• KDI Journal of Economic Policy
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• 제39권2호
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• pp.25-51
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• 2017

This paper employs an Overlapping Generations Model to quantify the impacts of Korea's demographic transition toward an older population on the total output growth rate. The model incorporates the projected population through 2060 according by Statistics Korea. The effects of the low fertility and increased life expectancy rates are studied. The model is considered suitable for analyzing the effects of demographic changes on the Korean economy. Under the assumption that the TFP growth rate will not slow considerably in the future, remaining at 1.3% per annum, the gross output growth rate of the Korean economy is projected to slow to 1.1% per annum in the 2050s, from 4.0% in the 2000s. The shrinking workforce due to the decline in fertility plays a significant role in the deceleration of the Korean economy. The increased life expectancy rate is expected to mitigate the negative effect, but the magnitude of its effect is found to be limited.

• 대한기계학회논문집A
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• 제28권6호
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• pp.791-798
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• 2004

Fatigue crack initiation lives of round cylindrical notch specimen were investigated. Firstly, local strain approximation methods, such as the modified incremental Neuber's rule and the modified incremental Glinka's equivalent strain energy density(ESED) rule, were used to get multiaxial stress and strain state components at the notch tip. Based on the history of local stress and strain, multiaxial fatigue models were used to obtain fatigue crack initiation lives. Because the solution of Neuber's rule and Glinka's ESED rule make the upper and lower bound of local strain approximations, fatigue crack initiation lives are expected to place between life predictions by two local strain approximations. Experimental data were compared with the fatigue crack initiation life prediction results.

• 품질경영학회지
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• 제25권3호
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• pp.11-21
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• 1997

The mean residual life(MRL) function gives the expected remaining life of a item at age t. In particular F is said to be an increasing intially then decreasing MRL(IDMRL) distribution if there exists a turing point $t^*\ge0$ such that m(s)$\le$ m(t) for 0$$\le s$\le$ t $t^*$, m(s)$\ge$ m(t) for $t^*\le$ s$\le$ t. If the preceding inequality is reversed, F is said to be a decreasing initially then increasing MRL(DIMRL) distribution. Hawkins, et al.(1992) proposed test of H0 : F is exponential versus$H_1$: F is IDMRL, and $H_0$ versus $H_1$' : F is DIMRL when turning point is unknown. Their test is based on a complete random sample $X_1$, …, $X_n$ from F. In this paper, we generalized Hawkins-Kochar-Loader test to random censored data.

• 한국수학교육학회지시리즈A:수학교육
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• 제24권2호
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• pp.117-125
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• 1986

The education of mathematics in generalized schooling should aim to concentrate on the cultivation of mathematical abilities necessary for social life. Mathemeatical abilities for social life run as follows: A. Utilitarian aspects 1. classification and numbers 2. traffic network and connection of segments of lines 3. expectation of getting the winning number in a lottery 4. interests in dealing in unharvested rice crop B. Aesthetic aspects 1. finding the optimum value and 2. successful candidates in accordance with election methods Every nation has its own peculiar customs and circumstances. Therefore, in order to achieve the expected results, the education of mathematics should develop what every nation has on its own and apply them to school education.

• ETRI Journal
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• 제36권3호
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• pp.343-351
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• 2014

For the fine-pitch application of flip-chip bonding with semiconductor packaging, fluxing and hybrid underfills were developed. A micro-encapsulated catalyst was adopted to control the chemical reaction at room and processing temperatures. From the experiments with a differential scanning calorimetry and viscometer, the chemical reaction and viscosity changes were quantitatively characterized, and the optimum type and amount of micro-encapsulated catalyst were determined to obtain the best pot life from a commercial viewpoint. It is expected that fluxing and hybrid underfills will be applied to fine-pitch flip-chip bonding processes and be highly reliable.

• 대한치과의사협회지
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• 제58권10호
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• pp.649-655
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• 2020

As a dentist, we should be prepared for emergencies that can occur at any time in dental practice. In addition, we must be able to provide first aid to patients with the latest knowledge when an emergency actually occurs. It has been revised every five years since the American Heart Association published advanced cardiovascular life support (ACLS) guidelines. The current final guideline is the 2015 version. It is expected that the 2020 version will be released around the winter of 2020. Therefore, at this point, the latest version (2015 ver.) will be important. Many changes were made from 1995 to 2015. I would like to summarize the parts of the revised parts that remain important.

• 펄프종이기술
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• 제42권1호
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• pp.13-19
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• 2010

Four waste paper mills in Korea, where multifractors, devices for fiber fractionation, were installed, were selected to investigate how effectively and how differently the multifractors were used. They all used slot-type screens. Effective fiber fractionations by fiber length were expected by the multifractors, but in reality, they were used for selecting fiber furnishes that were flexible and hydrated. Flakes, which meant large fiber bundles, were rejected effectively by the multifractors. There existed a high regression coefficient between the fiber length differences and the freeness differences of the accepted and the rejected fiber furnishes.

• International Journal of Reliability and Applications
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• 제17권1호
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• pp.85-105
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• 2016

In this paper accelerated life testing is incorporated in quality control technique of acceptance sampling plan to induce early failures in high reliability products.Stress under accelerated condition can be applied in constant-stress, step-stress and progressive-stress or combination of such loadings. A ramp-stress results when stress is increased linearly (from zero) with time. In this paper optimum failure-censored ramp-stress accelerated life test sampling plan for log-logistic distribution has been formulated with cost considerations. The log-logistic distribution has been found appropriate for insulating materials. The optimal plans consist in finding optimum sample size, sample proportion allocated to each stress, and stress rate factor such that producer's and consumer's interests are safeguarded. Variance optimality criterion is used when expected cost per lot is not taken into consideration, and bilevel programming approach is used in cost optimization problems. The methods developed have been illustrated using some numerical examples, and sensitivity analyses carried out in the context of ramp-stress ALTSP based on variable SSP for proportion nonconforming.

• 한국기계가공학회지
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• 제13권3호
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• pp.56-62
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• 2014

During the hot forging process, the most common cause of tool failure is wear. Tool wear results in the gradual loss of part tolerances, after which eventually the tool must be replaced or repaired. In order to maximize the lifetimes of forging tools, it is important to investigate the wear mechanisms of these tools. In this study, the hot forging of the outer race of an automotive constant-velocity joint was analyzed by a finite element method to investigate the wear distribution, especially the amount and location of the maximum expected wear damage, using Archard's wear model, which was modified considering the forging temperature. Forging analyses were carried out after modifying blocker forging tools based on established versions. The modified blocker tools resulted in an increase in the tool life up to 31% with a finisher punch.

• 대한가정학회지
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• 제37권12호
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• pp.13-28
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• 1999

This study aimed to analyze the process of courtship form having date and marriage toward women who had job before marriage. The objects were 27.36 years old and had 9.59 months marital life at average. This study conducted structured questionnaires using the reflection of spouse selection procedure. By using collected data through questionnaires, it conducted descriptive statistics, cluster analysis and t-test. The type of marriage would be divided into the emotional marriage group and the implemental marriage group The emotional marriage group had longer dating time and more satisfaction of spouse selection than the implemental group. On value variable, the emotional marriage group had more subjective selection standard and more expectation social and emotional benefit than the latter group. On search variable, the emotional marriage group estimated the relation stability and satisfied the relation with spouse more than the implemental marriage group and expected the less possibility to meet new partner.