• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6D
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• pp.753-760
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• 2009

This study analyzed the fluctuation of the construction material cost from 2001 to 2008 in Busan to examine the effect of the fluctuation of the construction material cost on lotting price of the multi family attached house. The major findings are as follow. First, as the result of the analysis on four materials such as reinforced bar, remicon, PHC piles, Copper Tubes, those take largest portion of construction cost, it was found that the there is wide difference in price fluctuation of the each materials. The reinforced bar and Copper Tubes showed high price increase by an average 14.03% and 14.91% per year while remicon, PHC piles remained almost unmoved by an average 0.86% and 2.41%. Second, According to the result of the analysis on the mutuality between the fluctuation of the construction material cost and the lotting price of the multi-family attached house, it was found that the fluctuation of the construction material cost have the most enormous effect on the sale price of the multi-family attached house, when there is 3 month time lag in reinforced bar, remicon, PHC piles, Copper Tubes, commonly. Also this mutuality continues to 6 month, 9 month and 1 year, although it decrease a little bit.

• Information Systems Review
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• v.21 no.1
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• pp.91-111
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• 2019

Around the end of 2017, the investment fever for cryptocurrencies-especially Bitcoin-has started all over the world. Especially, South Korea has been at the center of this phenomenon. Sinceit was difficult to find the profitable investment opportunities, people have started to see the cryptocurrency markets as an alternative investment objects. However, the cryptocurrency fever inSouth Korea is mostly based on psychological phenomenon due to expectation of short-term profits and social atmosphere rather than intrinsic value of the assets. Therefore, this study aimed to analyze influence of people's social sentiment on price movement of cryptocurrency. The data was collected for 181 days from Nov 1st, 2017 to Apr 30th, 2018, especially focusing on Bitcoin-related post in Twitter along with price of Bitcoin in Bithumb/UPbit. After the collected data was refined into neutral, positive and negative words through sentiment analysis, the refined neutral, positive, and negative words were put into regression model in order to find out the impacts of social sentiments on Bitcoin price. After examining the relationship by the regression analyses and Granger Causality tests, we found that the positive sentiments had a positive relationship with Bitcoin price, while the negative words had a negative relation with it. Also, the causality test results show that there exist two-way causalities between social sentiment and Bitcoin price movement. Therefore, we were able to conclude that the Bitcoin investors'behaviors are affected by the changes of social sentiments.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.45-52
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• 2015

Fiber-reinforced polymer (FRP) has been generally accepted by civil engineers as an alternative for steel reinforcing bars (rebar) due to its advantageous specific tensile strength and non-corrosiveness. Even though some glass fiber reinforced polymer (GFRP) rebars are available on a market, GFRP is still somewhat uncompetitive over steel rebar due to their high cost and relatively low elastic modulus, and brittle failure characteristic. If the price of component materials of GFRP rebar is not reduced, it would be another solution to increase the performance of each material to the highest degree. The tensile strength generally decreases with increasing diameter of FRP rebar. One of the reasons is that only fibers except for fibers in center resist the external force due to the lack of force transfer and the deformation of only outer fibers by gripping system. Eliminating fibers in the center, which do not play an aimed role fully, are helpful to reduce the price and finally FRP rebar would be optimized over the price. In this study, the effect of the hollow section in a cross-section of a GFRP rebar was investigated. A GFRP rebar with 19 mm diameter was selected and an analysis was performed for the tensile test results. Parameter was the ratio of hollow section over solid cross-section. Four kinds of hollow sections were planned. A total of 27 specimens, six specimens for each hollow section and three specimens with a solid cross-section were manufactured and tested. The change by the ratio of hollow section over solid cross-section was analyzed and an optimized cross-section design was proposed.

