• Journal of Intelligence and Information Systems
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• v.27 no.1
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• pp.65-82
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• 2021

Stock market investors are generally split into foreign investors, institutional investors, and individual investors. Compared to individual investor groups, professional investor groups such as foreign investors have an advantage in information and financial power and, as a result, foreign investors are known to show good investment performance among market participants. The purpose of this study is to propose an investment strategy that combines investor-specific transaction information and machine learning, and to analyze the portfolio investment performance of the proposed model using actual stock price and investor-specific transaction data. The Korea Exchange offers daily information on the volume of purchase and sale of each investor to securities firms. We developed a data collection program in C# programming language using an API provided by Daishin Securities Cybosplus, and collected 151 out of 200 KOSPI stocks with daily opening price, closing price and investor-specific net purchase data from January 2, 2007 to July 31, 2017. The self-organizing map model is an artificial neural network that performs clustering by unsupervised learning and has been introduced by Teuvo Kohonen since 1984. We implement competition among intra-surface artificial neurons, and all connections are non-recursive artificial neural networks that go from bottom to top. It can also be expanded to multiple layers, although many fault layers are commonly used. Linear functions are used by active functions of artificial nerve cells, and learning rules use Instar rules as well as general competitive learning. The core of the backpropagation model is the model that performs classification by supervised learning as an artificial neural network. We grouped and transformed investor-specific transaction volume data to learn backpropagation models through the self-organizing map model of artificial neural networks. As a result of the estimation of verification data through training, the portfolios were rebalanced monthly. For performance analysis, a passive portfolio was designated and the KOSPI 200 and KOSPI index returns for proxies on market returns were also obtained. Performance analysis was conducted using the equally-weighted portfolio return, compound interest rate, annual return, Maximum Draw Down, standard deviation, and Sharpe Ratio. Buy and hold returns of the top 10 market capitalization stocks are designated as a benchmark. Buy and hold strategy is the best strategy under the efficient market hypothesis. The prediction rate of learning data using backpropagation model was significantly high at 96.61%, while the prediction rate of verification data was also relatively high in the results of the 57.1% verification data. The performance evaluation of self-organizing map grouping can be determined as a result of a backpropagation model. This is because if the grouping results of the self-organizing map model had been poor, the learning results of the backpropagation model would have been poor. In this way, the performance assessment of machine learning is judged to be better learned than previous studies. Our portfolio doubled the return on the benchmark and performed better than the market returns on the KOSPI and KOSPI 200 indexes. In contrast to the benchmark, the MDD and standard deviation for portfolio risk indicators also showed better results. The Sharpe Ratio performed higher than benchmarks and stock market indexes. Through this, we presented the direction of portfolio composition program using machine learning and investor-specific transaction information and showed that it can be used to develop programs for real stock investment. The return is the result of monthly portfolio composition and asset rebalancing to the same proportion. Better outcomes are predicted when forming a monthly portfolio if the system is enforced by rebalancing the suggested stocks continuously without selling and re-buying it. Therefore, real transactions appear to be relevant.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.2
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• pp.65-80
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• 2022

Despite the uncertainty and risky factors of startups, the special and critical role of accelerators in carrying out professional nurturing and investment for them is becoming increasingly significant in the startup social-system. However, academic research on investment determinants that have a profound impact on the survival of accelerators is lacking, and there are only a few empirical studies on the classification and importance of factors, and they do not enjoy the benefits of theoretical studies. This study proposes a business model innovation framework based on the business model innovation theory that reflects the nature and properties of startups that are investment targets of accelerators and derives 12 investment decision factors. The framework defines that the target, direction, and performable force of startup innovation are a business model, strategy, and dynamic capability. Besides, the framework analyzes the investment decision factors of the existing accelerators based on the business model innovation framework to verify the suitability and sufficiency of the composition. As a result of the analysis, first, most of the items were faithfully composed from a static point of view of business model innovation, but it was found that the factors related to the core activities to evaluate the activity and customer relationship were insufficient. Second, from the strategic point of view, the necessity of developing factors that can encompass the definition and content of core resources, which are internal strategic factors, was raised. Third, from the dynamic point of view, it was found that many of the investment determinants of accelerators were concentrated on the lower level of dynamic competencies. This can be judged as a result of reflecting the characteristics of a startup that needs to develop a solution with few resources and a small number of team members. In addition, the roles and interrelationships between each factor are not clear, thus it was found as a limiting point for startups to view and evaluate the direction and process in which startups dynamically innovate their business models. This study is considerably differentiated in that it provides a business model innovation framework and offers a theoretical basis for investment determinants by deriving the investment determinants of accelerators based on the framework and design the foundation for subsequent research. The business model innovation framework presented in this study has great implications in that it contributes to the achievement of startups, accelerators, and startup support organizations.

