• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.12
• /
• pp.611-620
• /
• 2016

Firms grow in a competitive environment and competition can be a source of corporate growth. In an increasingly global market, companies face increased competition. As such, it is natural that all firms face some degree of risk due to competition. While firms compete for market share, they also imitate competitors in order to minimize risk that accompanies competition. This research attempts to demonstrate the effects of inter-firm competition on investment decisions. Using idiosyncratic equity returns as the instrument variable, this paper uses a two-stage least squares regression, as well as an ordinary least squares (OLS), to identify the influence of peer firms' investment decisions on a firm's own investment strategy. The results confirm that firms show stronger imitative behavior with more intense competition. Also, firms with higher debt ratios show higher peer group influence. This imitative factor provides clues to measure the risk-averseness in investment decisions.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.33 no.4
• /
• pp.346-351
• /
• 2011

Purpose: The purpose of this study was to measure the angular differences between the horizontal reference planes on the CBCT generated PA cephalogram and the modified interpupillary plane, which was usually used in the clinical examination, and to evaluate the validity of the horizontal reference planes. Methods: The CBCT generated PA cephalogram was used to measure the angles between the FH, Lo and IP planes. The subjects consisted of 42 patients with facial asymmetry (males: 21, females: 21, mean-age: 21.6 years). The control groups were also assessed (males: 10, females: 10, mean-age: 23.8 years). The distance of the interpupil was measured on the soft-tissue volume rendered image. The angular differences were statistically analyzed using the $Mann-Whitney$ $U$ $test$ for inter-group comparisons and the $Friedman$ $test$ for intra-group comparisions. Results: The angle between the FH plane and IP plane (the angle of the FH-IP line) showed a statistically significant difference between the two groups ($p$ <0.05). There was no statistical differences between each angle (angle of the FH-IP line, angle of the FH-Lo line, angle of the Lo-IP line) on the intra-group comparision ($p$ >0.05). Conclusion: The angle between the Lo line and IP line (angle of the Lo-IP line) showed no statistically significant difference in both the control and asymmetry groups. Therefore, the Lo line could be used as a horizontal reference plane in CBCT generated PA cephalograms.

• Korean Journal of Childcare and Education
• /
• v.9 no.1
• /
• pp.129-148
• /
• 2013

The purpose of this study is to examine the relationships between fathers and children with Internet addiction. To achieve the goal, researchers chose face to face interview methods with 12 children who had been considered'at risk'with Internet addiction. More specifically, examiners conducted individual in-depth interviews with 12 children associated with Internet addiction for 30~40 minutes during four sessions through structured questions and non-structured questions. After collecting data, examiners conducted a categorical analysis based on collected data. Finally, the research results, discovered in this research, were as follows: First, the Internet set up the inter-generational barrier in the relationship between father and child, second, children took an interest in the Internet instead of their busy father, Third, the Internet played the role of a place to escape from the awkwardness with their father, fifth, fathers were not able to control the Internet use of their children. Based on the research results, this study suggests a desirable behavior pattern for fathers which can be conducive to children with Internet addiction and their fathers along with a follow-up study.

• The korean journal of orthodontics
• /
• v.53 no.2
• /
• pp.116-124
• /
• 2023

Objective: The absence of a guideline to refer to developing malocclusions appropriately, may be a contributing factor to the inadequacy of timely interceptive orthodontics provision. This study aimed to develop and validate a new orthodontic grading and referral index to be used by dental frontliners to prioritize the orthodontic referral of developing malocclusion in children based on its severity. Methods: A cross-sectional study involving clinical assessment with 413 schoolchildren aged between 8.1 and 11.9 years was conducted in 2018. All the presenting malocclusion was listed and graded based on a few dental guidelines to produce the draft index. The validity and reliability of the draft index were tested using twenty study models. Face and content validation was carried out using the content validation index and Modified Kappa Statistics. Results: Fourteen dental and occlusal anomalies were identified as components of malocclusion and three grades of referral (monitor, standard, urgent) were included in the final index. The scale-level content validity index average value of 0.86 and 0.87 was obtained for content and face validation, respectively. There was moderate to excellent agreement in the Modified Kappa Statistics for both validations. Excellent inter- and intra-assessor agreement was obtained. The new index displayed valid and reliable scores. Conclusions: The Index for Interceptive Orthodontics Referral was developed and validated for the dental frontliners to identify and prioritize the developing malocclusion in children based on its severity and refer for orthodontic consultation to increase the possibility for interceptive orthodontics.

• Korean Journal of Culture and Social Issue
• /
• v.10 no.1
• /
• pp.1-30
• /
• 2004

Study 1 composed of three experiments examined differences in person perception between computer-mediated (or CMC) and face-to-face (or FTF) communications. In Experiment 1, each of 17 groups of 4-5 discussed a donation entrance system through CMC and a week later a college-based university system through FTF communication mode for half an hour. Then members of a given group rated each other along with self-ratings on five personality traits. Results indicated that in FTF than CMC condition, ratings of others were more positive and also self-peer agreement and meta-accuracy were larger in spite of no large difference in inter-judge agreement between two communication modes. In Experiment 2, 17 groups of 4 in each of the CMC and FTF condition discussed a college-based university system for an hour. Then group members rated each other on another five trait dimensions. Although ratings of others were more positive in FTF than CMC condition, there no systematic differences in two types of agreement and meta-accuracy between the two communication modes. In Experiment 3, 17 groups of 4 in each of the CMC and FTF condition discussed a donation entrance system for an hour and then group members rated each other on five trait dimensions different from those used in Experiment 1 and 2. The findings replicated Experiment 1. Study 2 examined gender differences in person perception in CMC. Fifteen dyads for each of the man-man, man-woman, and man-woman conditions communicated for an half hour in CMC and then rated each other along with self ratings on 25 personality trait dimensions. Results indicated that participants rated their partners more negatively for extorversion, agreeableness and culture factors, which was due mainly to woman's negative evaluations for their male partners. Also, self-peer agreement was the largest in the man-man communication condition. These findings were discussed in relation to differences between CMC and FTF communication modes.

