• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.486-494
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• 2021

Watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) is sensitive to low temperature and shows retarded growth under 10℃. Although early transplanting guarantees higher returns, it requires cost and labor to maintain the appropriate temperature for plant growth. Therefore, cultivars tolerant to chilling stress is necessary to reduce the cost and labor requirements. The purpose of this study is to analyze data on plant growth and fruit enlargement under continuous chilling night temperature to develop new cultivars tolerant to chilling temperature. Two cultivars expected to have chilling tolerance and another cultivar sensitive to chilling temperature were grown in greenhouses with chilling and optimal night temperature conditions. In the early growth stage after transplanting, the cultivars expected to have chilling tolerance showed better vine length, fresh weight and dry weight. However, one of the tolerant cultivars showed significantly lower vine length, leaf length and width, and petiole length than the sensitive cultivar during pollination period and later growth stage, showing genotype specific responses. The fruit length, width, and weight were also significantly lower in the tolerant cultivar. The fruit set ratio was significantly higher in the chilling sensitive cultivar than the two tolerant cultivars. These results suggest that the present chilling tolerant cultivars in watermelon were selected based on their performance in the early growth stage, and further studies on chilling tolerance in different growth and development stages are required to develop cultivars adapted to various forcing cultivation systems.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.1
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• pp.1-8
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• 2017

Given a multi-dimensional dataset of tuples, a skyline query returns a subset of tuples which are not 'dominated' by any other tuples. Skyline query is very useful in Big data analysis since it filters out uninteresting items. Much interest was devoted to the MapReduce-based parallel processing of skyline queries in large-scale distributed environment. There are three requirements to improve parallelism in MapReduced-based algorithms: (1) workload should be well balanced (2) avoid redundant computations (3) Optimize network communication cost. In this paper, we introduce MR-SEAP (MapReduce sample Skyline object Equality Angular Partitioning), an efficient angular space partitioning based skyline query processing using sampling-based pruning, which satisfies requirements above. We conduct an extensive experiment to evaluate MR-SEAP.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.5
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• pp.209-220
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• 2013

Handover is the technology to minimize data lose of mobile devices and make continuous communication possible even if the device could be moved from one digital cell site to another one. That is, it is a function that enables the mobile user to avoid the disconnection of phone conversations when moving from a specific mobile communication area to another. Today, there are a lot of ongoing researches for fast and efficient hand-over, in order to address phone call's delay and disconnection which are believed to be the mobile network's biggest problems, and these should essentially be resolved in all mobile networks. Thanks to recent technology development in mobile network, the LTE network has been commercialized today and it has finally opened a new era that makes it possible for mobile phones to process data at high speed. In LTE network environment, however, a new authentication key must be generated for the hand-over. In this case, there can be a problem that the authentication process conducted by the hand-over incurs its authentication cost and delay time. This essay suggests an efficient key caching hand-over method which simplifies the authentication process: when UE makes hand-over from oMME to nMME, the oMME keeps the authentication key for a period of time, and if it returns to the previous MME within the key's lifetime, the saved key can be re-used.

• Journal of Intelligence and Information Systems
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• v.26 no.1
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• pp.119-133
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• 2020

