• 한국항해항만학회지
• /
• 제35권7호
• /
• pp.575-580
• /
• 2011

It is important to understand the trajectory of structure in launching process because of the short time of launching process may result in unexpected accidents or damage to structures. The high risk of structural failure is not avoidable without the fully comprehension of changing forces in launching procedure. The commercial software can evaluate the motion of launching event in calm water condition but there is the limitation of research application because of the programmed commercial software. The launching process of the spar hull is suggested with stage concept that is divided into 10 stages in time domain. A force equilibrium diagram is derived for each stage where the changes of force vector and motion characteristics take place. In particular, the effects of changes in buoyancy and drag force due to the progressive submergence of the spar hull are taken into account by means of a touch length concept. The results contained in this paper provide the valuable information of the trajectory motion evaluation with suggested methods in spar launching process with sliding barge. Furthermore, the presented stage concept and touch length concept will provide basic knowledge for understanding launching process and help to develop further research area for launching analysis.

• 시스템엔지니어링학술지
• /
• 제4권2호
• /
• pp.45-54
• /
• 2008

This paper describes an operational concept of the network based future airborne force power using a systems engineering approach. The battlefield is changing to new system of systems that command and control by the network based BM/C4ISR. Also, it is composed of various sensors and shooters in an single theater. Future threats may be characterized as unmanned moving bodies that the strategic effect is great such as UAVs, cruise missile and tactical ballistic missiles. New threats such as low altitude stealth cruise missile may also appear. The implementation of future airborne force power network systems against these future threats is required to complex and integrated approach based on systems engineering. This work developed the operational concepts of the future airborne network system, and then derived the requirements for performing missions effectively. In addition, the scheme of future airborne force power network systems is presented.

• 대한기계학회논문집A
• /
• 제25권9호
• /
• pp.1334-1340
• /
• 2001

In this paper, the experimental modeling of the force between permanent magnet and iron-core solenoid is suggested for more accurate control of 3 D.O.F. motor using the electromagnetic force. In the case of iron-core solenoid, the general equation of solenoid cant be used simply because of its nonlinearity. Therefore, the magnetic flux density is estimated through the concept of equivalent permanent magnet. The force distribution between permanent magnet and iron-core solenoid is more dependent on the magnetization of iron core caused by the permanent magnet than any other parameters. Therefore, the equation of the force estimation between these magnetic systems can be modeled by the experimental function of the magnetization of iron core. Especially, if the distance between iron-core solenoid and permanent magnet is far enough, the force equation through experiment can be expressed from only the current of coil and the distance between iron-core solenoid and permanent magnet. It means that Coulombs law can be used for magnetic systems and it is validated through the experiment. Therefore, force calibration is performed by the concept of Coulombs law.

• 한국전산구조공학회논문집
• /
• 제24권5호
• /
• pp.481-489
• /
• 2011

본 논문에서는 트러스 구조 해석에 있어서 기존의 하중법을 특이값 분해로 정식화 한 새로운 하중법을 제안하였다. 하중법은 유한요소법을 이용한 트러스 구조 해석법과 달리 접근 방법이 쉬우며 어려운 구조적 개념이 필요하지 않아 일반적인 트러스 구조 해석에서 주로 사용된다. 또한 트러스 및 핀-조인트 골조와 같은 골조 시스템의 구조 해석에도 적용할 수 있어 매우 효과적인 방법이다. 하지만 하중법은 많은 수식을 통해 구조 해석을 수행하여야 하므로 이로 인해 수치상의 오류가 발생할 수 있다. 따라서 본 연구에서는 이러한 문제점을 보완하기 위하여 기존의 하중법에서 사용하던 수식을 특이값 분해로 정식화 한 새로운 하중법을 제안하였다. 이 방법을 사용하여 트러스 구조물을 해석할 경우 기존의 하중법의 기본개념을 그대로 이용하면서도 복잡한 수식을 사용하지 않고 해석을 수행할 수 있으므로 매우 효율적인 방법이다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
• /
• pp.1708-1713
• /
• 1997

In teleoperation of a manipulator, kinesthetic feedback can take an essential role in the sense that it provides an operator with more realistic information. In this paper, in order to implement the concept of kinesthetic feedback, force mapping algorithms based on screw theory have been presented. In the development of such algorithms, the virtual environment has been modeled usign a spring and dampers, and the forces caused by hitting the joint limits of a conrtolled manipulator were considered. Finally, some experimental results of force mapping algorithm have been presented.

