• The Journal of Information Technology
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• v.7 no.3
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• pp.19-36
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• 2004

This study examines the relation between accruals components of earnings and stock return. Earnings are decomposed into four components: discretionary accruals, nondiscretionary accruals, nondiscretionary income and cash flow from operations. Because reported earnings in financial statement consist of cash flow from operations plus total accruals. We decompose total accruals into a discretionary accruals and a nondiscretionary accruals separately. This paper examines the incremental informational content of discretionary accruals and nondiscretionary accruals components of net income by regressing return on earnings' components in multivariate models. The empirical analysis is conducted on a sample of 1,580 firm-years comprising 158 firms during 1991-2003. discretionary accruals are obtained by decomposing total accruals into discretionary and nondiscretionary accruals conponents, using a pooled variation of the Jones model(1991). These findings suggest that the discretionary accruals(measured using a variation the Jones model) is priced by the stock market. Specifically, the discretionary accruals and cash flow from operations are positively associated with the stock return, and also nondiscretionary income, discretionary accruals are positively associated with the stock return. While this result is consistent with the market prices the discretionary accruals because it captures value-relevant information. Additional test report evidence consistent with nondiscretionary accruals conveying information about the stock return.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.6
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• pp.121-132
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• 2018

Weather is an important factor affecting roadway transportation in many aspects such as traffic flow, driver 's driving patterns, and crashes. This study focuses on the relationship between weather and road surface condition and develops a model to estimate the road surface condition using machine learning. A road surface sensor was attached to the probe vehicle to collect road surface condition classified into three categories as 'dry', 'moist' and 'wet'. Road geometry information (curvature, gradient), traffic information (link speed), weather information (rainfall, humidity, temperature, wind speed) are utilized as variables to estimate the road surface condition. A variety of machine learning algorithms examined for predicting the road surface condition, and a two - stage classification model based on 'Random forest' which has the highest accuracy was constructed. 14 days of data were used to train the model and 2 days of data were used to test the accuracy of the model. As a result, a road surface state prediction model with 81.74% accuracy was constructed. The result of this study shows the possibility of estimating the road surface condition using the existing weather and traffic information without installing new equipment or sensors.

• Management & Information Systems Review
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• v.30 no.4
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• pp.147-173
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• 2011

It is generally accepted that there are momentum effects in the short term and reversal effects in the long term, which makes abnormal excess returns in the major stock markets in the world. In Korea stock market, however, the previous studies demonstrate that contrarian strategies based on reversal effects are more effective than momentum strategies following momentum effects in the short term as well as in the long term. This paper examines wether contrarian strategies are still effective In Korea stock market from 1980 to 2009, and the short term reversals may be changed after the foreign exchange crisis in 1997-1998. Moreover, this paper investigates how contrarian profits are shown considering the state of market. In my research, unlike previous studies, I find that both of contrarian strategies using price change and price level cannot gain excess risk adjusted returns in Korea stock market from 1980 to 2009, but this result is due to the fact that reversal effects existed before the foreign exchange crisis but momentum effects does after the foreign exchange crisis in 1997-1998. Specially, after the foreign exchange crisis, it is confirmed momentum strategies using 52 week high price, that is, price level are more effective than momentum strategies using price change. And following the strategies using 52 week high price after the foreign exchange crisis, the momentum is not only observed in the up market but also in the down market, which is different with the results of the studies regarding to American market, where the momentum is just found in the up market.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.35-48
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• 2022

