• 대한기계학회논문집A
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• 제24권8호
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• pp.1958-1967
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• 2000

Rapid Prototyping( RP ) has been increasingly applied in the process of design and development of new products. RP can shrink the time and expense required to bring a new product from initial concept to production. However, the necessity of using RP for short-run manufacturing is continuously driving a development of a cost-effective technique that will produce completely-finished quality parts in a very short time. To meet these demands, the improvements in production speed, accuracy materials, and cost are crucial. Thus, a new hybrid-RP system performing both deposition and machining in a station is proposed in this paper. It incorporates both material deposition in layers and material removal from the outer surface of the layer to produce the required surface finish. The new hybrid-RP system can dramatically reduce the total build time and fabricate largo-sized and freeform objects because it uses very thick layers, i.e.

• 한국인구학
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• 제14권1호
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• pp.1-25
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• 1991

The Purpose of this study is to analyze the contribution of the total human capital formation to economic growth in Korea. In order to assess the contribution of the total human capital formation to economic growth, aggregate production functions are estimated using two ways of ordinary least squares and polynomial distributed lags based on 1955 - 1988 time series data in Korea. The total amount of investment in human capital is calculated by adding each amount of investment in formal education, vocational training, inter-provincial migration, and health in pecuniary terms. The findings of this study could be summarized as follows ; (1) If we enumerate the variables in good order according to the importance, we get the following ; namely, total number of labor force, inter-provincial migration, vocational training, health, physical capital, and formal education. (2) The contribution of the human capital to economic growth is much more larger than that of physical capital. In particular, it appears that inter-provincial migration and vocational training make a great contribution to economic growth. (3) It appears that investment in formal education has a continuous effect for fifteen years and maximum effect is observed approximately eight years later. In the case of vocational training, the effect of investment lasts for about 12-14 years and its effect on economic growth reaches maximum with the passage of seven to eight years after initial investment. (4) Investment in vocational training contributes more in the long run compared with investment in formal education. The effect of investment in formal education lasts longer than that of vocational training, while the effect of investment in vocational training is considerably larger in the short run compared with the investment in formal education.

• 농업과학연구
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• 제47권3호
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• pp.533-544
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• 2020

In this paper, we conducted a dynamic ex-post assessment on the grape business cessation support System. Based on the analysis results, in the short term, there was an increase in grape price due to a decrease in production and accompanying increases in the prices of consumption substitution items. However, in the long run, grape prices fell again due to an increase in grape production because of the entry of new grape farmers and the growth of adult grape trees. In addition, the analysis showed that the balloon effect caused by the conversion of crops caused indirect damage such as an increase in the production volume of substitution crops and a decrease in prices. When analyzing the social welfare measurement, the results showed that the support system for business cessation increased the overall social welfare due to an increase in producer welfare because of a price increase in the short term, but in the long term, both producer and consumer welfare decreased. In the end, it is necessary to review the system because the government's intervention may cause market distortion and inefficient resource allocation. Above all, it is necessary to minimize the indirect effect of the industry's contraction and balloon effect due to excessive business cessation. For this, conditional support should be provided in parallel with post management rather than unconditional support. In addition, it is necessary to provide a strategic support system that considers substitution items in addition to those items to be supported.

• 대한기계학회논문집A
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• 제24권9호
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• pp.2235-2245
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• 2000

The necessity of using rapid prototyping(RP) for short-run manufacturing is continuously driving a development of a cost-effective technique that will produce completely-finished quality parts in a very short time. To meet these demands, the improvements in production speed, accuracy, materials, aid cost are crucial. Thus, a new hybrid-RP system performing both deposition and machining in a station is proposed. For the new hybrid RP process to maintain the same degree of process automation as in currently available processes like SLA or FDNI, a sophisticated process planning system is developed. In the process planner, CAD models(STEP AP203) are partitioned into 3D manufacturable volumes called 'Ueposition feature segment"(DFS) after machining features called "machining feature segmenf'(MFS) are extracted from the initial CAD model. Once MFS and DFS are identified, the process planner arranges them into a chain of processes and automatically generates machining information for each DFS and MFS. The goal of this paper is to present a framework for a process planning system for hybrid RP processes and to outline the geometric algorithms involved in developing such an environment.

