• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.57 no.1
• /
• pp.69-78
• /
• 2024

We have proposed a method for estimating the size-dependent mortality (M) of short-lived semelparous cephalopod species. To estimate the size-dependent mortality of a winter cohort of the common squid Todarodes pacificus, a commercially important cephalopod species in the North Pacific, we used the data and results of previous studies. On the basis of the bigger-is-better the steady-state hypothesis, we derived a theoretical mortality curve by assuming M as an inverse function of mantle length (ML). The derived constant for size-specific instantaneous mortality (q), assuming an embryonic survival rate of 86.6%, was 0.413 day^-1 mm in ML. Estimates of life-stage-specific M ranged from 0.0280 to 0.435 day^-1 for paralarvae, 0.00278 to 0.0269 day^-1 for juveniles, 0.00197 to 0.00275 day^-1 for pre-spawning adults, and 0.0913 to 0.0920 day^-1 for post-spawning adults. Sensitivity analyses showed that the derived size-dependent M did not significantly change with varying embryonic survival rates, from 48%, the lowest reported value, to 100%. Additionally, comparison of the length frequencies derived from our simulations with those derived from catch data did not show a significant difference, suggesting that our approach and procedures are reliable for stock assessment and management of the common squid.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.25 no.4
• /
• pp.59-76
• /
• 2023

The COVID-19 pandemic has brought about environmental severity and new social, economic, and cultural changes. Conscious fashion, which is oriented to sustainable and valuable consumption, has become a trend to consume products produced using eco-friendly and ethical processes, from the selection of the product materials to the manufacturing process. The purpose of this study is to identify the concepts and characteristics of conscious fashion and zero waste, and to explore design trends of zero wastein the new normal era of conscious fashion through the analysis of various cases. The research method is a literature review on conscious fashion based on relevant professional and academic books and articles, designer collections, and campaigns from 2010 to the present, when conscious fashion as eco-friendliness and sustainable fashion became a trend. The concept and characteristics of conscious fashion were examined them in terms of environmental, ethical, social, and cultural aspects and the concept and characteristics of zero waste through previous studies and case analysis. Through this, the trends of zero-waste design in conscious fashion were categorized into: first, an eco-friendly design orientation that utilizes reuse and reduce methods of clothing and fabric; second, a variable design orientation that practices zero waste designs by using diversity of patterns through deconstruction, disassembly, and various cutting methods. Third, long-term circulation of design through the recycling of resources by second-hand trade, the utilization of stock clothing, resale, and availability of eco-friendly materials through the development of new technologies. As an active practice for the sustainable fashion industry expands, it is expected that continuous research will be conducted as a future core value to realize the possibility of long-term circular zero-waste design through social responsibility and conscious recycling, reuse, and reproduction.

• Hip & pelvis
• /
• v.36 no.1
• /
• pp.26-36
• /
• 2024

Total hip arthroplasty (THA) is a frequently performed procedure; the objective is restoration of native hip biomechanics and achieving functional range of motion (ROM) through precise positioning of the prosthetic components. Advanced three-dimensional (3D) imaging and computed tomography (CT)-based navigation are valuable tools in both the preoperative planning and intraoperative execution. The aim of this study is to provide a thorough overview on the applications of CT scans in both the preoperative and intraoperative settings of primary THA. Preoperative planning using CT-based 3D imaging enables greater accuracy in prediction of implant sizes, leading to enhancement of surgical workflow with optimization of implant inventory. Surgeons can perform a more thorough assessment of posterior and anterior acetabular wall coverage, acetabular osteophytes, anatomical landmarks, and thus achieve more functional implant positioning. Intraoperative CT-based navigation can facilitate precise execution of the preoperative plan, to attain optimal positioning of the prosthetic components to avoid impingement. Medial reaming can be minimized preserving native bone stock, which can enable restoration of femoral, acetabular, and combined offsets. In addition, it is associated with greater accuracy in leg length adjustment, a critical factor in patients' postoperative satisfaction. Despite the higher costs and radiation exposure, which currently limits its widespread adoption, it offers many benefits, and the increasing interest in robotic surgery has facilitated its integration into routine practice. Conducting additional research on ultra-low-dose CT scans and examining the potential for translation of 3D imaging into improved clinical outcomes will be necessary to warrant its expanded application.

