ship length, speed and navigational capability. It also reviewed the validity of the model and evaluated the perilous water way (Maenggol Channel) and a curved route near Maenggol Channel. As a result, in case of a ship with 100m in length passing Maenggol Channel, it represented "warning" level before 1.5nm to the entry, "dangerous"level 0.75nm before to it and "very dangerous" level 0.5nm before to it and then "dangerous"level again up to the entry. Applying to the curved route also showed the same results as the Narrow Channel or Maenggol Channel. This analysis highly matched with the actual navigation results. In the future, this model will be useful for coastal navigation safety chart development and safety evaluation for route or port development. It also allows to evaluate the dangerous route or the best route by applying the result into ECDIS so that it will finally help to reduce the marine accidents. Eventually the model will be effective for the marine traffic simulation evaluation forced by Maritime Traffic Safety Act.

• 해양환경안전학회지
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• 제25권1호
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• pp.1-8
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• 2019

2017년 12월 인천의 영흥도에서 발생한 급유선과 낚시어선의 충돌사고를 비롯하여 소형 어선의 충돌 사고가 잇따라 발생하고 있다. 해양수산부에서 이러한 소형 어선의 해양사고를 예방하기 위하여 5톤 미만의 어선원에 대한 교육 훈련 규정 마련 등 교육 강화 및 근로환경 개선 등 선박종사자의 안전역량 제고를 위해 노력하고 있으나, 여전히 소형 선박은 해양사고에 매우 취약한 실정이다. 본 연구에서는 소형선박의 충돌 사고를 예방하기 위하여 새로운 통신 기법인 차량용 무선통신(WAVE 통신)을 활용한 소형 선박을 위한 충돌 예방 알고리즘을 구축하고자 하였다. 충돌 예방 알고리즘은 DCPA/TCPA를 기반으로 구성되었으며, DCPA/TCPA의 기준 설정을 위하여 선행 연구 분석, 시뮬레이션 실험 및 설문조사를 실시하였다. 그 결과 DCPA $8(L_a+L_b)$, TCPA 2.5min의 기준을 적용하였다. 각각 다른 조우 상황의 3가지 사고 사례를 선별한 후 구성된 알고리즘을 적용하여 어느 시기에 경보가 발생하는지 확인하였다. 추후에 실선 적용을 통하여 문제점을 식별하고 알고리즘을 고도화한다면 소형 선박의 운항자가 충돌 상황을 사전에 인지하는데 정보를 제공할 수 있다.

• 정보저장시스템학회논문집
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• 제3권1호
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• pp.1-4
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• 2007

A high density optical data storage device has been required for many years. In the field of the optical data storage, a near-field recording (NFR) technology is considered as a next generation one for achieving the high data density. Due to an evanescent wave effect occurred under 100nm distance which is the excessively small distance between the SIL and the disc, the most significant and difficult problem in this technology is to maintain a gap between a solid immersion lens (SIL) and a disc. Also, maintaining the gap under at least 50nm is required in the NFR gap servo system to use the evanescent wave effect efficiently. There are some institutes that have shown the novel gap servo control. In general, they use a mode switching servo method which consists of approach, hand-over and gap control mode. However there is a critical problem such as an overshoot at the tuning point from the approach mode to the hand-over mode, which may cause a collision between the SIL and the disc. In this paper, we show our NFR system and an improved gap servo system using an exponential function as the approach mode which can reduce the overshoot.

• 해양환경안전학회지
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• 제26권6호
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• pp.594-600
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• 2020

선박과 물체의 충돌위험을 파악하는 것은 항해안전에 중요하다. 본 연구의 목적은 선박이 방파제 사이를 통과할 때 선박 도메인이 방파제에 의해서 침범당하는 현상을 분석하는 것이다. 연구방법은 먼저, 방파제가 주어진 조건으로 설계된 선박 도메인을 침범하는 영역을 평가하기 위한 방법을 제안하였다. 그런 후, 부산항 방파제 부근을 항해하는 선박들의 AIS(Automatic Identification System)로부터 실험 데이터를 획득하고 처리하여 방파제 사이에서 형성될 수 있는 선박 도메인을 구축하였다. 이 때 선박 도메인은 Fujii의 Domain을 이용해 구축하였다. 마지막으로, 구축한 선박 도메인이 방파제에 의해서 침범당하는 현상을 분석하였다. 실험결과, 방파제에 의해서 침범당하는 선박 도메인이 확인되었다.