• 기술사
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• 제45권1호
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• pp.45-48
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• 2012

이번 일본 북동해안에서 발생한 지진해일에 대한 원인과 영향을 살펴보고 방재대책과 방재대응 시스템의 필요성을 고찰해 보았다. 기술적으로 지진발생을 예측할 수는 없으나 발생한 해일이 해안에 도달하는 시간은 예측이 가능하므로 재난에 대비하기 위한 예보경보시스템 구축이 필요한데 이를 위해 지진해일 감시를 위한 관측시스템 구축과 국가간 긴밀한 협조체계가 필요하다. 또한 방재시설, 방조수문, 육갑, 항구방파제, 하천제방 등 방재구조물의 종류와 효과를 살펴보았다. 우리나라의 경우는 무엇보다 지진해일에 의한 재해정보도의 제작, 보급이 필요하며 해안에 거주하는 주민을 대상으로 지속적인 교육, 훈련을 통해 유사시 인명과 재산의 피해를 최소화하는 노력이 시급한 것으로 판단된다.

• 통상정보연구
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• 제7권2호
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• pp.75-94
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• 2005

This study is focused on evaluating the computer-integrated just-in-time (CI-JIT) production system of a semi-conductor manufacturing firm in Korea. Approaching the mid-1980s, the emphasis was on low price, low-cost operations, and quality, especially in USA. American companies have shifted output to low-wage countries like the Philippines, Korea, Japan, Malaysia and allied countries that can make quality products at low prices. Korea and other Asian countries forego short-term profits to gain a solid foothold in a product market, recognizing that larger market share leads to lower cost and higher profit in the long run. They bring manufacturers and suppliers together to improve material management and operation management, using project teams that investigate topics, such as Just-In-Time(JIT)manufacturing, among others. The "Kanban" word means "card" in Japanese, and is used to indicate the desired final delivery schedule. The operation for a particular item produced is scheduled for a specific time. The same process is extended to the external suppliers. More recently, the cards are gradually being replaced by electronic procedures that follow the same concept. Its capacity must be capable of handling the various transactions required by the JIT coverage as well as some allowances for expanded applications.

• 국제지역연구
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• 제15권1호
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• pp.495-522
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• 2011

이 연구는 탄소세를 도입하고 있는 핀란드, 네덜란드, 뉴질랜드, 스웨덴, 영국 등의 국가들을 중심으로 탄소세 도입 전후로 이산화탄소배출량, 에너지 사용 및 경제성장간의 상관관계를 단기동태 벡터오차자기수정모형을 이용하여 분석하였다. 첫째, 핀란드, 뉴질랜드, 스웨덴의 경우 먼저 변수사이의 공적분 관계에서 모든 변수에서 계수값이 부(-)로 나타났으며(너머지 국가에서는 이 값이 정(+)으로 나타남), 이산화탄소배출량 방정식을 제외하고 모두 통계적으로 유의하게 나타나고 있다. 이것은 장기적인 균형관계로부터의 이탈이 발생하는 경우 이산화탄소배출량을 제외한 모든 변수들이 감소하는 방향으로 조정된다는 것을 의미한다. 둘째, 탄소세의 도입이 이산화탄소의 배출에 어떠한 영향을 주었는지 분석한 결과는 핀란드, 뉴질랜드, 스웨덴의 경우 변수사이의 공적분 관계에서 모든 변수에서 계수값이 부(-)로 나타났다(나머지 국가에서는 이 값이 정(+)으로 나타남). 한편 탄소세 도입 이후의 단기적인 동태분석의 경우 뉴질랜드와 스웨덴의 경우는 핀란드와 유사한 결과를 보여주고 있으며, 결과적으로 탄소세 도입 이후에 탄소배출량 및 에너지사용량이 감소했다는 증거는 단기적인 관점에서 제시하기 어렵다. 그러나 네덜란드와 영국의 경우 탄소배출량의 증가는 오히려 산출량을 감소시키고 있다는 결과가 나왔다. 이것은 탄소배출량을 줄이기 위하여, 네덜란드와 영국의 경우에는 보다 공격적인 정책이 실시될 필요가 있다는 것을 의미한다.