• Journal of Physiology & Pathology in Korean Medicine
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• v.32 no.4
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• pp.232-246
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• 2018

The purpose of this research is to contribute to clinical researches on neck pain and cervical spondylosis by reviewing the latest research trends and evaluation tools through the analyses of clinical studies on neck pain and cervical spondylosis over the last 5 years. 70 papers satisfying the selection conditions among the RCT papers that had been searched as "neck pain" or "cervical spondylosis" at Pubmed(https://www.ncbi.nlm.nih.gov/pubmed) from March 2011 to February 2016 were targeted. Papers were numbered in order of their publication dates and analyzed by classifying their contents into 1) pain classification, 2) treatment type, 3) treatment duration, 4) treatment time, 5) number of participants, 6) evaluation tools and methods of research, and 7) evaluation duration. 55 papers targeted chronic neck pain, 6 papers acute and subacute neck pain, and 2 papers subacute and chronic neck pain. In comparison by intervention, 43 papers corresponded to physical therapy, 3 papers to acupuncture, 1 to herbal fomentation, 5 to medication, and 18 papers corresponded to multilateral comparisons comparing the efficacy by various interventions. In research period, there were 50 papers based on treatment period, 16 papers based on the number of treatments, and 4 papers based on different periods depending on each group. In treatment duration, the cases from 1 month or more to less than 3 months were most, followed by the cases of less than 1 month, and the cases from 3 months or more to less than 6 months. In treatment frequency, the number of treatments of the treatment group was the same as that of the control group in 51 papers, and many treatments were conducted by the methods of acupuncture, manual therapy, and injection therapy in cases of once or twice of treatments, and physical therapy and electroacupuncture corresponded mainly to the cases from 3 times or more to less than 10 times of treatments, and retrospective observation and exercise programs corresponded mainly to the cases of more than 30 times of treatments. In the number of subjects of the researches, the cases from 50 or more to less than 100 were most, followed by the cases from 20 or more to less than 50. There were 7 evaluation tools cited 10 times or more: VAS, NRS, PPT, NDI, NPQ, CROM, and SF-36. In evaluation period, 37 papers evaluated only during the treatment period, and 33 papers conducted follow-up. In follow-up period, the cases of less than 3 months were most, followed by the cases from 6 months or more to less than 1 year, and the cases from 3 months or more to less than 6 months. When planning clinical researches on cervical pain in the future, appropriate intervention methods, frequency and duration of treatment, period of follow-up, appropriate number of subjects and selection of evaluation tools for objective validity will have to be considered. In addition, randomization, double-blind, etc. will have to be considered for researches with high basis level.

• Journal of the Korean earth science society
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• v.40 no.6
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• pp.572-583
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• 2019

In this study, the atmospheric vertical structure (AVS) associated with summertime (June, July, and August) heavy rainfall in Seoul was classified into three patterns (Loaded Gun: L, Inverted V: IV, and Thin Tube: TT) using rawinsonde soundings launched at Osan from 2009 to 2018. The characteristics of classified AVS and precipitation property were analyzed. Occurrence frequencies in each type were 34.7% (TT-type), 20.4% (IV-type), 20.4% (LG-type), and 24.5% (Other-type), respectively. The mean value of Convective Available Potential Energy (1131.1 J kg^-1) for LG-types and Storm Relative Helicity (357.6 ㎡s^-2) for TT-types was about 2 times higher than that of other types, which seems to be the difference in the mechanism of convection at the low level atmosphere. The composited synoptic fields in all cases showed a pattern that warm and humid southwesterly wind flows into the Korean Peninsula. In the cases of TT-type, the low pressure center (at 850 hPa) was followed by the trough in upper-level (at 500 hPa) as the typical pattern of a low pressure deepening. The TT-type was strongly influenced by the low level jet (at 850 hPa), showing a pattern of connecting the upper- and low-level jets. The result of analysis indicated that precipitation was intensified in the first half of all types. IV-type precipitation induced by thermal instability tended to last for a short term period with strong precipitation intensity, while TT-type by mechanical instability showed weak precipitation over a long term period.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.1
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• pp.14-24
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• 2016

