• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.249-256
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• 1999

This study is intended to propose a systematic procedure for the development of the reliability-based seismic safety and cost-effective Performance criteria for design and upgrading of long span PC bridges. In the paper, a set of cost function models for life cycle cost analysis of bridges is proposed. The total life cycle cost functions consist of initial cost and direct/indirect damage costs considering repair/replacement costs, human losses and property damage costs, road user costs, and indirect regional economic losses. The damage costs are successfully expressed in terms of Park-Ang median global damage indices and damage probabilities. The proposed approach is successfully applied to model bridges in both regions of a moderate seismicity area like Seoul, Korea and a high one like Tokyo, Japan. It may be expected that the proposed approach can be effectively utilized for the development of cost-effective performance criteria for design and upgrading of various types of bridges as well as long span PC bridges.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.424-426
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• 2004

As power demand increases gradually, the call for underground transmission system increases. But it is very difficult and high in cost to construct new ducts and/or tunnels for power cables in metropolitan areas. HTS (High Temperature Superconducting) cable has the several useful characteristics such as increased power density, stronger fields and/or reduced losses. Therefore HTS cable can allow more power to be moved in existing ducts, which means very large economical and environmental benefits. In these days, companies world-wide have conducted researches on HTS cable. A development project for a 22.9kV class HTS cable is proceeding at a research center and university in Korea. In this paper, we investigate the expected price of HTS cable to have a merit in viewpoint of economic aspect. First, life-cycle cost of conventional cable is calculated and based on this, the expected price of HTS cable is evaluated, which HTS cable is competitive against conventional cable.

• Journal of information and communication convergence engineering
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• 제19권1호
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• pp.16-21
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• 2021

In this paper, to prevent accidents of school vehicles used by students, which have emerged as a continuous social problem, a boarding and leaving notification system using Bluetooth beacons is proposed. The platform structure uses Bluetooth, a smartphone, and an application, and provides real-time message reception between parents and teachers. It is not simply a system with Bluetooth capability alone, but also an IcT technology that is closely related to real life using two-way communication. The purpose is to provide user-friendly ICT technology as an integrated system for more practical effects. Two-way exchange of information between parents and teachers using cloud servers is made possible. By using this Bluetooth beacon notification system, safety accidents in student vehicles are reduced, which brings confidence from traffic accidents to schoolchildren of parents and teachers. Therefore, it is expected that parents and teachers are expected to improve their mental stability and quality of life from traffic accidents.

• Geomechanics and Engineering
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• 제32권5호
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• pp.513-521
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• 2023

Temperature is one of the most critical elements that influence the rutting and fatigue resistance of flexible pavements. Particularly in extreme hot regions in Saudi Arabia, high temperature would significantly reduce the rutting resistance of flexible pavements leading to reduction of pavement service life. Due to the impacts of global warming, average temperature in Saudi Arabia is expected to further increase by about 4℃ by the end of the 21st century. The substantial increase in average temperature will elevate the expected pavement maintenance and rehabilitation cost. This paper analyzes the structural effects of temperature on pavement using layered elastic analysis based on finite element techniques. The research team calculated the potential loss of pavement service life due to the projected temperature increase and climate change. The paper also analyzed potential impact of using carbon waste in asphalt concrete to tackle the derogatory impacts of temperature rise.

• 한국해양공학회지
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• 제33권5호
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• pp.435-446
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• 2019

Because offshore structures are affected by various environmental loads, the risk of damage is high. As a result of ever-changing ocean environmental loads, damage to offshore structures is expected to differ from year to year. However, in previous studies, it was assumed that a relatively short period of load acts repeatedly during the design life of a structure. In this study, the residual life of an offshore wind turbine support structure was evaluated in consideration of the timing uncertainty of the ocean environmental load. Sampling points for the wind velocity, wave height, and wave period were generated using a central composites design, and a transfer function was constructed from the numerical analysis results. A simulation was performed using the joint probability model of ocean environmental loads. The stress time history was calculated by entering the load samples generated by the simulation into the transfer function. The damage to the structure was calculated using the rain-flow counting method, Goodman equation, Miner's rule, and S-N curve. The results confirmed that the wind speed generated at a specific time could not represent the wind speed that could occur during the design life of the structure.

• 한국수정란이식학회지
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• 제31권3호
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• pp.267-272
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• 2016

Wholesale beef price is the critical factor for determining Korean native cattle, Hanwoo, farm's income in short-term. Wholesale beef price has seasonality due to high demand in Korean traditional holidays such as Korean thanksgiving day and lunar new year's day. Therefore, it is important to make reproduction and marketing plans for Korean Hanwoo farmers, in order to increase their farm income. However, there is no study available on changes in the expected farm income depending on reproduction and marketing schedules. This study analyzed the expected farm income per head depending on the monthly-based marketing schedules. The analysis was conducted based on the seasonality of wholesale beef price, reproduction efficiency, operating costs, relationship between carcass grade and slaughter age. The result shows that slaughter Hanwoo at the age of 29 months-old in August and January generating the highest expected farm income per head.