• Korean Journal of Construction Engineering and Management
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• v.14 no.4
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• pp.24-34
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• 2013

Since 2004, the government decided to gradually introduce Actual Cost Data into cost estimate for improving problems of below-cost tendering and to reflect fair market price through competition and carry contract efficiently. However, there are many concerns that Actual Cost Data has not reflected real market price, even that has contributed to reduce the government's budget. General construction firm's burden for labor cost is imputed to specialty contractors and eventually it becomes construction worker's burden. Therefore, realization of Actual Cost Data is very important factor to settle this system. To understand realization level and make short term forecast, this paper drew construction group of which labor cost constitutes more than 95% of direct cost, and compares their Actual Cost Data with relevant skilled workers's unit wage and predicts using time series analysis. The bid price which is not be reflected market price accelerates work environment changes and leads to directly affect such as late disbursement of wages, bankruptcy to workers. Therefore this paper is expected to be used to the preliminary data for solving the problem and establishing improvement of Actual Cost Data.

• Journal of Korean Society of Forest Science
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• v.99 no.4
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• pp.479-486
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• 2010

We analyzed the relationships between the daily yield and quality of pine-mushroom to predict the annual production pattern and unit price of the mushroom with the records of pine-mushroom trade at Yeongdeok forestry cooperative's market for nine years (2000~2008). Although there were some exceptions due to extreme drought or extraordinary temperature, the production ratio of high quality (first and second grade) was more than 50% in early stage and decreased, while that of low quality (pileus opened and defected ones) showed increasing pattern after the production reached in peak. The ratio of high quality and that of low quality were reversed 1~9 days before the mushroom production reached the acme of daily yield, which allowed us to predict that the mushroom production would be decreased when the ratio of low quality overcomes that of high quality. The ratio of high quality preceded about 3~4 days prior to that of daily yield, and the mushroom yield showed significant correlations with the ratio of high quality mushroom prior to 3~4 days of the day with the coefficient larger than 0.5 (r=0.51 for 3 days and r=0.54 for 4 days). Thus, we concluded that the analysis of grade distribution of pine-mushroom at the market may provide a significant clue to predict production pattern of the mushroom. In addition, the price of high quality pine-mushroom showed clear negative correlations with the yield. Thus, the analysis may take a good role for the trading of pine-mushroom with providing information for predicting the price of pine-mushroom.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.83.2-83.2
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• 2010

최근, 원유 가격의 상승으로 인해 태양에너지에 대한 관심이 크게 증가되고 있다. 그러나 이러한 태양전지용 Si(SoG-Si)의 대부분을 차지하는 태양전지급 다결정 실리콘 원료를 대부분 수입에 의존하고 있는 실정이다. 이에 대한 기술적 대응으로서 최근에는 고비용의 기상법을 해결하기 위하여 야금학적인 정련법을 이용한 제조기술 개발이 세계적으로 주목받고 있으며, 야금학적 정련기술은 지적재산권에 관한 기술적 배타성을 제고 할 수 있을 뿐 만 아니라 기상법의 Si 대비 낮은 품위 에도 불구하고 태양전지용 실리콘의 사용가능성을 제시함으로서 활발한 연구와 함께 실용화기술로 대두되고 있다. 그러므로 본 연구는 기존 사용 중인 고가의 기상법 폴리실리콘 제조와 달리, 생산 가격경쟁력이 있는 규석광으로부터 고순도금속 및 태양전지급 폴리실리콘 생산 연속 종전기술을 개발하고자 하였다. 금속급 Si(이하 MG-Si)으로부터 경제적인 SoG-Si을 제조하기 위한 공정 개발을 일환으로 MG-Si 중 불순물인 P 원소를 효과적으로 정련할 수 있는 슬래그 정련기술 개발과 슬래그설계 기술개발을 기본목표로 설정하여 고찰하였다. 용융 Silicon과 슬래그계면에 설정되는 산소분압제어에 따른 슬래그의 P의 이온 안정성을 변화시킴으로서, MG-Si중 P를 분리제거를 기본개념으로 설정하였다. 염기성 산화물로 산소이온이 공급됨을 이용하여 염기도에 따른 분배비를 고찰한 결과, CaO의 활동도가 증가함에 따라 슬래그 중 $O^{2-}$의 활동도와 함께 phosphide 이온의 안정성이 증가함을 확인하였다. 그리고 슬래그로부터 실리콘 중 Ca의 용해도에 따른 분배비를 확인하기 위해 실험 후 Si에서 Ca의 성분을 분석한 결과, 실리콘 중 Ca 용해도는 염기도($a_{CaO}/\sqrt{a_{SiO_2}}$)의 증가와 함께 증가하였으며, Ca의 용해도 증가는 탈린능을 증가시킨다는 것을 알 수 있었다. 또한 수소분압을 변화시켜 인의 증기압변화 및 기화정련 효과를 알 수 있었으며, acid leaching을 통해 잔존해있는 불순물을 추가적으로 정련될 수 있는 가능성을 확인할 수 있었다.