Fish assemblage of total 325 of Korean peninsula estuaries were surveyed to analyze the characteristics of community structure and diversity by sea areas for three years from 2016 to 2018. The scale (stream width) of Korean estuaries were various (14~3,356 m), and 68.9% of all estuaries showed salinity of less than 2 psu. Total 149 species classified into 52 families of fish were identified, and the dominant and sub-dominant species were Tribolodon hakonensis (relative abundance, RA, 12.5%) and Mugil cephalus (RA, 9.5%), respectively. The estuary of the Korean Peninsula had different physical and chemical habitat environments depending on the sea area, and accordingly, fish community structure also showed statistically significant differences (PERMANOVA, Pseudo-F=26.69, P=0.001). In addition, the NMDS (nonmetric multidimensional scaling) results showed the patterns that indicating fish community difference by sea areas, even though low community similarity within sea area (SIMPER, 21.79~26.39%). The estuaries of east sea areas were distinguished from the others in the aspects of which, the higher importance of migratory fishes and endangered species, and that of brackish species were characterized at south sea estuaries. However, the estuaries of west sea showed higher importance of species that have a relation with freshwater (primary freshwater species, exotic species), which is the result that associating with the lower salinity of west sea estuaries because of the high ratio of closed estuaries(78.2%). The SIMPER analysis, scoring the contribution rates of species to community similarity, also showed results corresponding to the tendency of different fish community structures according to each sea area. So far, In Korea, most studies on fish communities in estuaries have been conducted in a single estuary unit, which made it difficult to understand the characteristics of estuaries at the national level, which are prerequisite for policy establishment. In present study, we are providing fish community structure characteristics of Korean estuaries in a national scale, including diversity index, habitat salinity ranges of major species, distribution of migratory species. We are expecting that our results could be utilized as baseline information for establishing management policies or further study of Korean estuaries.

• Korean Journal of Ecology and Environment
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• v.57 no.2
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• pp.102-110
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• 2024

This study presents a fine scale distribution of the endangered species, Odontobutis obscura, through field surveys and literature reviews. Using the mark-recapture method, the population size in major habitats was determined. Field surveys conducted on 18 streams in Geoje Island revealed that the O. obscura was only found in the main streams and tributaries of the Sanyang, Gucheon, and Buchun Streams, which are part of the Sanyang Stream watershed. The O. obscura exhibited relative abundances ranging from 0.5% to 35.3% at different locations, with certain spots showing higher relative abundances (18.8% to 35.3%), indicating major habitat areas. A review of six literature studies confirmed the presence of the O. obscura, although there were differences in occurrence status depending on the purpose, scope, and duration of the studies. Combining the results of field and literature surveys, it was found that the O. obscura inhabits the main and tributary streams of the Sanyang, Gucheon, and Buchun Streams, from the upper to lower reaches. Currently, the O. obscura population in the Sanyang Stream watershed maintains a stable habitat, but its limited distribution range suggests potential issues such as genetic diversity deficiency in the long term. The population size of the O. obscura was confirmed at two specific locations, with densities of 0.5 to 1.5 individuals per m². The average movement distance from the release point was 13.1 m, indicating the limited mobility characteristic of ambush predators. Understanding the distribution and population size of endangered species is the first step towards their conservation and protection. Based on this information, further research could significantly contribute to the conservation of the O. obscura.

• Journal of KIISE:Databases
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• v.37 no.4
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• pp.177-184
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• 2010

In these day, many data including sensor, delivery, credit and stock data are generated continuously in massive quantity. It is difficult to learn from these data because they are large in volume and changing fast in their concepts. To handle these problems, learning methods based in sliding window methods over time have been used. But these approaches have a problem of rebuilding models every time new data arrive, which requires a lot of time and cost. Therefore we need very simple incremental learning methods. Bayesian method is an example of these methods but it has a disadvantage which it requries the prior knowledge(probabiltiy) of data. In this study, we propose a learning method based on attribute values. In the proposed method, even though we don't know the prior knowledge(probability) of data, we can apply our new method to data. The main concept of this method is that each attribute value is regarded as an expert learner, summing up the expert learners lead to better results. Experimental results show our learning method learns from data very fast and performs well when compared to current learning methods(decision tree and bayesian).