• Journal of Intelligence and Information Systems
• /
• v.22 no.4
• /
• pp.177-192
• /
• 2016

Machine learning is a field of artificial intelligence. It refers to an area of computer science related to providing machines the ability to perform their own data analysis, decision making and forecasting. For example, one of the representative machine learning models is artificial neural network, which is a statistical learning algorithm inspired by the neural network structure of biology. In addition, there are other machine learning models such as decision tree model, naive bayes model and SVM(support vector machine) model. Among the machine learning models, we use SVM model in this study because it is mainly used for classification and regression analysis that fits well to our study. The core principle of SVM is to find a reasonable hyperplane that distinguishes different group in the data space. Given information about the data in any two groups, the SVM model judges to which group the new data belongs based on the hyperplane obtained from the given data set. Thus, the more the amount of meaningful data, the better the machine learning ability. In recent years, many financial experts have focused on machine learning, seeing the possibility of combining with machine learning and the financial field where vast amounts of financial data exist. Machine learning techniques have been proved to be powerful in describing the non-stationary and chaotic stock price dynamics. A lot of researches have been successfully conducted on forecasting of stock prices using machine learning algorithms. Recently, financial companies have begun to provide Robo-Advisor service, a compound word of Robot and Advisor, which can perform various financial tasks through advanced algorithms using rapidly changing huge amount of data. Robo-Adviser's main task is to advise the investors about the investor's personal investment propensity and to provide the service to manage the portfolio automatically. In this study, we propose a method of forecasting the Korean volatility index, VKOSPI, using the SVM model, which is one of the machine learning methods, and applying it to real option trading to increase the trading performance. VKOSPI is a measure of the future volatility of the KOSPI 200 index based on KOSPI 200 index option prices. VKOSPI is similar to the VIX index, which is based on S&P 500 option price in the United States. The Korea Exchange(KRX) calculates and announce the real-time VKOSPI index. VKOSPI is the same as the usual volatility and affects the option prices. The direction of VKOSPI and option prices show positive relation regardless of the option type (call and put options with various striking prices). If the volatility increases, all of the call and put option premium increases because the probability of the option's exercise possibility increases. The investor can know the rising value of the option price with respect to the volatility rising value in real time through Vega, a Black-Scholes's measurement index of an option's sensitivity to changes in the volatility. Therefore, accurate forecasting of VKOSPI movements is one of the important factors that can generate profit in option trading. In this study, we verified through real option data that the accurate forecast of VKOSPI is able to make a big profit in real option trading. To the best of our knowledge, there have been no studies on the idea of predicting the direction of VKOSPI based on machine learning and introducing the idea of applying it to actual option trading. In this study predicted daily VKOSPI changes through SVM model and then made intraday option strangle position, which gives profit as option prices reduce, only when VKOSPI is expected to decline during daytime. We analyzed the results and tested whether it is applicable to real option trading based on SVM's prediction. The results showed the prediction accuracy of VKOSPI was 57.83% on average, and the number of position entry times was 43.2 times, which is less than half of the benchmark (100 times). A small number of trading is an indicator of trading efficiency. In addition, the experiment proved that the trading performance was significantly higher than the benchmark.

• The Korean Journal of Financial Management
• /
• v.27 no.1
• /
• pp.181-208
• /
• 2010

In July 2007, Korean government has passed "The Capital Market and Financial Investment Services Act" to further develop the capital markets and the Act was to become effective in February 2009. Using a large sample of Korean firms, we have examined (i) the effect of underwriting activities on the firm value (bond spread) comparing commercial bank and investment bank, and (ii) the determinants of the firm value changes following underwriting activities of bank. To test our goal, we collected a wide range of samples of data for bond issuing activities executed by Korean firms listed on the Korea Stock Exchange (KSE) between 2000 and 2003. Our paper is distinguished from previous studies on this subject in a way that we analyzed the effect of corporate bond underwriting activities with regard to commercial banking and investment banking. Initially, we set up a hypothesis that "Certification View" and "Conflict-of-interest View" are major driving forces behind cross-firm differences in performance following bond issuance. We find that, in general, underwriting by investment bank (securities company) brings a positive effect on the firm value (spread between bench mark rate and bond issuing rate). This result indicates that firm value has been negatively affected by the bank underwriting and provides the evidence for "Conflict-of-interest View" in Korea. Our studies have also revealed that any change in firm value following bond issuance is positively related with the firm size (total asset), operating performance, liquidity (cashflow), and equity ownership by foreign investors. Overall, our results support the view that bank underwriting activities can play an important role in determining firm value and financial strategies under "The Capital Market and Financial Investment Services Act" of 2007.

• Management & Information Systems Review
• /
• v.31 no.1
• /
• pp.221-246
• /
• 2012

The study examines the effects that non-audit service and firm's ownership structure might have on the value relevance directly or indirectly. This investigation is based on prior research which suggests that the audit firms' non-audit services is likely to adversely affect investors' perceptions of the credibility of financial reporting and that corporate governance are likely to mitigate the adverse this kind of non-audit services effects. The sample consists of non-banking firms listed on the Korea Exchange that reported annual financial statements over the period from 2004 to 2008. In the setting, stock returns as proxy for capital market response, auditor quality(measured as the discretionary accruals) is endogenously determined. This study employs a structural equation model to take into account the endogenous variables under study. The analysis influences through the path analysis that ownership structure suppress the market response through audit quality and also the non-audit service have influence on the market response through audit quality. The results of this study contribute to the literature in the following ways. First, this provides direct evidence that there is a negative association between audit firms' client importance and the value relevance. Second, the findings that the negative association is attenuated for audit quality support the findings of prior studies which present that corporate governance provide higher credibility of financial reports.