Information on the lists of pollutants from industrial wastewater discharge are essential not only to specify the key pollutants to be managed in permission process but to design the treatment facilities by the dischargers. In this study, wastewater quality analysis was conducted for three industrial categories including the specified hazardous water pollutants. The general description of the wastewater occurrence, major sources, treatment facilities are also investigated to obtain integrated database on the pollutant inventories for the industrial categories. In addition Based on the analysis of raw wastewater and final effluent, the detected pollutant items are confirmed by analyzing their presence in the raw or supplement materials, the potential of formation as byproducts, and the possibility of inclusion as impurities. The three industrial categories include petrochemical basic compounds, basic organic compounds, and thermal power generation. The water pollutants emitted from petrochemical basic compound manufacturing facilities are 31 items including 16 specified hazardous water pollutants. Basic organic compound manufacturing facilities discharge 30 kinds of pollutants including 14 specified hazardous water pollutants. Thermal power generation facilities emit 20 pollutants, 8 specified hazardous water pollutants among them. These substances were decided as emission inventories of water pollutants finally through the probability evaluation. The compounds detected for each categories are screened through investigation on the possible causes of their occurrence and confirmed as the final water pollutant inventories.

• Journal of Gastric Cancer
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• v.5 no.2
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• pp.101-105
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• 2005

Purpose: Some gastric cancer patients in whom the cancer has infiltrated up to the muscularis propria (mp) have a good postoperative course similar to that of early gastric cancer (EGC) patients (this does not match the general classification of gastric cancer). Therefore, we performed a retrospective analysis of 125 patients with mp gastric cancer based on the degree of mp invasion. Materials and Methods: The clinicopathologic features of 125 cases of mp gastric cancer were subdivided according to depth of invasion, and were retrospectively reviewed and compared with the surgical features of 222 patients with gastric cancer invading the submucosa (sm). For each tumor, using the section that showed the greatest extent of invasion, we evaluated the degree of tumor invasion into the mp layer at a magnification of $\times$100. The patients were classified into 2 groups: mp1, the tumor was limited to the first of the 3 mp layers, and mp2, the tumor had expanded beyond the first layer. Results: Patients with mp1 (n=50) had a significantly lower incidence of lymph node metastasis, and a smaller tumor size than patients with mp2 (n=75) (P=0.01 and P=0.029, respectively). The 5-year survival rate of mp1 patients was significantly better than that of mp2 patients ($95.3\%\;vs.\;77.6\%$, P=0.0282), but was similar to that ($91.2\%$) of the 222 sm patients. The 5-year survival rate of mp patients without lymph node metastasis (n=55) was significantly better than that of those with lymph node metastasis (n=70)($93.3\%\;vs.\;78.2\%$, P=0.0192). Patients with mp1 had a significantly higher incidence of lymph node metastasis ($42.5\%\;vs\;23\%$, P=0.006) than patients with sm. Conclusion: There were clear differences in clinical features between the mp1 and the mp2 patients. Subdivision of mp gastric cancer according to the depth of invasion may enable a more precise prognosis and a more pertinent treatment plan for mp patients. In particular, as the clinicopathological findings and surgical outcomes for mp1 patients were akin to those of the sm patients, mp1 patients may require treatment analogous to that administered to patients with sm gastric cancer. (J Korean Gastric Cancer Assoc 2005;5:101-105)

• Journal of the Korean Chemical Society
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• v.58 no.6
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• pp.600-611
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• 2014