Fama asserted that in an efficient market, we can't make a trading rule that consistently outperforms the average stock market returns. This study aims to suggest a machine learning algorithm to improve the trading performance of an intraday short volatility strategy applying asymmetric volatility spillover effect, and analyze its trading performance improvement. Generally stock market volatility has a negative relation with stock market return and the Korean stock market volatility is influenced by the US stock market volatility. This volatility spillover effect is asymmetric. The asymmetric volatility spillover effect refers to the phenomenon that the US stock market volatility up and down differently influence the next day's volatility of the Korean stock market. We collected the S&P 500 index, VIX, KOSPI 200 index, and V-KOSPI 200 from 2008 to 2018. We found the negative relation between the S&P 500 and VIX, and the KOSPI 200 and V-KOSPI 200. We also documented the strong volatility spillover effect from the VIX to the V-KOSPI 200. Interestingly, the asymmetric volatility spillover was also found. Whereas the VIX up is fully reflected in the opening volatility of the V-KOSPI 200, the VIX down influences partially in the opening volatility and its influence lasts to the Korean market close. If the stock market is efficient, there is no reason why there exists the asymmetric volatility spillover effect. It is a counter example of the efficient market hypothesis. To utilize this type of anomalous volatility spillover pattern, we analyzed the intraday volatility selling strategy. This strategy sells short the Korean volatility market in the morning after the US stock market volatility closes down and takes no position in the volatility market after the VIX closes up. It produced profit every year between 2008 and 2018 and the percent profitable is 68%. The trading performance showed the higher average annual return of 129% relative to the benchmark average annual return of 33%. The maximum draw down, MDD, is -41%, which is lower than that of benchmark -101%. The Sharpe ratio 0.32 of SVS strategy is much greater than the Sharpe ratio 0.08 of the Benchmark strategy. The Sharpe ratio simultaneously considers return and risk and is calculated as return divided by risk. Therefore, high Sharpe ratio means high performance when comparing different strategies with different risk and return structure. Real world trading gives rise to the trading costs including brokerage cost and slippage cost. When the trading cost is considered, the performance difference between 76% and -10% average annual returns becomes clear. To improve the performance of the suggested volatility trading strategy, we used the well-known SVM algorithm. Input variables include the VIX close to close return at day t-1, the VIX open to close return at day t-1, the VK open return at day t, and output is the up and down classification of the VK open to close return at day t. The training period is from 2008 to 2014 and the testing period is from 2015 to 2018. The kernel functions are linear function, radial basis function, and polynomial function. We suggested the modified-short volatility strategy that sells the VK in the morning when the SVM output is Down and takes no position when the SVM output is Up. The trading performance was remarkably improved. The 5-year testing period trading results of the m-SVS strategy showed very high profit and low risk relative to the benchmark SVS strategy. The annual return of the m-SVS strategy is 123% and it is higher than that of SVS strategy. The risk factor, MDD, was also significantly improved from -41% to -29%.

• KDI Journal of Economic Policy
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• v.14 no.2
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• pp.109-153
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• 1992

This paper estimates a translog cost function for the Korea's banking industry and derives various implications on the prospect for the Korean banking structure in the future based on the estimated efficiency indicators for the banking sector. The Korean banking industry is permitted to operate trust business to the full extent and the security business to a limited extent, while it is formally subjected to the strict, specialized banking system. Security underwriting and investment businesses are allowed in a very limited extent only for stocks and bonds of maturity longer than three year and only up to 100 percent of the bank paid-in capital. Until the end of 1991, the ceiling was only up to 25 percent of the total balance of the demand deposits. However, they are prohibited from the security brokerage business. While the in-house integration of security businesses with the traditional business of deposit and commercial lending is restrictively regulated as such, Korean banks can enter the security business by establishing subsidiaries in the industry. This paper, therefore, estimates the efficiency indicators as well as the cost functions, identifying the in-house integrated trust business and security investment business as important banking activities, for various cases where both the production and the intermediation function approaches in modelling the financial intermediaries are separately applied, and the banking businesses of deposit, lending and security investment as one group and the trust businesses as another group are separately and integrally analyzed. The estimation results of the efficiency indicators for various cases are summarized in Table 1 and Table 2. First, security businesses exhibit economies of scale but also economies of scope with traditional banking activities, which implies that in-house integration of the banking and security businesses may not be a nonoptimal banking structure. Therefore, this result further implies that the transformation of Korea's banking system from the current, specialized system to the universal banking system will not impede the improvement of the banking industry's efficiency. Second, the lending businesses turn out to be subjected to diseconomies of scale, while exhibiting unclear evidence for economies of scope. In sum, it implies potential efficiency gain of the continued in-house integration of the lending activity. Third, the continued integration of the trust businesses seems to contribute to improving the efficiency of the banking businesses, since the trust businesses exhibit economies of scope. Fourth, deposit services and fee-based activities, such as foreign exchange and credit card businesses, exhibit economies of scale but constant returns to scope, which implies, the possibility of separating those businesses from other banking and trust activities. The recent trend of the credit card business being operated separately from other banking activities by an independent identity in Korea as well as in the global banking market seems to be consistent with this finding. Then, how can the possibility of separating deposit services from the remaining activities be interpreted? If one insists a strict definition of commercial banking that is confined to deposit and commercial lending activities, separating the deposit service will suggest a resolution or a disappearance of banking, itself. Recently, however, there has been a suggestion that separating banks' deposit and lending activities by allowing a depository institution which specialize in deposit taking and investing deposit fund only in the safest securities such as government securities to administer the deposit activity will alleviate the risk of a bank run. This method, in turn, will help improve the safety of the payment system (Robert E. Litan, What should Banks Do? Washington, D.C., The Brookings Institution, 1987). In this context, the possibility of separating the deposit activity will imply that a new type of depository institution will arise naturally without contradicting the efficiency of the banking businesses, as the size of the banking market grows in the future. Moreover, it is also interesting to see additional evidences confirming this statement that deposit taking and security business are cost complementarity but deposit taking and lending businesses are cost substitute (see Table 2 for cost complementarity relationship in Korea's banking industry). Finally, it has been observed that the Korea's banking industry is lacking in the characteristics of natural monopoly. Therefore, it may not be optimal to encourage the merger and acquisition in the banking industry only for the purpose of improving the efficiency.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.5
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• pp.670-677
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• 2004