• 한국과학교육학회지
• /
• 제28권6호
• /
• pp.579-591
• /
• 2008

학생의 선개념을 상황과 함께 파악하려는 시도로서 최근에 전형적 인식 상황(TPS)에 대한 연구와 결정적 예에 대한 연구가 수행되었다. TPS는 개념에 대해 생각할 때 가장 먼저 떠오르는 상황이며, 결정적 예는 학습에 가장 큰 도움이 된 예시 상황이다. 우리는 전형적 인식 상황과 결정적 예를 함께 파악함으로써 학생의 개념 이해 과정에서 상황이 어떻게 관련되는 지를 살펴볼 수 있다. 본 연구에서는 설문 조사와 면담을 통해 $9{\sim}11$학년 학생이 '힘'과 '역학적 에너지 전환'에 대해 가지고 있는 전형적 인식 상황과 결정적 예의 특징을 분석하고 그 관련성을 알아보고자 하였다. 연구 결과, 학생들의 전형적 인식 상황과 결정적 예는 개념에 따라 다른 특징을 보였다. 일상 생활과 깊이 관련되어 있는 힘의 경우에는 학생들이 다양한 상황을 TPS와 결정적 예로 가지고 있었다. 반면, 역학적 에너지 전환에 대해서는 공이 떨어지는 것과 같은 몇몇 상황을 전형적 인식 상황과 결정적 예로 가지고 있는 학생들이 많았다. 또, 학생들은 교과서와 일상생활에서 자주 접하는 상황이나 쉽게 이해할 수 있는 상황을 TPS나 결정적 예로 생각하는 경향이 있었다. 이상의 논의에서 TPS에서 시작하여 개념을 도입하고 이후 개념의 속성이 잘 드러나는 결정적 예를 제시하여 학습이 일어날 수 있도록 하는 것이 효과적인 과학 개념의 교수-학습 방안으로 보인다.

• 시스템엔지니어링학술지
• /
• 제11권2호
• /
• pp.61-73
• /
• 2015

The early-phase naval ship design demands requirements synthesis rather than design synthesis, which conducts engineering design for several domains on a detailed level. Requirements synthesis focuses on creating a balanced set of required operational capabilities satisfying user's needs and concept of operations. Requirements are evolved from capability based languages to function based language by statistical exploration and engineering design which are derived in the following order: concept alternative, concept baseline, initial baseline and functional baseline. The early-phase naval ship design process can be divided into three passes: concept definition, concept exploration and concept development. Main activities and outcomes in each pass are shortly presented. Concept definition is the first important step that produces a concept baseline through extensive design space exploration promptly. Design space exploration applies a statistical approach to explore design trends of existing ships and produce feasible design range corresponding to concept alternative. It further helps naval systems engineers and operational researchers by inducing useful responses to user and stakeholders' questions at a sufficient degree of confidence and success in the very early ship design. The focus of this paper is on the flow of design space exploration, and its application to a high-speed patrol craft. The views expressed in this paper are those of the authors, and do not reflect the official policy or rule of the Navy.

• 대한기계학회논문집A
• /
• 제28권9호
• /
• pp.1344-1351
• /
• 2004

This study develops a haptic display model which is an indispensable for the force generation in the virtual environment. In developing the haptic display model, a Proxy concept and a Karnopp friction model are utilized to generate the reaction force and the friction force. Also this study develops a 2 D.O.F. remote wiping system. This system is composed of a 2 D.O.F. master manipulator, a force sensor equipped 2 D.O.F. slave manipulator and a real time controller. With the developed remote wiping system, this study identifies the friction characteristic of the aluminum, acryl and rubber plate. The results are used as the dynamic friction coefficient of the haptic display model. This study shows the efficiency of the developed haptic display model by the comparison between the friction characteristic of the haptic display with the developed haptic display model and the friction characteristic of the real aluminum, acryl and rubber plate.

• Journal of Mechanical Science and Technology
• /
• 제18권1호
• /
• pp.132-144
• /
• 2004

This paper presents a new method driving multiple robots to their goal position without collision. To consider the movement of the robots in a work area, we adopt the concept of avoidability measure. The avoidability measure figures the degree of how easily a robot can avoid other robots considering the velocity of the robots. To implement the concept to avoid collision among multiple robots, relative distance between the robots is proposed. The relative distance is a virtual distance between robots indicating the threat of collision between the robots. Based on the relative distance, the method calculates repulsive force against a robot from the other robots. Also, attractive force toward the goal position is calculated in terms of the relative distance. These repulsive force and attractive force are added to form the driving force for robot motion. The proposed method is simulated for several cases. The results show that the proposed method steers robots to open space anticipating the approach of other robots. In contrast, since the usual potential field method initiates avoidance motion later than the proposed method, it sometimes fails preventing collision or causes hasty motion to avoid other robots. The proposed method works as a local collision-free motion coordination method in conjunction with higher level of task planning and path planning method for multiple robots to do a collaborative job.

• 한국국방경영분석학회지
• /
• 제27권2호
• /
• pp.88-109
• /
• 2001

Defense minister of the ROK, Kim Bong-sin suggested that the ROK′s military build-up policy will change from "scenario-based" to "capability-based". Entering the 1990s the ROK′s military build-up policy met difficulties to accomplish its goal, modernizing and strengthening of its force structure and weapon systems because of limited budget. The concept of capability-based military build-up could commit a fault in estimating total amount of defense resources required for force planing. This is because that the total amount of defense resources related to force plan for the 15 years is fixed to embody military strategy. The concept of capability-based military build-up plays a role as a constraint in choosing a military strategy. This has no connection with military build-up. Therefore the resources of mid-term military build-up program and scale of annual defense budget could be affected by the situations of its national economy. In this respect, the scale of annual defense budget and resources could be changed in accordance with national economic condition, however, the total amount of resources required to build-up military force for 15 years, namely resources of military force planing requirement for 15 years, is given already for the accomplishment of military strategy. The purpose of this study is to seek a direction of the ROK′s military build-up policy in a viewpoint of capability-based military build-up.