In this study, we sampled science writing tasks and investigated their frequency of use shown in the chemistry domain from two sets of 18 middle school science textbooks developed under the 2007 Revised National Curriculum(RNC) and the 2009 RNC, respectively. In addition, we categorized the sampled science writing tasks depending on the cognitive process and type of writing and compared with the results obtained from analysis of global issues presented in the science writings. From the textbooks developed under the 2007 RNC, a total of 183 science writing tasks were identified in which 10.17 tasks per textbook and 1.32 tasks per 10 pages were used averagely. A total of 168 were identified from the textbooks for the 2009 RNC. Among them, 9.33 tasks per textbook and 1.23 tasks per 10 pages were used on average. Comparing with these results, the average frequency of use of the tasks per textbook and per ten pages were decreased, respectively. Moreover, the number of science writing tasks were found in each curriculum varied considerably depending on the units and the publishers, and that the writing tasks were mainly arranged in the finale, wrapping up stage. In the analysis of science writing tasks according to the cognitive process, the highest and lowest frequency of use were observed in the category of 'understand' and 'remember', respectively. According to the classification of science writing tasks based on the types of writing, the writings for the information delivery were most used and the highest frequency of use was observed in the category of 'understand' of the cognitive process belonging to 'information delivery'. As for the results of the analysis of global issues, the number of science writing tasks including global issues increased from 21(11.48%) in the 2007 RNC to 33(19.64%) in the 2009 RNC. Furthermore, science writing tasks associated with protection of environment showed the highest frequency of use in the both curriculums, and it was analyzed that the materials of global issues used in the 2009 RNC were much more diverse.

• Asia pacific journal of information systems
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• v.19 no.2
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• pp.179-193
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• 2009

As the common saying attests, a publish-or-perish world, publishing is absolutely critical for academic researchers' successful careers. It is the most objectively-accepted academic performance criteria and the most viable way to attain public and academic recognition. Asia Pacific Journal of Information Systems(APJIS) has been recognized as the most influential domestic journal in Korean MIS field since July, 1991. Therefore, publishing in APJIS means your research is original, valid, and contributive. While most researchers learn how to publish an article in APJIS through a repetitive review process, thereby improving their chance of the' accepted' through their personal trial and error experiences, such valuable lessons and know-how tend to be kept personally and rarely shared. However, useful insights into research and publication skills could be also gained from sharing others' errors, neglect, and misjudgments which are equally critical in improving researchers' knowledge in the field (Murthy and Wiggins, 2002). For this reason, other academic disciplines make systematic efforts to examine the paper review process of major journals and share the findings from these studies with the rest of the research community members (Beyer et al., 1995; Cummings et al, 1985; Daft, 1995; Jauch and Wall, 1989; Murthy and Wiggins, 2002). Recognizing the urgent need to provide such type of information to MIS research community in Korea, we have chosen the most influential academic journal, APJIS with an intention to share the answer to the following research question: "What are the common problems found in the manuscripts either 'rejected' or 'required a major revision' by APJIS reviewers?" This study analyzes the review results of manuscripts submitted to APJIS (from January, 2006 to October, 2008), particularly those that were 'rejected' or required a 'major revision' at the first round. Based on Daft's(1995) study, twelve most-likelihood problems were defined and used to analyze the reviews. The twelve criteria for classification, or "twelve problems", are as follows: No theory, Concepts and operationalization not in alignment, Insufficient definition--theory, Insufficient rationale--design, Macrostructure--organization and flow, Amateur style and tone, Inadequate research design, Not relevant to the field, Overengineering, Conclusions not in alignment, Cutting up the data, and Poor editorial practice. Upon the approval of the editorial board of APJIS, the total 252 reviews, including 11 cases of 2005 and 241 cases from July, 2006 to October, 2008, were received without any information about manuscripts, authors, or reviewers. Eleven cases of 2005 were used in the pilot test because the data of 2005 were not in complete enumeration, and the 241 reviews (113 cases of 'rejection' and 128 ones of 'major revision') of 2006, 2007, and 2008 were examined in this study. Our findings show that insufficient rationale-design(20.25%), no theory(18.45%), and insufficient definition--theory(15.69%) were the three leading reasons of 'rejection' and 'major revision.' Between these two results, the former followed the same order of three major reasons as an overall analysis (insufficient rationale-design, no theory, and insufficient definition-theory), but the latter followed the order of insufficient rationale--design, insufficient definition--theory, and no theory. Using Daft's three major skills-- 'theory skills', 'design skills', and 'communication skills'-- twelve criteria were reclassified into 'theory problems', 'design problems', and 'communication problems' to derive more practical implications of our findings. Our findings show that 'theory problems' occupied 43.48%, 'design problems' were 30.86%, and 'communication problems' were 25.86%. In general, the APJIS reviewers weigh each of these three problem areas almost equally. Comparing to other disciplines like management field shown in Daft's study, the portion of 'design problems' and 'communication problems' are much higher in manuscripts submitted to the APJIS than in those of Administrative Science Quarterly and Academy of Management Journal even though 'theory problems' are the most predominant in both disciplines.

