• 한국시스템다이내믹스연구
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• 제17권2호
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• pp.5-32
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• 2016

Purpose of this paper is to review series of Limits to Growth studies from its original Rome Club Report published in 1972 to the most recent one in 2012 by Jorgen Randers and finds its implications on concept and strategy of sustainable development. For this purpose first, this paper reviewed series of Limits to Growth studies in details with focus on scenarios used in simulation of world model. Second, response to the original Limit to Growth was reviewed and to see validity of its scenario based simulations, simulated results of interest variables and actual historical data up to the year 2010 was compared. Third, structure and key arguments in both studies, Limit to Growth studies and Our Common Future was explained and compared. Finally, implications of the Limit to Growth studies on concept and strategy for sustainable development was discussed. Based on the comparison, this paper argued that even if the term sustainable development was not used in the Limit to Growth at all, concept and strategies for sustainable development implied in the Limit to Growth are more clear and specific than those of Our Common Future. Since Limit to Growth studies were simulation based ones that produce detailed behaviors on interest variables, it clarifies more clearly the abstract concept of sustainable development and thus, provides specific guidelines for the direction of sustainable policy which has been suffering long from vagueness of concept of sustainable development.

• 대한수학교육학회지:수학교육학연구
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• 제12권4호
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• pp.557-579
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• 2002

The purpose of this study is to find out the problems which are caused when the limit concept of sequences is learned through an intuitive definition and to suggest a way of solving those problems. Students in Korea study the limit concept of sequences through an intuitive definition. They fail to apply the intuitive definition properly to the problems and they are apt to have misconception even though the Intuitive definition is applied properly. To solve these problems, this study examined the develop- mental process of the limit concept of sequences from the Intuitive definition to the formal definition, and looked into the way of students' internalization of the process through a field study. In this study, the levels of the limit concept of sequences possessed by the students at ZPD are as follows; level 0 : Students understand the limit concept of sequences through the intuitive definition. level 1 : Students understand the limit concept of sequences as 'The difference between $\alpha$$_{n}$ and $\alpha$ approaches 0' rather than 'The sequence approaches $\alpha$ infinitely.' level 2 : Students understand the limit concept of sequences through the formal definition. The levels of students' limit concept development were analysed by those criteria. Almost of the students who studied the limit concept of sequences through the intuitive defition stayed at level 0, whereas almost of the students who studied through the formal definition stayed at level 1. Through the study, I found that it was difficult for the students to develop the higher level of understanding for themselves but the teachers and peers could help the students to progress to the higher level. Students' learning ability was one of major factors that make the students progress to the higher level of understanding as the concept was developed hierarchically from Level 0 to Level 2. If you want to see your students get to the higher level of understanding in the limit concept, you need to facilitate them to fully develop understanding in lower levels through enough experiences so that they can be promoted to the highest level.

• 한국컴퓨터정보학회논문지
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• 제23권11호
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• pp.67-74
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• 2018

The verification for the design limit margin of the power device for the information communication and surveillance systems using HALT(Highly Accelerated Life Test) reliability test is described. The HALT reliability test performs with a step stress method which change condition until the marginal step in a design and development phase. The HALT test methods are the low temperature(cold) step stress test, the high temperature(hot) step stress test, the thermal shock cyclic stess test, and the high temperature destruct limit(hot DL) step stress test. The power device is checked the operating performance during the test. In this paper, the HALT was performed to find out the design limit margin of the power device.

• 산업기술연구
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• 제15권
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• pp.5-13
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• 1995

Natural gas, which is getting more important as a fuel, should be liquefied and shipped in a special tank. During transportation, a spill of liquefied natural gas(LNG) could occur by a collision or even an accident. As a result, violent explosion called the superheat-limit explosion(SLE) can take place in some cases, unexpectedly. Such explosion may result from the formation of a superheated liquid which has attained the superheat-limit temperature when hot(water) and cold(LNG) liquids come into contact. Natural gas mixtures can be considered as discrete light components plus continuous heavy fractions where several continuous distribution function can be adopted. This work is aiming at prediction of the superheat-limit explosion condition by suing continuous thermodynamics development of algorithm to predict.