• Environmental and Resource Economics Review
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• v.15 no.2
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• pp.297-318
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• 2006

Imported natural gas has been consumed by urban gas use and generation sector in Korea. The share of generating sector in total demand for natural gas is only 33% at 2000. This paper examines the potential of natural gas use in generation sector in the future. We build some hypothetical but realistic scenarios reflecting rapidly changing economic environment. We used standard programs for plant mix decision under those scenarios. We found that it is very likely to have high gas demand in the future, if we remove the cross-subsidizing price structure.

• Journal of the Economic Geographical Society of Korea
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• v.16 no.3
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• pp.389-407
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• 2013

The objective of this research is to provide an understanding of how coffee production has been taking place since the coffee industry in Vietnam came out in the global market after Doi Moi. Current research tries to understand how the local households of coffee production adjusts to their production process according to internal and external influences. In order to explore coffee production in the level of local and household units, the structure of coffee production in Dak Lak is first explored in terms of production and sales with the cases from two communes. The examination reveals that general characteristics of coffee crops that would reflect coffee production structure. Further, this study interrogates farmers' response to reflect some direct and indirect influences in recent years. That shows how the elements of coffee production in global market induce a change of coffee production in the study area. Those aspects are analyzed in relation to yearly coffee price fluctuation and diversification. Also, this research explores some of farmers' responses toward the environmental friendly coffee production.

• Journal of the Korean Regional Science Association
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• v.31 no.2
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• pp.63-77
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• 2015

Effects of shifting trend from Chonsei to monthly-rent and the changes in rental housing prices upon the welfare of tenants has been analyzed. In 2014, welfare of tenants has been found to be decreased by 660 billion Korean Won due to the change in rental housing prices. From the point of view of the welfare of tenants, it has been found that monthly-rent stabilizing policies are 1.47 times more effective than Chonsei price stabilizing policies. The effect of monthly-rent stabilizing policies has been found to be increased with the increase in the proportion of monthly-rent transaction, the decrease in the speed of the shifting trend from Chonsei to monthly-rent, the decrease in interest rate, the decrease in the proportion of variable deposit in monthly-rent, the decrease in the proportion of debt in Chonsei deposit. These findings indicate that the relative importance of monthly-rent stabilizing policies will be increased in the future.

• Resources Recycling
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• v.32 no.6
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• pp.67-78
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• 2023

The rare metals used as raw materials in high-tech industries undergo changes in demand structures and supply chains following domestic industrial structural shifts and technological advancements, exhibiting high price volatility. Therefore, it is necessary to periodically analyze changes in the demand structures of rare metals. Since domestic demand for most rare metals relies on imports in Korea, the changes in domestic demand for rare metals can be identified by analyzing changes in their trade structure. In the present study, we analyze the changes in trade volume, trade growth rate, trade rankings, and trading countries from 2000 to 2022 for 35 rare metals, categorized into five types-ores, metals, alloys, compounds, and scrap. The trade of the raw materials of rare metals in Korea has generally increased since the 2000s, except for a significant decline in 2009 and 2016. The total trade volume, encompassing both exports and imports, has increased by approximately tenfold in 2022 compared to 2001. Until the mid-2010s, the trade of the raw materials of rare metals was primarily focused on those used in steel-manufacturing such as silicon, nickel, chrome, molybdenum, manganese, and others. However, after that period, there has been an increase in the trade of platinum group metals like palladium, rhodium, platinum, and the raw materials of rare metals for secondary battery-manufacturing such as lithium and cobalt. Particularly in 2022, lithium has become the largest share in trade of the raw materials of rare metals in Korea, due to the price surge and increase in demand.