• Information Systems Review
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• v.19 no.3
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• pp.201-228
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• 2017

Vulnerability information, which can cause serious damage to information assets, has become a valuable commodity, thereby leading to the creation of a vulnerability market. Vulnerability information is traded on the vulnerability market from several hundred dollars to hundreds of thousands of dollars depending on its severity and importance, and the types and scope of the vulnerability markets are varying. Based on previous studies on vulnerability markets and hackers, this study empirically analyzed the effects of the security researcher's vulnerability research motivation on his/her vulnerability market use intention. The results are discussed as follows. First, vulnerability research self-efficacy had a significant effect on flow and on white and black market use intention but not on perceived benefit. Second, flow had a significant effect on perceived benefit and on black market use intention but had no effect on white market use intention. Third, perceived profit had a significant effect on white and black market use intention. Fourth, vulnerability research self-efficacy had a significant effect on perceived benefit through flow. Fifth, flow had a significant effect on white and black market use intention through perceived profit. These findings can be used to predict the behavior of security researchers who have experience in exploiting vulnerabilities.

• The KIPS Transactions:PartD
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• v.8D no.2
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• pp.132-144
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• 2001

The broadcast environment is asymmetric communication aspect that is typically much greater communication capacity available from server to clients than in the opposite direction. In addition, most of mobile computing systems only allow the generation of read-only transactions from mobile clients for retrieving different types of information such as stock data, traffic information and news updates. Since previous concurrency control protocols, however, do not consider such a particular characteristics, the performance degradation occurs when those schemes are applied to the broadcast environment having quite a high data contention. In this paper, we propose OCC/2VTS (Optimistic Concurrency Control based on 2-Version and TimeStamp) that is most appropriate for broadcast environment. OCC/2VTS lets each client process and commit query transactions for itself by using two version data in cache. If the values of appropriate data items are not changed twice by invalidation report after a query transaction starts, the query transaction is committed safely independent of commitment of update transactions. OCC/2VTS decreases the number of informing server for the purpose of commitment. Due to broadcasting the validation reports including updated recent values, it reduces the opportunity of requesting a recent data values of server as well. As a result, OCC/2VTS makes full use of the asymmetric bandwidth. It also improves transaction throughput by increasing the query transaction commit ratio as much as possible.

• Management & Information Systems Review
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• v.38 no.4
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• pp.113-136
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• 2019

Business performance is the ultimate output of company's effort. So in all academic area of business, scholars have tried to identify influencing factors on the business performance. This study also try to identify the factors and relati on among factors focusing on market orientation and relationship specific investment. Based on the literature review, we developed hypotheses. To examine the hypotheses we gathered survey data from B2B companies located in the Ulsan and 288 survey data was used to the analysis. Research results are as follows. As sub-factor of market orientation intelligence generation and responsiveness to intelligence affected on the relationship specific investment significantly and relationship specific investment also affected performance significantly. But all sub-factors of market orientation didn't influenced performance significantly meaning the mediating effect of relationship specific investment between market orientation and performance. Finally, the relation between intelligence generation and relationship specific investment was moderated negatively by dependence. The theoretical and practical implications of this study and limitations were discussed.

• Information Systems Review
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• v.22 no.1
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• pp.33-57
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• 2020

Although cryptocurrency which can promote innovation in the blockchain ecosystem is published for many useful purposes, in Korea, cryptocurrency is recognized only as a means of investment for the profit. The fact emphasizes only the speculative nature of the cryptocurrency, so investor negates the fundamental purpose of cryptocurrency and hinders innovation in the blockchain ecosystem. The purpose of this study is to investigate the cause of cryptocurrency perception and speculative behavior of domestic cryptocurrency investors from an academic perspective. We use a model that reflects the traditional considerations and cryptocurrency's characteristics in investment. Using the model, we can explain the cause of misperception of cryptocurrency through the theory of bounded rationality. In building the research model, we use variables of venture and angel investor's consideration used in investment decisions and collect the keywords from indexes of whitepaper to reflect the properties of cryptocurrency. This study mentions that, due to the imitations presented by Simon, individuals are forced to perceive cryptocurrency as a means of speculation and to make irrational decisions that impair ecosystem health. We analyze whether there is a significant difference in rationality in decision made by the sample under limited knowledge and imperfect information constraints. As a result, imperfect information constraints led investors to consider only irrational criteria in decision making. From this result, this study suggests that information asymmetry needs to be relaxed so that investment can be pursued together with rational investment and development of blockchain ecosystem. In addition, the industry can capture strategic insights for successful financing through ICO by enabling better understanding of investor decision-making.