• Korean Journal of Agricultural Science
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• v.29 no.1
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• pp.66-83
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• 2002

The economic feasibility analysis including benefit-cost ratio and internal rate of return of a land consolidation and on-farm development project was mainly depended upon the direct benefits and costs arising during project life. Therefore the projects were neglected in allocating the government's financial funds and loans on account of the low economic rate of return of the project. Accordingly the extended benefit-cost analysis method should be introduced and adapted to cover not only the benefit s such as non-market values of environmental and food security fun ct ions of the project but also market values of the project outputs. The main purposes of this study are (1) to prepare a guide line for economic feasibility analysis based on the IBRD and ADB guidelines, (2) to estimate the benefits from productivity increase, labor saving, savings of O&M cost of farm mechanization and project facilities, savings of farmer's burden for their public health, increasing environmental and public functional value of paddy fields, improving food security condition and formation of peaceful and uncontroversial rural society by implementing the land consolidation and on-farm development, (3) to introduce the newly adapted analytical method as the extended benefit cost analysis which could make possible to be included the values of non-market goods such as the food security and the environmental public function of paddy fields. To carry out this study, the existing publications on the guidelines for economic agricultural projects were reviewed and consultation was made with a For the post evaluation study of the land consolidation and on-farm development project, field survey in Jigok and other comparative area were made to get available information. According to the project completion report, Jigok land consolidation and on-farm development project has 55ha of benefit area out of 69ha of gross area. The project was started in November 11th, 2000 and completed october 30th, 2001. The total project costs were amounted to 2,548 million won and the annual project benefits were estimated at 335million won evaluated by domestic market prices. The ERR(Economic Rate of Return) and SRR(Social Rate of Return) of the project based on the shadow pricing system were estimated at 4.4% and 16% respectively. On the other hand, the ERR and SRR based on the domestic market value system were amounted to 6.37% and 14.62%. In conclusion, Korean land consolidation and on-farm development projects have not carried out from the view point of economic rate of return under shadow pricing system but from the view point of domestic pricing system. For the future feasibility studies on land consolidation projects have to be carried out including the non-market values as environmental and food security function of the projects.

• The Journal of Information Systems
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• v.27 no.3
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• pp.43-62
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• 2018

Purpose Since the Bitcoin, which was the first virtual currency, was made at 2009, almost 1,000 virtual currencies appeared onstage in the world. Even though virtual currencies have the function of money as a medium of exchange or contract, any of those has not yet entered the commercialization stage. Instead, some of the virtual currencies show the nature of investment assets. In the case of virtual money investment, users tend to use all the information of the world because information transfer is very easy and capital movement is almost free between different countries. In addition, as the transaction sizes of virtual currencies increase, a virtual currency price is no longer independent and is likely to be affected by the prices of other virtual currencies. Therefore, it is necessary to understand the influence among virtual currency markets, which helps successful implementation of investment strategies. Design/methodology/approach This study focuses on the investment product function of virtual money and conducts the analysis using the time series model used in the financial and economic areas. In this paper, we try to analyze the return and volatility transfer effect of virtual money markets through GJR-GARCH model. Findings This study is expected to find out whether we can make market forecasts through reflecting changes in other markets. In addition, we can reduce the trial and error of user decision making by using the information on the yield and volatility transition effect derived from the research results, and it is expected to reduce the opportunity cost of users.

• Clinics in Shoulder and Elbow
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• v.26 no.1
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• pp.64-70
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• 2023

Background: This study aimed to analyze the efficacy of single-dose corticosteroid injection (CSI) administered at 6 weeks postoperative to treat stiffness following arthroscopic rotator cuff repair (ARCR). Methods: In this prospective, multicentric, case-control study, post-ARCR stiffness at 6 weeks was treated with either a single dose of intra-articular CSI (CSI group) or physical therapy with oral analgesics (non-CSI group). Pain intensity according to visual analog scale (VAS), functional outcome using the Constant Murley Shoulder Score, time to return to activities of daily living (ADLs), and retear rate were recorded at 6 weeks, 9 weeks, 12 weeks, 6 months, 12 months, and 18 months postoperatively in both groups. Results: A total of 149 patients (54.5%) in the CSI group and 124 patients (45.5%) in the non-CSI group were included in this study. Pain and function were significantly better in the CSI group at 9-week, 12-week, and 6-month (P<0.001) follow-up, whereas they were not significantly different when the groups were compared at 12- and 18-month follow-up. The mean duration to return to ADLs was significantly shorter (P<0.001) in the CSI group. The incidence of retears was not significantly different (P=0.36) between groups at the end of 18 months of follow-up. Conclusions: Single-dose intra-articular CSI administered at 6 weeks postoperative to treat post-ARCR stiffness significantly improved pain, function, and duration of return to ADLs without increasing the risk of retears compared to patients who did not receive intra-articular CSI. Level of evidence: III.

