• Asian Journal of Innovation and Policy
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• v.7 no.1
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• pp.178-189
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• 2018

In this paper, we present a case study of a new emerging business startup involved in smart house appliances. The irreversible investment concept and real-option theory are introduced as the fundamentals of the model. By using games theory we show that the startup's actions can trigger reactions from other firms. The first part covers initial the research and development stage, while the second part covers production and commercialization. The findings of this study suggest that, given a certain amount of initial investment, an open and shared innovation may lead to hurting a firm's investment while strengthening the competitors' position in the market. However, given the sensitivity analysis, when volatility and demand grow favorably, sharing R&D investment is not a bad option for a new player to adjust its position in the market while still maintaining positive returns.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.9
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• pp.690-700
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• 2013

This study reviewed how the changes of the government policy on solar power generation projects affected the annual mandatory quotas of the regulated power providers under the RPS (renewable portfolio standard) system and analysed economic feasibility of the investment for meeting their quotas as compared to the case of non-regulated power providers. The analysis results showed that under the discount rate of 7.5%, which was used for the annual national electricity plans for the recent years, both the regulated and non-regulated power providers achieved economic feasibility under both the NPV (net present value) method and the real option pricing method. It was also shown that higher profitability was attained by non-regulated power providers than by their regulated counterparts, which can be attributable to the fact that regulated providers are required to out-source 50% of the total quota. The results of this study are considered to be useful for establishing a meaningful mid term or long term strategy for the future of solar power generation linked to the current RPS system.

• Journal of the Korean Data and Information Science Society
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• v.19 no.4
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• pp.1305-1325
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• 2008

As index option markets grow recently, many analysts and investors become interested in forecasting the volatility of KOSPI 200 Index to achieve portfolio's goal from the point of financial risk management and asset evaluation. To serve this purpose, we introduce NN and SVM integrated with other financial series models such as GARCH, EGARCH, and EWMA. Moreover, according to the empirical test, Integrating NN with GARCH or EWMA models improves prediction power in terms of the precision and the direction of the volatility of KOSPI 200 index. However, integrating SVM with financial series models doesn't improve greatly the prediction power. In summary, SVM-EGARCH was the best in terms of predicting the direction of the volatility and NN-GARCH was the best in terms of the prediction precision. We conclude with advantages of the integration process and the need for integrating models to enhance the prediction power.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.1
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• pp.37-42
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• 2015

Aggressive benign odontogenic neoplasms have substantial potential to grow to an enormous size with resulting bone deformities, and they often invade adjacent tissues and spread beyond their normal clinical and radiographic margins; as such, they have a high rate of recurrence. Historically, management (conservative versus aggressive) on the basis of clinical, radiographic and/or histopathologic characteristics has been controversial. However, recent advances in the understanding of the biological features of these lesions may provide greater evidence of the benefits of conservative management. Three patients with different complaints and final histopathologic diagnoses were enrolled in the study. All three cases were treated by a single operator with similar conservative surgical procedures. During follow-up, the patients had uneventful secondary healing and bone regeneration, less packing time than previously reported, no clinical or radiographic evidence of recurrence and no apparent deformity. The aggressive behavior of these lesions requires long clinical and radiographic follow-up. Conservative surgical management may be an option to reduce recurrence and morbidity and increase the probability of uneventful secondary healing and bone regeneration.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.5
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• pp.703-715
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• 2015

One of the challenges to increase milk production in a large pasture-based herd with an automatic milking system (AMS) is to grow forages within a 1- km radius, as increases in walking distance increases milking interval and reduces yield. The main objective of this study was to explore sustainable forage option technologies that can supply high amount of grazeable forages for AMS herds using the Agricultural Production Systems Simulator (APSIM) model. Three different basic simulation scenarios (with irrigation) were carried out using forage crops (namely maize, soybean and sorghum) for the spring-summer period. Subsequent crops in the three scenarios were forage rape over-sown with ryegrass. Each individual simulation was run using actual climatic records for the period from 1900 to 2010. Simulated highest forage yields in maize, soybean and sorghum- (each followed by forage rape-ryegrass) based rotations were 28.2, 22.9, and 19.3 t dry matter/ha, respectively. The simulations suggested that the irrigation requirement could increase by up to 18%, 16%, and 17% respectively in those rotations in El-Nino years compared to neutral years. On the other hand, irrigation requirement could increase by up to 25%, 23%, and 32% in maize, soybean and sorghum based rotations in El-Nino years compared to La-Nina years. However, irrigation requirement could decrease by up to 8%, 7%, and 13% in maize, soybean and sorghum based rotations in La-Nina years compared to neutral years. The major implication of this study is that APSIM models have potentials in devising preferred forage options to maximise grazeable forage yield which may create the opportunity to grow more forage in small areas around the AMS which in turn will minimise walking distance and milking interval and thus increase milk production. Our analyses also suggest that simulation analysis may provide decision support during climatic uncertainty.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.557-562
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• 2005

The field scale experiment was performed to examine the effect of plant coverage on the constructed wetland performance and recommend the optimum development and management of macrophyte communities. Four sets(each set of 0.88ha) of wetland (0.8ha) and pond(0.08ha) systems were used. Water flowing into the Seokmoon estuarine reservoir from the Dangjin stream was pumped into wetland system. Water depth was maintained at $0.3{\sim}0.5m$ and hydraulic retention time was managed to about $2{\sim}5$ days; emergent plants were allowed to grow in the wetlands. After three growing seasons of the construction of wetlands, plant coverage was about 95%, even with no plantation, from bare soil surfaces at the initial stage. Dead vegetation affected nitrogen removal during winter because it is a source of organic carbon which is an essential parameter in denitrification. Biomass harvesting is not a realistic management option for most constructed wetland systems because it could only slightly increase the removal rate and provide a minor nitrogen removal pathway due to lack of organic carbon.