• Journal of the Korean Arthroscopy Society
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• v.16 no.2
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• pp.128-133
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• 2012

Purpose: This study examined the relationship between graft appearance on follow-up magnetic resonance imaging (MRI) and knee stability after double bundle anterior cruciate ligament (ACL) reconstruction. Materials and Methods: For each patient, 1.5 tesla MRI's were obtained. The signal intensity of grafts was divided into 3 grades by Sononda's classification. The course of grafts was divided into two patterns: straight and curved. We assessed Lachman test, KT 2000 arthrometer and anterior drawer stress radiograph using Telos$^{(R)}$ in $30^{\circ}$ knee flexion for anterior stability and evaluated pivot shift test for rotatory stability. The correlation between graft appearance on MRI and the results of knee stability tests was evaluated. Results: The anteromedial (AM) graft was evaluated as being grade 1 in 66.7%, grade 2 in 26.7%, and grade 3 in 6.7% of the cases and the posterolateal (PL) graft was assessed as being grade 1 in 63.3%, grade 2 in 33.3%, and grade 3 in 3.3% of the cases according to the signal intensity. The AM graft was evaluated as being straight in 83.3% and curved in 16.7% of the cases, and the PL graft was assessed as being straight in 86.7% and curved in 13.3% of the cases according to the course. The course of AM graft was correlated with the results of anterior stability tests and the course of PL graft was correlated with the result of rotatory stability test. However, the signal intensity of grafts was not correlated with the results of anterior stability and rotatory stability tests. Conclusion: The course of AM is correlated with anterior stability and the course of PL is correlated with rotatory stability on follow-up MRI after double bundle ACL reconstruction.

• Journal of Embryo Transfer
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• v.21 no.1
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• pp.21-27
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• 2006

This study was conducted to determine the distribution of cat follicles among varying ages and produce oocytes from preantral follicles cultured in vitro. We used ovaries from 41 cats ranging in age from 0.3 to 5 years. Ovaries were obtained from cats undergoing routine ovariectomy at local veterinary clinics. As a prelude to in vitro culture of preantral follicles, the length and the width and the weight of ovaries among cats of varying ages were measured. Ovaries were fixed in 10% formalin, embedded in paraffin, cut into $3{\mu}m$-sections, mounted on slides and stained with hematoxylin and eosin. Follicles were evaluated at 200X and 400X magnification. Distribution of follicles among cats of varying ages were evaluated according to follicle classification: primordial, primary, transitional, preantral and antral follicles. Preantral follicles were isolated by the simple mechanical procedure. Each follicle was cultured in a well containing $100{\mu}l$ of medium 199 supplemented with 10% fetal bovine serum (FBS) or polyvinylalcohol (PVA) for 16 days. Follicle diameters were measured under inverted microscope every 4 days. The length, the width and the weight of ovaries were increased gradually according to ages but there was not significant difference among cats of varying ages. Majority of follicles were primordial follicles (84%) regardless of cat ages (p<0.05). Follicle diameter increased until 4 days of culture. However, period longer than 4 days of culture in vitro had a deleterious effect on follicle survival regardless of supplement (FBS or PVA). A few oocytes were collected from preantral follicles cultured in vitro. These basic reproductive techniques in domestic cats can be a useful tool to save endangered feline species.