• Korean Journal of Radiology
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• v.22 no.5
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• pp.759-769
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• 2021

Objective: To evaluate the application of laplacian-regularized mean apparent propagator (MAPL)-MRI to brain glioma-induced corticospinal tract (CST) injury. Materials and Methods: This study included 20 patients with glioma adjacent to the CST pathway who had undergone structural and diffusion MRI. The entire CSTs of the affected and healthy sides were reconstructed, and the peritumoral CSTs were manually segmented. The morphological characteristics of the CST (track number, average length, volume, displacement of the affected CST) were examined and the diffusion parameter values, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), mean squared displacement (MSD), q-space inverse variance (QIV), return-to-origin probability (RTOP), return-to-axis probabilities (RTAP), and return-to-plane probabilities (RTPP) along the entire and peritumoral CSTs, were calculated. The entire and peritumoral CST characteristics of the affected and healthy sides as well as those relative CST characteristics of the patients with motor weakness and normal motor function were compared. Results: The track number, volume, MD, RD, MSD, QIV, RTAP, RTOP, and RTPP of the entire and peritumoral CSTs changed significantly for the affected side, whereas the AD and FA changed significantly only in the peritumoral CST (p < 0.05). In patients with motor weakness, the relative MSD of the entire CST, QIV of the entire and peritumoral CSTs, and the AD, MD, RD of the peritumoral CST were significantly higher, whereas the RTPP of the entire and peritumoral CSTs and the RTOP of the peritumoral CST were significantly lower than those in patients with normal motor function (p < 0.05 for all). In contrast, no significant changes were found in the CST morphological characteristics, FA, or RTAP (p > 0.05 for all). Conclusion: MAPL-MRI is an effective approach for evaluating microstructural changes after CST injury. Its sensitivity may improve when using the peritumoral CST features.

• 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%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.620-628
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• 1997

When the Chebyshev function is applied to design the waveguide transition, it exhibits poor impedance matching characteristics due to impedance discontinuities at the ends of tapered line. In this paper, an improved Chebyshev function, which is obtained by using the convolution property, is proposed to make improvements on the impedance matching characteristics of the waveguide transition. When rectangular to circular waveguide transition is designed by improved function, then the computed return loss is approximately 5 dB better than the conventional Chebyshev function.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.1
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• pp.145-152
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• 1996

In this study, the technique to evaluate the extreme design wave height of certain return period is developed from the given measured or hindcasted sea state data of concerned area for limited period. By using the order statistics and Monte Carlo Simulation method, the best fit probability distribution function with proper parameters describing the given wave height data is chosen, from which extreme design wave height can be predicted by extrapolation to the desired return period. The fitness and the confidence limit of the chosen probability function are also discussed. Application calculation is carried out for the wave height data given by applying the Wilson wave model theory to major 50 typhoon wind data affecting Korean South coast during the year from 1938 to 1987.

• ETRI Journal
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• v.33 no.6
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• pp.897-903
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• 2011

A hybrid ${\Delta}{\Sigma}$ modulator for audio applications is presented in this paper. The pulse generator for digital-to-analog converter alleviates the requirement of the external clock jitter and calibrates the coefficient variation due to a process shift and temperature changes. The input resistor network in the first integrator offers a gain control function in a dB-linear fashion. Also, careful chopper stabilization implementation using return-to-zero scheme in the first continuous-time integrator minimizes both the influence of flicker noise and inflow noise due to chopping. The chip is implemented in a 0.13 ${\mu}m$ CMOS technology (I/O devices) and occupies an active area of 0.37 $mm^2$. The ${\Delta}{\Sigma}$ modulator achieves a dynamic range (A-weighted) of 97.8 dB and a peak signal-to-noise-plus-distortion ratio of 90.0 dB over an audio bandwidth of 20 kHz with a 4.4 mW power consumption from 3.3 V. Also, the gain of the modulator is controlled from -9.5 dB to 8.5 dB, and the performance of the modulator is maintained up to 5 nsRMS external clock jitter.

• The KIPS Transactions:PartC
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• v.12C no.3 s.99
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• pp.323-330
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• 2005

Buffer overflow is one of the most prevalent and critical internet security vulnerabilities. Recently, various methods to prevent buffer overflow attacks have been investigated, but they are still difficult to apply to real applications due to their run-time overhead. This paper suggests an efficient rewrite method to prevent buffer-overflow attacks only with lower costs by generating a redundant copy of the return address in stack frame and comparing return address to copied return address. Not to be overwritten by the attack data the new copy will have the lower address number than local buffers have. In addition, for a safer execution environment, every vulnerable function call is transformed during the rewriting procedure.

• Journal of Engineering Education Research
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• v.27 no.1
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• pp.50-62
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• 2024

This study examined how emotion regulation strategies specifically function in the interpersonal conflict coping strategies of engineering students. For this purpose, a interpersonal conflict coping strategies and emotion regulation strategies scale was used for 548 engineering students. Multiple regression analysis was conducted. Among the emotion regulation strategies, the "return to body" strategy was related to understanding, validation, focusing, and the "stop action" strategy. In particular, the "stop action" strategy was closely related only to the "return to body" strategy. Among interpersonal conflict coping strategies, the dominating strategy used both positive emotion regulation strategies, such as high refocus on planning, and negative emotion regulation strategies, such as other-blame. Additionally, among negative conflict coping strategies, it was confirmed that both aggression and negative emotional expression, which seem to have similar attributes, share a common feature of having high difficulty in emotional clarity. However, in the case of negative emotional expression, it is characterized by a lack of putting into perspective and high other-blame. On the other hand, the agression strategy seemed to have different characteristics, such as high self-blame and low return to body. By investigating the relationship between interpersonal conflict coping strategies and specific emotion regulation strategies, this study provides implications for education and intervention on which specific emotion regulation strategies need to be cultivated for engineering students to improve their interpersonal conflict resolution capabilities.