• Journal of the Korea Society for Simulation
• /
• v.21 no.2
• /
• pp.69-78
• /
• 2012

In this paper, a study on finding an appropriate helper node that can help increase effective frame transmission rate for cooperative communications at ad hoc networks is carried out. Those researches from reference use the reactive helper node selection mechanism which starts its role after exchanging RTS and CTS frames between source and destination nodes, and are implemented into our simulator for performance comparison. System throughput and average channel access delay are used for performance measures and all communicating nodes are assumed to move independently within the communication range. It is anticipated that this research result can be used as basic information for designing a new efficient helper node selection scheme.

• Physical Therapy Korea
• /
• v.11 no.1
• /
• pp.27-34
• /
• 2004

This study aims to compare the relationship between the Berg Balance Scale (BBS) scores, Timed Up & Go (TUG), Functional Independent Measure (FIM), and subject characteristics. All of the 18 subjects were women between the ages of 68 and 91 (mean=80.2, SD=5.43), and they all lived at the nursing home in Wonju. Balance was measured using BBS, and functional mobility was measured using TUG. FIM was used to evaluate functional independence. Data were analyzed using Spearman correlation. Statistically significant differences were noted between BBS and TUG (r=-.486, p<.05). There were no significant statistical differences between total FIM and BBS, TUG. The FIM items "locomotion" and "communication" showed significant statistical differences between BBS and TUG. The results suggest that FIM may be able to predict dangerous falls in elderly people.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.8
• /
• pp.2106-2112
• /
• 1999

In decision-making, information is the thing manufactured as the useful type for decision -making. We can improve the efficiency of decision-making by elimination of unnecessary information. Rough set is the theory that can classify and reduce the unnecessary. But the reduction process of rough set becomes more complex according to the number of attribute and tuple. After eliminating of the dispensable attributes using $\chi$2 and rough set, the indispensable attributes are used for the units of input layers in neural network. This rough-neural network can support more correct decision-making of neural network.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.1136-1137
• /
• 2006

통합항해시스템이라 함은 자동화된 선박의 운용에 관한 것으로, 다양한 항해 센서(GPS, Gyro, Speed Log, echo sounder)를 이용하여 선박의 항해에 필요한 각종 정보를 입수하여 최적의 항로를 설정해주고, 운항의 안정성과 효율을 극대화시키는 시스템을 지칭한다. 즉, 선박의 운항에 필요한 다수의 모듈들을 독립적으로 운용하는 것이 아니라 이를 통합된 형태로 운용하여 효율을 극대화시키는 시스템이 통합항해시스템이라 할 수 있다. 통합항해시스템은 다양한 항해 센서들과 항해 시스템으로 구성되며, 다양한 항해 데이터들은 항해 센서로부터 수신하여 처리하는 동작을 수행한다. 즉, 통합항해시스템은 다수의 센서들로부터 수신된 정보를 평가하고 잠재적 위험과 무결성 저하에 대해서는 적절한 경고를 제공하여야한다. 따라서, 항해센서 데이터의 유효성(Validity) 및 모호성(Plausibility) 검사와 무결성 감시(Integrity Monitoring)는 통합항해시스템의 필수적 기능이라 할 수 있다. 본 연구에서는 IEC 61924 규격에 의한 항해센서로부터 수신된 항해데이터가 정확하고 유효함을 가지는 지에 대한 가치평가의 척도와 독립적인 데이터 소스로부터 데이터를 비교하여 검증하는 무결성, 정확도 이내의 정보를 완전하고 명확한 방법으로 사용자에게 제공하는 무결성 감시의 방법을 제시하며, 항해센서들에 의해 취득되는 항해 데이터의 무결성 검사를 통한 유효성, 적용가능성, 무결성의 평가방법을 기술한다.