• 한국공작기계학회논문집
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• 제11권6호
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• pp.31-37
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• 2002

This paper presents a new motion control strategy for singularity avoidance in 6 DOF articulated robot manipulators, based on a speed limiting algorithm for joint positions and velocities. For a given task, the robot is controlled so that the joints move with acceptable velocities and positions within the reachable range of each joint by considering the velocity limit. This paper aims at the development of a new efficient method to control robot motion near and at singularities. The proposed method has focused on generating the optimal joint trajectory for a Cartesian end-effector path within the speed limit of each joint by using the speed limit avoidance as well as the acceleration/deceleration scheme. The proposed method was verified using MATLAB-based simulations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1334-1338
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• 2005

A limit switch box is used for an indicator of a valve actuator. This device indicates an opening and closing of a valve or a throttle in the valve actuator. In a ship, equipments require safety and robustness because of a rough environment and a specific condition during a voyage. However, the limit switch box has been used in an indoor environment generally. This study developed a new limit switch box which can be used at an outdoor environment. This study designed the new limit switch box. The housing of the limit switch box was made by an aluminum die cast method with surface painting after anodizing or chromate coating. In order to evaluate the endurance of the housing, the endurance tests against salt water have been conducted. Experiment results showed that the proposed device provides a reliable performance against salt water.

• 해양환경안전학회지
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• 제21권3호
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• pp.274-282
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• 2015

This research is the result on calculating the logical speed limit through certain process which some elements must be considered on selecting the speed limit of harbour and waterway. The suggested speed limit select model on this research is processed from 1~6 steps by forming a professional group of experts. Each step has its information which 1st step(water division), 2nd step(selecting the model vessel and vessel applied with speed limit.), 3rd step(selecting the maximum and minimum speed range on each section), 4th step(evaluation on the safeness of traffic), 5th step(suggesting the appropriate speed limit), 6th step(execution and evaluation.). The appropriate speed limit was decided on consideration of the safety of maritime traffic on the range of the maximum speed and the minimum speed. This model was used to derive the appropriate speed limit on the harbour water and Busan harbour entrance waterway. As the result, the harbour water was calculated to be 6.9 knots, the appropriate speed limit of Busan entrance harbour was 9.3 knots. The present calculation of the speed limit on the approaching channel area is 10 knots, inner harbour area is 7 knots, which are similar to the result of the speed limit. This research is the first research on selecting the speed limit model and has its limits on finding the perfect speed limit result. More detailed standards on the safeness of traffic evaluation must be found and additional study is necessary on discriminating consideration of the elements. This research has its value which it provides instances of aboard cases on guidelines of selecting the speed limit.

• 한국정밀공학회지
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• 제29권12호
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• pp.1340-1345
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• 2012

Industrial products developed in recent years have focused on usability and stability. Especially, for the products used in daily life, steady efforts have been made to secure the safety. Among them, the products equipped with wheels such as strollers, shopping carts, and carriers can occur the safety accidents by unintended over speed at a ramp. Therefore, development of speed limit device is required to prevent such accidents. However, the existing speed limit devices are very expensive and have a complex drive principle, so it's generally difficult to apply them. In this study, a simple speed limit wheel is suggested which can replace the previous complex and inconvenient speed limit devices. The developed speed limit wheel can be simply applied to existing products by changing the wheels. In addition, it has an advantage to operate only by mechanical mechanism without power supply. Thus it can minimize the cost and waste of resources. For this purpose, the operating condition of the target products was analyzed, and trochoid gear mechanisms were selected for the speed limit. Based on this, finite element analysis was conducted to estimate the operating mechanism. After the prototype of the wheel was produced, the performance under various conditions was tested and has been improved.

• 대한기계학회논문집A
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• 제21권8호
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• pp.1218-1228
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• 1997

The move limit strategy is used to avoid the excessive approximation in the structural optimization. The size of move limit has been obtained by engineering experience. Recently, efforts based on analytic methods are performed by some researchers. These methods still have problems, such as prematurity or oscillation of the move limit size. The existing methods usually control the bound of design variables based on the magnitude. Thus, they can not properly handle the configuration variables based on the geometry in the configuration optimization. In this research, the size of move limit is calculated based on the accuracy of approximation. The method is coded and applied to the two-point reciprocal quadratic approximation method. The efficiency is evaluated through examples.

• 건설안전기술
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• 통권47호
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• pp.56-62
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• 2008

In order to apply the Limit Equilibrium Method generally used for the slope stability analysis to the vertical excavation walls reinforced by soil-nailing, in this study, the Limit Equilibrium Method for the temporary shoring facilities reinforced by soil-nailing was proposed, which is based on the stability for the horizontal displacement. In this study, the relation of the internal friction angles of the ground and the vertical excavation depths was arranged, which is satisfying the stability on the horizontal displacement by using the verification of the Limit Equilibrium Method. And then, the rational reinforcing length of soil-nailing was proposed for the critical areas. In addition, the modified safety ratio satisfying the stability on the horizontal displacement was proposed, when the Limit Equilibrium Method was applied to the vertical excavation walls reinforced by soil-nailing.