• 제어로봇시스템학회논문지
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• 제21권9호
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• pp.888-897
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• 2015

A flight capability to take a terrain following flight near the ground is required to reduce the probability that a fighter aircraft can be detected by foe's radar fence in the battlefield. The success rate for mission flight has increased by adopting TFS (Terrain Following System) to enable the modern advanced fighter to fly safely near the ground at the low altitude. This system has applied to the state-of-the-art fighter and bomber, such as B-1, F-111, F-16 E/F and F-15, since the research begins from 1960's. In this paper, the terrain following system and GCAS (Ground Collision Avoidance System) was developed, based on a digital database with UTAS's TERPRROM (TERrain PROfile Matching) equipment. This system calculates the relative location of the aircraft in the terrain database by using the aircraft status information provided by the radar altimeter and the INS (Inertial Navigation System), based on the digital terrain database loaded previously in the DTC (Data Transfer Cartridge), and figures out terrain features around. And, the system is a manual terrain following system which makes a steering command cue refer to flight path marker, on the HUD (Head Up Display), for vertical acceleration essential for terrain following flight and enables a pilot to follow it. The cue is based on the recognized terrain features and TCH (Target Clearance Height) set by a pilot in advance. The developed terrain following system was verified in the real-time pilot evaluation in FA-50 HQS (Handling Quality Simulator) environment.

• 한국해양공학회지
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• 제30권3호
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• pp.208-213
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• 2016

This paper proposes a potential field-based guidance law for docking a USV (unmanned surface vehicle). In most cases, a USV without side thrusters is an under-actuated system. Thus, there are undockable regions near docking stations where a USV cannot dock to a docking station without causing a collision or backward motion. This paper suggest a guidance law that prevents a USV from enter such a region by decreasing the lateral error to the docking station at the initial stage of the docking process. A Monte-carlo simulation was performed to validate the performance of the proposed method. The proposed method was compared to conventional guidance laws such as pure pursuit guidance and pure/lead pursuit guidance. As a result, the collision angle and lateral distance error of proposed method tended to have lower values compared to conventional methods.

• 한국대기환경학회지
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• 제27권6호
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• pp.681-691
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• 2011

The size distributions of smoke particles from fire are prerequisite for the studies on fire detection and adverse health effects. Above the flame of the fire, coagulation dominates and the smoke particles grow from 1 to 50 nm up to 100 to 3,000 nm, sizes ranging from the free-molecular regime to the continuum regime. The characteristics of the agglomeration of the smoke particles are well known, independently for each of the free-molecular and continuum regimes. However, there are not many systematic studies in the entire regime by the complexity of the mechanisms. The purpose of this work is to find the characteristics of the development of the size distribution of smoke particles by agglomeration in the entire size range covering the free-molecular regime, via transition regime, to the near-continuum and continuum regime for each variation of parameters such as fractal dimension, primary particle size and dimensionless coagulation time. In this work, the dynamic equation for the discrete-size spectrum of the particles was solved using a nodal method based on the modification of a sectional method. In the calculation, the collision frequency function for the entire regime, which is derived by using the concept of collision volume and general enhancement function, was applied. The self-preserving size distribution for the entire regime is compared with the ones for the free-molecular or continuum regimes for each variation of the parameters.

• 한국항해항만학회지
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• 제33권9호
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• pp.623-628
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• 2009

The objective of this paper is to make clear the difference of maneuvering characteristics of a VLCC in standstill from those of her in running. The authors made mathematic models to calculate maneuvering motions of a VLCC in standstill using various ahead engine with full rudder angle and calculated their motions in each case and compared the calculated values with those of the same vessel running in sea trial tests. The difference of motions between them is great. For example, a VLCC in standstill can achieve a great alteration of heading over 90 degrees within the distance of 0.2L advance while she advances 3.0L for 90 degrees turning in full running sea trial turning test. Therefore whenever a VLCC in standstill meets a vessel approaching in collision course situation in near distance, it is better and recommendable that she should use her ahead engine with full rudder to avoid collision. So "maneuvering trial tests in standstill conditions" should be added to the content of sea trial tests when a newly built VLCC commence to take sea trials, that has not been included until now.

• 한국항해항만학회지
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• 제33권7호
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• pp.463-467
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• 2009

In near future, more congested and dangerous marine traffic environment due to the rapid marine traffics increase and ship handling difficulty by enlargement of ship size is predicted. In this paper, an navigation supporting system proposal made to enhance the safe navigation by providing the collision avoidance informations to the navigator via marine traffic environment assessment. Proposed navigation supporting system displays results of marine traffic environment assessment, degree of the dangers and gives reason of danger which is enhance situational awareness of navigator. For this purpose, results of marine traffic environment assessment which is obtained via real time assessment sent to the designated server and through the connection with navigation supporting system navigator being enable to see all those informations on the computer screen Navigator would utilize those information to make a decision in the difficult waterways and thus safe navigation could be enhanced.