• Journal of Korean Elementary Science Education
• /
• v.31 no.4
• /
• pp.481-489
• /
• 2012

The purpose of this study was to analyze the understanding of the sighting and hearing elementary school students have through drawing. For this purpose, we conducted a questionnaire survey of 602 elementary school students. The questionnaire was composed with open-ended question developed by West et al.(2008). This questionnaire was presented only appearance of face. And let them express the sensory pathway by drawing and writing. The students' responses for questionnaire were classified by 5 levels. Inner-researcher consistency was 0.89, inter-researcher consistency was 0.83. The data analyzed were ${\chi}^2$ by using SPSS. The result of this study were as following: First, elementary school students have misconception of sighting and hearing. There were no difference among the grade. In spite of becoming upper grade, students have still misconception. Second, scientific concept that male students have were significantly more than female. Third, the concepts of the anatomically organs are more exposed in real-life situations, students known better. Within these results, it would be used for developing teaching-learning strategies which can use misconceptions students have.

• Electronics and Telecommunications Trends
• /
• v.35 no.6
• /
• pp.137-149
• /
• 2020

Several multi-agent reinforcement learning (MARL) algorithms have achieved overwhelming results in recent years. They have demonstrated their potential in solving complex problems in the field of real-time strategy online games, robotics, and autonomous vehicles. However these algorithms face many challenges when dealing with massive problem spaces in sparse reward environments. Based on the centralized training and decentralized execution (CTDE) architecture, the MARL algorithms discussed in the literature aim to solve the current challenges by formulating novel concepts of inter-agent modeling, credit assignment, multiagent communication, and the exploration-exploitation dilemma. The fundamental objective of this paper is to deliver a comprehensive survey of existing MARL algorithms based on the problem statements rather than on the technologies. We also discuss several experimental frameworks to provide insight into the use of these algorithms and to motivate some promising directions for future research.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.10
• /
• pp.3397-3406
• /
• 2012

Three types of spherulitic morphologies have been investigated in dual substrate mode of Belousov-Zhabotinsky (BZ) type reaction system. Prior to growth of spherulites, three distinct patterning behaviors have been observed sequentially during the reaction process. Initial and the early-phase of reaction showed the emergence of concentric ring-like wave patterns. A colloidal-state of reaction consists of numerous fine solid particles, which forms primarily some nucleation centers of dendritic characters. The nucleation centers were found to grow in sizes and shapes with the progress of reaction. It leads to growth of dendritic-like spherulitic crystal patterns. The resultant spherulites showed transitions in their morphologies, including sea-weeds and rhythmic spherulitic crystal patterns, by the effects substituted organic substrate and in the higher concentration of bromate-initiator respectively. The branching mechanism and crystal ordering of spherulitic textures were studied with help of optical microscope (OPM) and scanning electron microscope (SEM). Characteristics of crystal phases were also evaluated using X-ray diffraction (XRD) and differential thermal analysis (DTA). Results indicated that the compositions of reactants and crystal orderings were interrelated with morphological transitions of spherulites as illustrated and described.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.637-640
• /
• 2005

In the development of a electronic system for a optical payload comprising mainly EOS(Electro-Optical Sub-system) and PDTS(Payload Data Transmission Sub-system), many aspects should be investigated and discussed for the easy implementation, for th e higher reliability of operation and for the effective ness in cost, size and weight as well as for the secure interface with components of a satellite bus, etc. As important aspects the interfaces between a satellite bus and a payload, and some design features of the CEU(Camera Electronics Unit) inside the payload are described in this paper. Interfaces between a satellite bus and a payload depend considerably on whether t he payload carries the PMU(Payload Management Un it), which functions as main controller of the Payload, or not. With the PMU inside the payload, EOS and PDTS control is performed through the PMU keep ing the least interfaces of control signals and primary power lines, while the EOS and PDTS control is performed directly by the satellite bus components using relatively many control signals when no PMU exists inside the payload. For the CEU design the output channel configurations of panchromatic and multi-spectral bands including the video image data inter face between EOS and PDTS are described conceptually. The timing information control which is also important and necessary to interpret the received image data is described.

• Korean Journal of Materials Research
• /
• v.9 no.2
• /
• pp.199-204
• /
• 1999

As the engine design change to get high efficiency and performance of commercial diesel engine, surface wear of the cam follower becomes an important issues as applied load increasing at the contact face between cam follower and cam. Purpose of this study is the developing of the ceramic cam follower made of silicon nitride ceramic which is more wear resistant than the cast iron and sintered cam follower. Ceramic cam follower was made by direct brazing of thin ceramic disk to steel can follower body using active bracing alloy. Effect of joining condition on the interfacial phases and joining strength wer examined at bvarious joining temperatures, times, and cooling rates. Crowning resulted from the difference of thermal expansion coefficient after direct brazing without using any stress-relieving inter layer was measured. Interfacial phases are mainly titanium silicide and titanium nitride which are the products between active metal(Ti) in brazing alloy and silicon nitiride. Maximum joining strength of the ceramic metal joint, measured by DBS method, was 334MPa. Crowning(R) of the prototype ceramic cam follower was 1595mm. As machining for crowning is not necessary, production cost can be reduced.