• The Journal of Korean Association of Computer Education
• /
• v.14 no.5
• /
• pp.97-104
• /
• 2011

Collaborative filtering is a methodology to recommend websites by obtaining data and opinions from the other users with similar tastes. During the past few years, this method has been used in various fields such as books, food, and movies in e-commerce systems. This study addresses the computation of similarity between users to determine items to be recommended in collaborative filtering systems. Previous studies measured similarity between users by treating each user's ratings independently without considering the distribution of the user's ratings. In contrast, this study measures similarity by utilizing position and rank information of each rating in the range of the user's ratings. The result of the experiments on the real datasets demonstrated that the proposed method improves the mean absolute error significantly, compared to the previous methods, especially when the predetermined range of ratings is large.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.7
• /
• pp.1380-1386
• /
• 2003

Speech recognition performance is degraded by the variation in vocal tract length among speakers. In this paper, we have used a vocal tract length normalization method wherein the frequency axis of the short-time spectrum associated with a speaker's speech is scaled to minimize the effects of speaker's vocal tract length on the speech recognition performance In order to normalize vocal tract length, we tried several frequency warping functions such as linear and piece-wise linear function. Variable interval piece-wise linear warping function is proposed to effectively model the variation of frequency axis scale due to the large variation of vocal tract length. Experimental results on TIDIGITS connected digits showed the dramatic reduction of word error rates from 2.15% to 0.53% by the proposed vocal tract normalization.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.14 no.3
• /
• pp.73-84
• /
• 2019

Despite decades of work experience, workers at small- and medium-sized enterprises(SME) here have yet to make inroads into the self-employed sector that utilizes the job competency they have accumulated at work after retirement. Unlike large companies, SME do not have a proper system for improving the long-term job competency of their employees as they focus on their immediate performance. It is necessary to analyse the independent variables affecting the job competency of employees of SME to derive practical implications for the personnel of SME. In the preceding studies, there are independent variable analyses that affect job competency in specialized industries, such as health care, public officials and IT, but the analysis of workers at SME is insufficient. This study set the person-job fit and organizational justice based on the prior studies of the independent variables that affect the job competency of SME general workers as a dependent variable. The sub-variables of each variable derived knowledge, skills, experience, and desire for person-job fit, and distribution, procedural and deployment justice for organizational justice, respectively. The survey of employees of SME in Korea was conducted from February to March 2019 by Likert 5 scales, and the survey was retrieved from 323 people and analyzed in a demonstration using the SPSS and AMOS statistics package. Among the four sub-independent variables of person-job fit, knowledge, skills and experience were shown to have a significant impact on the job competency, and desire was not shown to be so. Among the three sub-independent variables of organizational justice, deployment justice has a significant impact on job competency, but distribution and procedural justices have not. Personnel managers of SME need to improve the job competency of their employees by appropriately utilizing independent variables such as knowledge, skills, experience and deployment at each stage, including recruitment, deployment, and promotion. Future job competency modeling studies are needed to overcome the limitations of this study, which fails to objectively measure job competency.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.16 no.1
• /
• pp.79-89
• /
• 2005

Objectives : To acquire an improved understanding of oppositional defiant disorder, we evaluated the characteristics of children who have the symptoms of ODD in community sample. Methods : 1200 children from an elementary school in Bucheon (an urban community near Seoul) were recruited by randomized sampling method. By Disruptive Behavior Disorder Scale according to DSM-III-R & DSM-IV, we evaluated the symptoms of ODD and selected subjects with ODD. Psychiatric comorbidity, character trait were compared in subjects with ODD and comparison group. Also we examined the association between prenatal/perinatal risk factors, family functions and the symptoms of ODD. Data were analyzed by appropriate statistical method using SPSS 11.5 window version. Result : Children with oppositional defiant disorder were revealed to have significantly higher rates of psychiatric comorbidity and significantly greater family dysfunction compared to comparison group. Among the prenatal/perinatal risk factors, severe emotional stress during pregnancy, postpartum depression, medication during pregnancy were revealed as risk factors of ODD. In character inventory, ODD group were evaluated to have high score in novelty seeking, harm avoidance, but low in reward dependency. Conclusion : These results support that 1) prenatal/perinatal and psycho-social risk factors could be a important role in the progression of ODD, and 2) children with ODD have diverse comorbid psychiatric symptoms.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.16 no.2
• /
• pp.199-210
• /
• 2005