• 가족자원경영과 정책
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• 제9권1호
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• pp.113-130
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• 2005

The purpose of this study was to show the expected age of retirement of the couple, husband and wife, individually, the difference between the expected age of retirement of the husband and that of the wife, and to analyze contributing variables. The sample in this study numbered 517, of which 229 were husbands and 288 were wives. The independent variables were divided into three factors including personal, financial, and work related variables. The results of this study were as follows. Among two earner households, both husbands and wives expected the husband's age of retirement to be higher than of the wife. The difference between the husband's expected age of retirement and the wife's expected age of retirement was five years, on average. For the husband, personal, financial, and work related variables had effects on his expected age of retirement. However, for the wife it was only the perception of future work life and expected age of retirement of the partner which had very significant effects statistically. The variables affecting the difference between the expected age of retirement of the husband and that of the wife included the personal variables as well as interaction of the couple related variables. The results showed that first of all, the planning of retirement among two earner households needs to be focused on the couple rather than on the individual.

• 지식경영연구
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• 제8권1호
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• pp.49-63
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• 2007

This paper presents a new methodology that allows the influence of technological obsolescence and technology composite competitiveness to estimate technology economic life. In this paper the patent citation life analysis is used to estimate technology representative life, and technology residual life analysis is employed to estimate residual life using the linear and inverse functions. The technology economic life will be determined by combining the estimation results of patent citation life analysis and technology residual life analysis. This paper includes an example of applying it to the US patent data for 5 communications areas. Therefore, this logical concept can be applied usefully to determine the technology economic life and be expected to contribute to obtain credibility of technology valuation.

• 한국학교수학회논문집
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• 제1권1호
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• pp.97-109
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• 1998

The activities of teaching and learning are to try to reach the lesson object most closely in many ways. Considering that the lesson objects are to get the principle or law of a concept, to acquire the mathematical function, to master it through repeated exercises and to solve mathematical problems, we need many ways to reach such objects. Among the many ways, we can first think of one: the students will learn with curiosity and according to their own ability or advancing level in learning when teachers study and prepare necessary contents enough in advance by using computers, showing the right program to learners' needs. For example, defining definite integral by measuration by parts will help understand measuration by parts well and know the meaning of definite integral correctly, In teaching and learning by the use of this program, the educational effects are expected as follows. 1. It is thought that this program will stimulate the desire for and interest in learning because it used animation and acoustic effect. And voluntary and positive thinking activity will be shown. 2. It is expected that the conviction of formulas will be got and the concept of definite integral will be remembered firmly by showing how to measure the width of circle with the use of measuration by parts in various other ways instead of the ways used at present. 3. It is expected that students will feel the pleasure of mathematics in life when they recognize mathematical facts scattered really in our life rather than mathematical difficulties. 4. It is expected that the repeated review of programs already designed will remove the fear of incomplete parts and help review again. 5. It is certain that positive attitude in life will be formed as teacher-centered class is changed into learner-centered class and unwilling study is changed into self-oriented study. However, I think this program is insufficient for humanbeing-centered education given directly in contact with students on the ground of the variety in mathematical education and applications in many ways. And mechanically inhuman computers leave some solutions to be desired

• 한국조사연구학회지:조사연구
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• 제12권1호
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• pp.65-88
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• 2011

본 연구는 패널조사에 기초한 다중상태 생명표 모형을 활용하여 우리나라 중고령층의 근로와 은퇴 그리고 사망으로 이어지는 생애과정을 분석하고 있다. 또한 기존의 생명표 분석이 성별 차이만을 고려하였음에 비해 본 연구는 교육수준을 추가적으로 고려하여 생명표를 작성함으로써 근로 및 은퇴 생애과정에서 관측되는 사회계층별 이질성을 추가적으로 고려하고자 하였다. 분석 결과는 근로 및 은퇴 생애과정이 성별 그리고 교육수준별로 매우 이질적인 패턴을 보이고 있음을 보여 주었다. 성별 차이와 관련하여 여성은 남성에 비해 생존기간이 길지만 취업 기대여명이 낮음과 동시에 미취업 기대여명이 높게 나타남으로써 전체 생존 기간에서 미취업 기간이 차지하는 비중이 매우 높은 모습을 보여 주었다. 교육수준별 차이와 관련한 분석 결과는 전반적으로 취업 기대여명에서는 뚜렷한 차이가 관측되지 않는 반면, 미취업 기대여명에서의 격차가 유의미하게 나타남으로써 교육수준별 근로생애 차이는 대체로 미취업 기대여명에서의 차이임을 보여 주었다. 보다 구체적으로, 교육수준이 낮은 개인들은 교육수준이 높은 개인들과 유사한 수준의 취업 기대여명을 갖고 있지만, 미취업 기대여명이 유의미하게 낮음으로 인해 생존 기간의 보다 큰 비중을 노동시장에서 체류하고 있음을 보여 주었다.