• 산업경영시스템학회지
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• 제33권3호
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• pp.146-153
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• 2010

When the production run is short and process parameters change frequently, it is difficult to monitor the process using traditional control charts. In such a case, the coefficient of variation (CV) is very useful for monitoring the process variability. The CV control chart is an effective tool to control the mean and variability of process simultaneously. The CV control chart, however, is not sensitive at small shifts in the magnitude of CV. The CV-EWMA(exponentially weighted moving average) control chart which was developed recently is effective in detecting a small shifts of CV. Since the CV-EWMA control chart scheme can be viewed as a weighted average of all past and current CV values, it is very sensitive to small change of mean and variability of the process. In this paper, we propose an FIR(Fast initial response) CV-EWMA control chart to improve the sensitivity of a CV-EWMA scheme at process start-up or out-of-control process. Moreover, we suggest the values of design parameters and show the results of the performance study of FIR CV-EWMA control chart by the use of average run length(ARL). Also, we compared the performance of FIR CV-EWMA control chart with that of the CV-EWMA control chart and we found that the CV-EWMA control chart gives longer in-control ARL and much shorter out-of-control ARL.

• 자원ㆍ환경경제연구
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• 제24권4호
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• pp.709-725
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• 2015

본 연구에서는 벡터오차수정모형을 이용하여 양식 넙치 산지시장의 출하량 조절이 양식 넙치가격에 미치는 영향을 검토하고자 하였다. 이를 위하여 2007년 1월 1일부터 2013년 6월 30일까지의 1kg 크기에서 형성되고 있는 양식 넙치의 위판가격과 출하량 자료를 이용하였으며, 가격과 출하량 시계열의 정상성 검정, 공적분 검정, 벡터오차수정모형(VECM)의 추정결과를 포함하고 있다. 본 연구의 주요 실증결과는 다음과 같이 요약할 수 있다. 첫째, 가격과 출하량은 확률보행과정을 따르고 있으며, 1차 적분 시계열임을 확인하였다. 둘째, 가격과 출하량 간에 공적분관계가 성립하고 있음을 보여주며, 이들 변수가 밀접히 연계되어 있음을 보여주었다. 셋째, 가격과 출하량 간 일시적인 불균형이 발생했을 때, 장기적으로 출하량 조정을 통해 불균형 상황이 72.1% 정도 해소되며, 가격 변화를 통해 불균형상황이 0.5% 정도 해소되고 있음을 보여주고 있어 가격과 출하량 간 일시적인 불균형이 발생했을 때, 피드백효과가 존재하나 출하량 조정에 의해 해소되고 있음을 보여주었다. 마지막으로, 출하량 변화율이 단기적으로 가격 변화율을 선도하며, 출하량의 감소(증가)가 가격의 상승(하락)을 초래하고 있음을 확인할 수 있다.

• 산업경영시스템학회지
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• 제31권4호
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• pp.114-120
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• 2008

The control chart is widely used statistical process control(SPC) tool that searches for assignable cause of variation and detects any change of process. Generally, ${\bar{X}}-R$ control chart and ${\bar{X}}-S$ are most frequently used. When the production run is short and process parameter changes frequently, it is difficult to monitor the process using traditional control charts. In such a case, the coefficient of variation (CV) is very useful for monitoring the process variability. The CV control chart is an effective tool to control the mean and variability of process simultaneously. The CV control chart, however, is not sensitive at small shift in the magnitude of CV. In this paper, we propose an CV-EWMA (exponentially weighted moving average) control chart which is effective in detecting a small shift of CV. Since the CV-EWMA control chart scheme can be viewed as a weighted average of all past and current CV values, it is very sensitive to small change of mean and variability of the process. We suggest the values of design parameters and show the results of the performance study of CV-EWMA control chart by the use of average run length (ARL). When we compared the performance of CV-EWMA control chart with that of the CV control chart, we found that the CV-EWMA control chart gives longer in-control ARL and much shorter out-of-control ARL.