Sixteen multiparous Holstein-Friesian crossbred cows in mid-lactation were blocked according to days in milk (DIM) and previous lactation and randomly assigned according to a Randomized Complete Block (RCB) design with four replications to receive four dietary treatments. The dietary treatments consisted of T1: No cassava hay (CH) or stylo 184 hay (SH) supplementation, supplementation of concentrate to milk yield at 1:2 (control), T2: Supplementation of 1 kg of CH/hd/d, supplementation of concentrate to milk yield at 1:2, T3: Supplementation of 1 kg of CH+SH/hd/d, supplementation of concentrate to milk yield at 1:2, T4: Supplementation of 2 kg of CH+SH/hd/d, supplementation of concentrate to milk yield at 1:3. All animals received Ruzi grass from a cut-and-carry system as roughage source. The feeding trial lasted for 9 weeks. The results revealed that DMI of concentrate of supplemented treatments were significantly lower (p<0.05) than those in the control, but there was no significant difference between T2 and T3. There was no significant difference in forage DM intake between the control and supplemented treatments. CP and NDF digestibility of supplemented treatments were significantly (p<0.05) greater than the control and there were no significant differences among supplemented treatments. Milk yield and 3.5% FCM (14.3, 14.5, 14.7 and 14.8; 13.9, 14.3, 14.3 and 14.6 kg/hd/d, respectively) were not significantly different among treatments. Milk protein percentage of supplemented treatments was significantly (p<0.05) higher than the control, but there were no significant differences among supplemented treatments. There was no significant difference in milk fat percentage between the control and supplemented treatments. However, milk fat percentage tended to be higher for supplemented animals as compared to the control group. There were also no significant differences in lactose, solids-not-fat and total solids percentages among treatments. Cows in supplemented treatments gave incomes over supplement cost (IOSC) of 2.72, 2.74 and 2.93 US$/hd/d, respectively which were greater than for cows on control treatment. Furthermore, IOSC were greatest for cows in T4 as compared to other treatments. Based on this study it was concluded that, feeding cassava hay solely or in combination with stylo 184 hay as a supplemental protein source could be a potential valuable strategy in small-holder dairy farming systems in the tropics. This strategic supplementation significantly reduced concentrate use, which resulted in improved milk yields and milk quality for the supplemented cows. Moreover, it resulted in higher economical returns through increased productivity and lower ratios of concentrate to milk yield, from 1:2 to 1:3.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.3
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• pp.63-72
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• 2010

This study was conducted to investigate the current status and the improvement plans of the ecosystem conservation fund return projects. In 2007, there was a reformation of the ecosystem conservation fund system but the fund return projects were not vitalized up until now. In this study, 35 of ongoing and finished fund return projects were investigated on their types, sites, costs, local governments, and time required to return the fund. Through the on-site survey of 9 finished projects (4 biotope, 2 corridor and 3 natural conservation facility projects), construction and management conditions were investigated. The main findings are as follows: Among the five fund return types, 17 cases were biotope restoration projects, 4 cases were ecological corridor projects, and 1 case was a nature replacement project. In the case of project sites, there were 14 cases near schools and public facilities, 8 cases near rivers or streams, and 2 cases near ponds or wetlands. For the construction costs, there were 19 cases (65% of all the projects) that cost less than 300 million won. In terms of the involvement of the local government, most of the fund return projects were concentrated in Gyeonggi province and Ulsan city, and there were some local governments outside of these regions that did not carry out any return projects at all. Lastly, in the case of fund return time required, 35% of the fund returns were completed within 5 months, but the overall average fund return time was 9.8 months. In respond to the above study results, the improvement plans to encourage fund return projects are as follows: To diversify return types and sites, piloting and modeling projects for the representative types and sites should be preceded. To emerge from customary small-scaled projects, incentives to encourage large-scale and ecological networking projects should be considered. In addition, in order to write up business plans for the fund return projects, long-term investigations of at least 2 seasons from spring to fall are necessary. Finally, for the continuous management and maintenance of the ecological fund return sites, easier way for the citizens to actively participate in the projects should be incorporated.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.12
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• pp.1749-1754
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• 2003

