• Journal of Navigation and Port Research
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• v.38 no.1
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• pp.65-71
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• 2014

Gyeongbu and Namhae expressways in the country, are the major arterial highways which are connected with the Busan port in the north-south and east-west directions, respectively, and required to study the traffic characteristics about the hourly volume factors(K-factor) by concentrated midium-size and large-size cargo trucks of 20% or higher in expressways. We therefore attempted to predict the K-factor in expressways through the correlation analysis between K-factor and K-factor estimates on the basis of the short-term VDS data collected at the basic segments of the above major expressways. As a result, power model appeared to be appropriate in predicting K-factor by the K-factor estimate based on VDS data for 7 days with a high explanatory power and validity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.47-54
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• 2014

Endurance of ship hull can be estimated by existing regulations and fatigue estimation methods. These can be applied to the hull materials that are recommended by ship regulations but can't be applied to new materials. In this study, structural force in the worst sailing condition is obtained by the acceleration measurement test of small polyethylene boat and the endurance of small polyethylene hull is estimated by rainflow cycle counting method and linear cumulative damage rule. Maximum Von-Mises stress on the polyethylene boat is 1.8MPa and much lower than the fatigue strength of at least 5.9MPa for the fatigue life of $1{\times}10^9$ cycles. Fatigue life of the polyethylene boat hull is estimated to be 6,229 years.

• Analytical Science and Technology
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• v.14 no.4
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• pp.364-370
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• 2001

The corrosion behaviors of reinforcing steels were investigated under chloride ion contained in cement mortar including gypsum by the implementation of half cell potential measurement, EPMA analysis, exterior features, weight loss and extraction experiment. The acceleration test equipment accelerated corrosion of mild steel bar in a short period of time. From observing the exterior features and weight loss, we could evaluate the measure of corrosion. Also, from the extraction experiment of ${SO_4}^{2-}$ with $Cl^-$ ions contained in the ceramic mortar, we concluded that ${SO_4}^{2-}$ ion affected more on the corrosion mechanism in comparison to pH.

• Journal of Korea Port Economic Association
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• v.33 no.3
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• pp.139-154
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• 2017

As competition in domestic and overseas ports intensify, new and small domestic ports are realizing certain limitations to independently secure competitiveness. This study collected data over 60 months with five modifications for container and general cargo volume around Gyeongin Port. Short-period (12 months) cargo volume was forecasted, which revealed the need for a middle-to-long-term development plan. First, the hinterland logistics complex of Gyeongin Port is expected to contribute to the coastal maritime facility through the quasi-public system for fishery product transportation and passenger services. It proposes to achieve this by opening channels to and from China for precision machinery, home network systems, LEDs, and machine industry items. second, specializing the ultra-light cargo transport route, and connecting the coastal island areas of the 5 West Sea Islands to Ara Waterway (Integrated Fishery Product Center of the 5 West Sea Islands). Third, on the basis of organic cooperation of government? local government ? port, the incentive and pre-circular support system would be required, and lastly, it shall carry out the adjustment of functions in nearby ports and specialization strategy simultaneously through the integrated operation of the ports in the capital areas.

• KDI Journal of Economic Policy
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• v.15 no.3
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• pp.53-93
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• 1993

본고(本稿)는 6.25전쟁(戰爭)이후 한국경제(韓國經濟)가 겪은 아홉번의 경기순환(景氣循環)으로부터 순환(循環)의 특징(特徵)과 양태(樣態)를 정리한 것이다. 경기순환(景氣循環)의 특징은 경기순환(景氣循環)의 지속기간(持續期間), 순환심도(循環深度), 변동성(變動性), 공행성(共行性) 및 시차성(時差性), 해외경기순환(悔外景氣循環)과의 관계(關係) 등 여섯가지 면에서 살펴보였으며, 순환양태(循環樣態)는 순환기별(循環期別)로 정리하였다. 우리 경제를 순환기별(循環期別)로 살펴볼 때 경우에 따라서는 경기과열(景氣過熱)을 식히기 위해 실시한 정책이 세계경제여건의 악화와 맞물려 경기(景氣)를 급냉(急冷)시킨 시기도 있었으며, 반대로 경기침체기(景氣沈滯期)에 도입한 내수부양정책(內需浮揚政策)에 기대와는 달리 경기(景氣)를 급격히 과열시켜 단기간내에 물가(物價)를 급등시키고 국제수지(國際收支)를 악화시킨 경우도 있었다. 경기조절(景氣調節)을 위해 실시한 정책이 자칫하면 서다가다(stop-go)를 반복하여 국민경제에 오히려 부담을 줄 가능성이 있기 때문에 정책결정자(政策決定者)는 항상 경기조절(景氣調節)을 위한 최적(最適)의 정책(政策)을 선택해야 하는 부담을 안고 있다. 특히 석유파동(石油波動)이나 UR타결과 같은 세계경제질서(世界經濟秩序)의 변동이 발생한 경우에는 가급적이면 그 충격(衝擊)이 경제에 서서히 흡수되도록 적절한 정책(政策)을 구사해야 한다. 경기정책(景氣政策)은 장기성장(長期成長)을 제고(提高)시키는 방향으로 전전되어야 하기 때문에 정책(政策)의 선택은 매우 산중하제 결정될 수밖에 없다. 또한 1953년 이후 지금까지 겪은 아홉번의 경기순환(景氣循環)과 각종 경기대책(景氣對策)의 실시 경험으로부터 정부(政府)는 추후 경기조절정책(景氣調節政策)의 시행과정에서 불가피하게 야기되는 문제점을 극소화하고, 정책목표 달성의 효율성(效率性)을 제고(提高)하기 위해서 민간(民間)에 대한 대정부(對政府) 신뢰성(信賴性)을 쌓아 나가야 할 것이다.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.811-816
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• 1998