Objective : Attention deficit hyperactivity disorder(ADHD) affects $5-10\%$ of children in Korea, with more boys and girls being diagnosed. Despite seriousness of ADHD, little is known about its causes. From the current genetic epidemiologic studies, ADHD is known as a heritable disorder. Till now, however, there have been very few genetic studies about ADHD in Korea. The aim of the this study is to examine the association between dopamine transporter gone type 1 and ADHD using case-control design in Korean ADHD probands and normal controls. Materials and Method : Child Psychiatric Genetic research team in Seoul National University Hospital, Clinical Research Institute recruited the ADHD probands using clinical interview/observation, diverse rating scales, and neuropsychological tests. For eliminating phenocopy or ADHD, diagnosis of ADHD was based upon clinical data, psychometric data, and parent/teacher reports. Total 85 ADHD-probands were recruited as final study subjects and independent 100 normal adults participated in this study as control group. For all the ADHD probands, and controls, the 3'-UTR-VNTR polymorphism of DAT1 was analyzed. Based on the DAT1 allele and genotype informations, Chi-square test based on case-control design was performed. Results : As for genetic study, total of 85 probands and 100 controls were included for the genetic analysis. Four different alleles, 350bp (7repeat), 440bp (9repeat), 480bp (10repeat) and 520bp (11repeat) were found in DAT1 gene of study subjects. In case-control analysis, ADHD probands and parents have significantly more 9 repeat allele and 9/10 genotype. Also, The probands with 9repeat allele have more commission errors in ADS. Conclusion : The positive association between ADHD and DAT1 gene was replicated in this report like other previous results for caucasian children and Korean children with ADHD. There are ongoing studies on other candidate genes such as DRD4 and DRD5 and it would be required to explore the association of these candidate genes in Korean children with ADHD. These ongoing genetic research will contribute to the understanding of heterogenous genetic and environmental etiologies of ADHD phenotype, which will lead to the development of more comprehensive treatment and preventive interventions for ADHD.

• Sleep Medicine and Psychophysiology
• /
• v.16 no.2
• /
• pp.85-90
• /
• 2009

Introduction: There has been an increasing interest in the relationship between sleep and suicidality. In addition, suicidal patients habitually report their sleep problems. Although sleep-related complaints and electroencephalographic changes are generally encountered in psychiatric disorders, sleep complaints such as insomnia, hypersomnia and nightmares are more common in suicidal patients. In current study, we aimed at investigating the relationship between self-reported sleep duration and suicidality in general population. Methods: One thousand general population (male:female=500:500, mean age=$39.6{\pm}11.6$ years, ranged age=20-77 years) completed Center for Epidemiologic Study-Depression (CES-D), Beck Suicide Intent scale (BSI), Spielberger State-Trait Anger Expression Inventory (STAXI), Barratt Impulsiveness Scale (BIS), Morningness-Eveningness Scale (MES) and brief questionnaire of sleep habits. Results: After controlling for age and sex, score of BSI was correlated positively with the score of CES-D, STAXI and BIS on partial correlation analysis ($r_p$=0.251; p<0.001, $r_p$=0.352; p<0.001, and $r_p$=0.175; p<0.001, respectively). In addition, score of BSI was inversely correlated with the score of MES (rp=-0.066; p=0.037). However, score of BSI showed no significant correlation with sleep duration. However, regression analysis revealed that short (<6 hrs) or long (>10 hrs) sleep duration, the family history of psychiatric illness, the score of CES-D, and the score of STAXI predicted higher score of BSI significantly in total subjects (F=17.837, adjusted $R^2$=0.166; p=0.003, p=0.003, p<0.001, and p=0.003, respectively). This model was explained better in depressed subjects with 16 or higher score of CES-D (F=9.920, adjusted $R^2$=0.298). Conclusion: Current result suggested that not only short sleep duration (<6 hrs) but also long sleep duration (>10 hrs) might be related to suicidality.