• Journal of Korean Neurosurgical Society
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• v.51 no.3
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• pp.155-159
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• 2012

The treatment of bilateral vertebral artery dissecting aneurysms (VADAs) presenting with subarachnoid hemorrhage (SAH) is still challenging. The authors report a rare case of bilateral VADA treated with coil trapping of ruptured VADA and covered stents implantation after multiple unsuccessful stent assisted coiling of the contralateral unruptured VADA. A 44-year-old woman was admitted to our hospital because of severe headache and sudden stuporous consciousness. Brain CT showed thick SAH and intraventricular hemorrhage. Cerebral angiography demonstrated bilateral VADA. Based on the SAH pattern and aneurysm configurations, the right VADA was considered ruptured. This was trapped with endovascular coils without difficulty. One month later, the contralateral unruptured VADA was protected using a stent-within-a-stent technique, but marked enlargement of the left VADA was detected by 8-months follow-up angiography. Subsequently two times coil packing for pseudosacs resulted in near complete occlusion of left VADA. However, it continued to grow. Covered stents graft below the posterior inferior cerebellar artery (PICA) origin and a coronary stent implantation across the origin of the PICA resulted in near complete obliteration of the VADA. Covered stent graft can be used as a last therapeutic option for the management of VADA, which requires absolute preservation of VA flow.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.148-164
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• 2017

The focus on the issues surrounding spent nuclear fuel and lifetime extension of old nuclear power plants continues to grow nowadays. A transparent decision-making process to identify the best suitable nuclear fuel cycle (NFC) is considered to be the key task in the current situation. Through this study, an attempt is made to develop an equilibrium model for the NFC to calculate the material flows based on 1 TWh of electricity production, and to perform integrated multicriteria decision-making method analyses via the analytic hierarchy process technique for order of preference by similarity to ideal solution, preference ranking organization method for enrichment evaluation, and multiattribute utility theory methods. This comparative study is aimed at screening and ranking the three selected NFC options against five aspects: sustainability, environmental friendliness, economics, proliferation resistance, and technical feasibility. The selected fuel cycle options include pressurized water reactor (PWR) once-through cycle, PWR mixed oxide cycle, or pyroprocessing sodium-cooled fast reactor cycle. A sensitivity analysis was performed to prove the robustness of the results and explore the influence of criteria on the obtained ranking. As a result of the comparative analysis, the pyroprocessing sodium-cooled fast reactor cycle is determined to be the most competitive option among the NFC scenarios.

• Journal of Climate Change Research
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• v.8 no.2
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• pp.91-97
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• 2017

Korean solar energy companies are currently suffering bankruptcy, receivership, liquidation of operation, lay-off or other similar event and most of the conglomerate are also downsized or discontinued operations in the industry. This study aims to assist Korean solar energy companies in making decision to overcome the current industrial crisis through looking into the Korean companies' growth, encounter with the crisis and strategies to survive. The main research topic in this study is a comparison between respective effect of M&A and restructuring on corporate value to understand such effects on solar energy companies. In this study, we utilized a variety of research methodologies, including dummy regression analysis, binary analysis of variance, analysis of cross addition to T-test was carried out empirical analysis. As a result, it seems that the companies who chose an M&A are facing a better situation in terms of survival and market share despite the ongoing crisis. Through this study, it could be found that, for a technology company, an M&A would be a better option than restructuring to grow and overcome a crisis.

• Journal of Korean Society on Water Environment
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• v.37 no.1
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• pp.47-54
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• 2021

Aerobic granular sludge (AGS) can be classified as a type of self-immobilized microbial aggregates measuring more than 0.2 mm. It offers the option to simultaneously remove COD, N, and P that occur in different zones inside a granule. Also, AGS is characterized by high precipitability, treatability with high organic loading, and high tolerance to low temperature. In this study, a sequencing batch reactor inoculated with AGS (AGS-SBR) is a new advanced wastewater treatment process that was proven to grow AGS with integrated nutrient removal and low C/N ratio. A pilot plant, AGS-SBR with a capacity of 225 ㎥/d was installed at an S sewage treatment plant in Gyeonggi-do. The results of the operation showed that the water quality of the effluent indicated that the value of BOD5 was 1.5 mg/L, CODMn was 11.4 mg/L, SS was 6.2 mg/L, T-N was 13.2 mg/L, and T-P was 0.197 mg/L, and all of these values reliably satisfied an effluent standard (I Area). In winter, the T-N treatment efficiency at a lower temperature of less than 11℃ also showed reliability to meet the effluent standard of the I Area (20 mg/L or less). Analysis of microbial community in AGS showed a higher preponderance of beneficial microorganisms involved in denitrification and phosphorus accumulation compared with activated sludge. The power consumption and sludge disposal cost were reduced by 34.7% and 54.9%, respectively, compared to the domestic SBR type sewage treatment plant with a processing capacity of 1,000 ㎥/d or less.