• Management & Information Systems Review
• /
• v.29 no.4
• /
• pp.333-357
• /
• 2010

Purposes of this paper are to investigate whether managers' compensation is sticky as accounting performance(ROA) vary or not and explore further what factors influence the managers' compensation stickiness. To empirically study the stickiness of managers' compensation, we used the financial data from manufacturing firms lised in the Korea Stock Exchange(1,000 firm-year data for 4 years). The results are as follows : First, managers' compensation is sticky with respect to change in accounting performance. That is, the increase in managers' compensation as accounting performance increases is greater than the decrease in managers' compensation in respect to equivalent decrease in accounting performance. Second, the degree of managers' compensation stickiness increases when managers have influence and contribution to firm value. Specifically, the degree of stickiness is positively associated with investment opportunity set, intangible assets' value, uncertainty of firms' operating environment, complexity of organizational hierarchy. But firms' size reversely impacts on the degree of managers' compensation stickiness.

• Journal of Korea Technology Innovation Society
• /
• v.15 no.3
• /
• pp.649-674
• /
• 2012

The purpose of this study is to investigate the effects of public R&D subsidies on private R&D. We have analyzed rationales for the public R&D subsidy from different perspectives. On the basis of literature review, a two step research model is constructed: participation phase (when firms benefit from public subsidies) and decision phase (when firms make decision on additional R&D investments). Using propensity score matching(PSM) method, we compare the potential outcome of the treated group to a matched controlled group of non-subsidized firms. The data used in this paper was collected from various sources. The Korean Innovation Survey 2008(manufacturing sector) is a main source of data. Financial data such as revenue, asset and capital stock, and number of employees were supplemented from the Nice Information Service KIS Value database. The R&D survey, conducted by MEST(Ministry of Education, Science and Technology) each year, was also used for the R&D expenditures of the manufacturing firms. This study comes up with the following empirical results. First, a firm's innovation capability, financial constraints, and sector appear to influence the selection of firms who were benefited from government's financial supports for R&D. Second, empirical results show that public R&D funding complements private investment on average and appear to have perpetual effects on the following year. Finally, sectoral difference in the effect of public subsidies on firms' R&D investment was confirmed. In addition, SMEs show more positive effects than large firms.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.29 no.4
• /
• pp.474-480
• /
• 1996

Physicochemical changes of milt during the spermiation period were investigated in black seabream (Acanthopagrus schlegeli) reared in recirculating seawater system. The spermiation period for the milt collection in cultured brood stock was from 11 April to 4 June. During the spermiation period, average milt volume (ml/100 g body weight) was $0.70{\pm}0.33\;ml$ and maintained high level from 2 May to 4 June. The total number of stripping spermatozoa per 100 g body weight reached the maximum value $(3.32{\times}10^{10})$ in 9 May, then decreased rapidly thereafter. Spermatozoa concentration per ml reached the minimum value in 2 May. There was no change in spermatocrit for the spermiation period. Total protein, total lipid, glucose and Na concentration in spermatozoa and seminal fluid were lower than those in plasma. Total protein, total lipid and K concentration in spermatozoa were higher than those in seminal fluid. The glucose concentration in spermatozoa and seminal fluid in April and May were significantly higher than those in June.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.41 no.2
• /
• pp.141-152
• /
• 2018

Although the 1997 Raw Data of the National Wealth Statistical Survey (South Korea) is timely 20-year-old data, it is meaningful as a benchmarking in the capital stock estimations of Korea, which is estimated by PIM (permanent inventory method). In the case of machinery/equipment, it is the data that can analyze in depth the changes in the industrial structure of Korea. In the case of ASL (average service life) which has economic concept, since the change of ASL is not so large, ASL yielded by the Raw Data of the 1997 National Wealth Statistical Survey is meaningful as reference value for the ASL estimated by the Bank of Korea and the National Statistical Office. As you know Japan has changed its service life due to changes in its industrial structure. However, many of its assets are still used for the years indicated in Showa (before 1989). The same trend with other countries such as Japan. However, the United States is constantly devoted to assessing the useful ASL and value of assets by distinguishing between the Hulten-Wykoff models and those not. Korea has also benchmarked the useful ASL of the United States and Japan when it conducted its own survey every 10 years by due diligence until 1997. In this study, the 'constraint' Iowa curve estimation by the Raw Data of the 1997 National Wealth Statistical Survey is based on the age records of the assets and the maximum age of the assets appropriately derived. And then we made modified Iowa curve by smoothing. From this modified one, we suggested ASL by asset. After 1997, the vintage disposal data directly were collected by the National Statistical Office with Oh Hyun Seung, Cho Jin Hyung, in order to estimate the useful ASL. Since then, the B/S team of the Economic and Statistics Bureau of the Bank of Korea has been working on a new concept of content training.