The study was undertaken to see the effect of elevated feeding during pre-partum or pre- as well as post-partum period on the productive and reproductive performance of crossbred cows. The experiment lasted for 60 d pre-partum to 120 d post-partum. Eighteen dry pregnant crossbred cows divided into three equal groups were fed either as per NRC feeding standard (C) or 20% above NRC during 60 d pre-partum ($T_1$) or fed 20% above NRC during both 60 d pre-partum to 120 d post-partum ($T_2$) period. During prepartum period body weight gain was significantly ($p{\leq}0.05$) higher in $T_1$ and $T_2$ groups than that of control group. The animals fed at higher plane of nutrition ($T_1$ and $T_2$) took significantly lesser time for complete relaxation of pelvic muscles, act of calving and for expulsion of placenta than that of control group. Moreover, such cows delivered 2 to 3 kg heavier calves as compared to normal fed dams. During post-partum period, the average daily milk yield was significantly higher in $T_2$ group than that in $T_1$ and control groups. The peak yield was significantly higher in $T_2$ group, it took longer time to reach peak production but it was more persistent in this group as compared to $T_1$ and control groups. Average milk fat, solids-not-fat (SNF) and total solids were significantly higher in $T_1$ and $T_2$ groups as compared to control group. Body weight losses incurred during early lactation were not even compensated by end of 4th month of lactation in C and $T_1$ groups whereas the animals in $T_2$ group gained 2.0 kg. The 1st post-partum estrus and conception rate were better in high fed groups ($T_1$ and $T_2$) than that of control group. The returns over feed cost of milk production were higher in $T_2$ group followed by $T_1$ and control groups indicating the advantage of elevated feeding during pre- and post-partum periods.

• Science of Emotion and Sensibility
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• v.23 no.1
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• pp.3-16
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• 2020

Recently, as the fashion e-commerce market has expanded, the proportion of online shops that are growing rapidly has increased and with them so too has competition. Most retailers operating online shops need their own competitiveness, and accordingly, the need to develop their logistics service quality components is increasing. This study investigated the quality of the logistics services, which is a factor of the logistics service quality of the internet shop. It influences customer satisfaction and repurchase intention by collecting samples from the customers using online fashion shops. Two hundred customers who shop online were surveyed to extract the data. The sample was subjected to basic statistical analysis using the SPSS 25.0 package, and factor analysis, t-test, ANOVA, and correlation analysis were performed. The results of this study showed that the information quality of proactive return, promptness of the return process, and reliability of the return cost had a positive impact on customer satisfaction, and it had a significant influence on the customer's repurchase intention to the online store. A selection of shops showed high amounts of return reasons, high customer satisfaction, and high repurchase, whereas, in general, many others scored poorly across these criteria. This suggests that a retailer operating online should consider pages for receiving information plus sales content in addition to the quality and constituent factors of its logistics services for returns that influence repurchase and satisfaction.

• KIPS Transactions on Software and Data Engineering
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• v.1 no.2
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• pp.127-136
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• 2012

Many research of hand gesture recognition based on vision system have been conducted which enable user operate various electronic devices more easily. 3D position calculation and meaningful gesture classification from similar gestures should be executed to recognize hand gesture accurately. A simple and cost effective method of 3D position calculation and gesture spotting (a task to recognize meaningful gesture from other similar meaningless gestures) is described in this paper. 3D position is achieved by calculation of two cameras relative position through pan/tilt module and a marker regardless with the placed position. Fuzzy garbage model is proposed to provide a variable reference value to decide whether the user gesture is the command gesture or not. The reference is achieved from fuzzy command gesture model and fuzzy garbage model which returns the score that shows the degree of belonging to command gesture and garbage gesture respectively. Two-stage user adaptation is proposed that off-line (batch) adaptation for inter-personal difference and on-line (incremental) adaptation for intra-difference to enhance the performance. Experiment is conducted for 5 different users. The recognition rate of command (discriminate command gesture) is more than 95% when only one command like meaningless gesture exists and more than 85% when the command is mixed with many other similar gestures.