Rebar corrosion in cement mortar containing chloride ions was investigated by electrochemical AC impedance spectroscopy. Corrosion of mild steel bar was accelerated by an acceleration test equipment in short period. Impedance values obtained from AC-impedance method could be adapted to the proposed electrochemical equivalent circuit model and they were consistent with calculated values obtained by CNLS fitting method. The weight loss of rebar could be calculated by charge transfer resistance($R_2$) with time and it was close to real value.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.2
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• pp.172-180
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• 2016

A cubesat classified as a pico-satellite typically uses commercial-grade components that satisfy the vibration and thermal environmental specifications and goes into mission orbit even after undergoing minimum environment tests due to their lower cost and short development period. However, its reliability exposed to the physical environment such as on-orbit thermal vacuum for long periods cannot be assured under minimum tests criterion. In this paper, we have analysed the reliability and life prediction of the failure mechanisms of the cubesat mission board during its service life under the launch and on-orbit environment by using the sherlock software which has been widely used in automobile fields to predict the reliability of electronic devices.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.1
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• pp.16-22
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• 2010

Objective: Bisphosphonate related osteonecrosis of the jaw (BRONJ) is reported in patients taken bisphosphonate for a long time, however, the mechanism of osteonecrosis in BRONJ was not clarified yet. This study was designed to investigate the effect of short administraion zoledronate on the healing pattern of periosteum and sinus membrane after iliac bone graft into maxillary sinus. Methods: In this study, 18 Newzeland rabbits were used. The animals were divided into 2 group. In the experimental group, rabbits were treated with weekly peritoneal injection (0.06 mg/kg/week) of zoledronate for three times. In the control group, rabbits were treated with saline solution injection instead of zoledronate. Periosteum and sinus membrane were harvested from one rabbit of the experimental group and one of the control group in the fourth week. The autogeneous bone was harvested from ilium and grafted into maxillary sinus. The rabbits were sacrificed at 1, 2, 4 and 8 weeks after bone graft. The healing pattern of periosteum and sinus membrane were evaluated histologically. Results: Inflammatory reaction in the periosteum was less conspicuous and healing process appeared earlier in experimental group compared with control group at 1, 2, 4 weeks. There were no differences of microscopic findings of sinus membrane between both groups at any weeks. Conclusion: Short-term use of zoledronate decreased the inflammatory reaction and enhanced healing process in the periosteum. These findings suggest the possibility that zoledronte suppress the function of macrophages.

• Journal of the Korean GEO-environmental Society
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• v.8 no.6
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• pp.85-95
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• 2007

It is difficult for seismic survey to get hold of characteristic of coal shale fractured zone and if coal shale zone did not come into contact with underground water, coal shale zone has characteristic of good strength. But in case coal shale zone is exposed by excavation or blasting to the air, strength of coal shale zone decreases in short term and weathering of coal shale zone progresses rapidly. Therefore, the prediction of tunnel collapse is not easy in the coal shale zone and the great portion of tunnel collapse takes place in a moment. From a view point of strength, after twelve hours form result of point load test strength of coal shale decreases by fifty six percent when coal shale zone come into contact with ground water. The standard reinforcement design of coal shale fractured zone was presented in the paper.

• Journal of the Korean Geographical Society
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• v.35 no.5
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• pp.717-729
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• 2000

Housing prices in the Korean housing market dropped at an unprecedented magnitude in 1998 after the economic crisis. With the support of housing policies to boost depressed housing markets, house prices managed to bounce back after the mid-1999. During the period of housing price decline and of its recovery, the degrees of house price changes were not even across the country. The cities could be classified into four groups regarding the differential rates of house price changes. The cities which had higher rates of decrease also had higher rates of increase. On the other hand, some other cities continuously experienced a price fall during the recovery period although the rate of housing price changes were relatively low after the economic crisis. Throught the processes of administering housing market depression due to the crisis of the economy, the cities which could fully redeem the level of house prices in housing markets between the Seoul Metropolitan area and the other parts of the country has been widened.