• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.27-32
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• 2008

The present study has been conducted economic analysis of heat storage type ground source heat pump system(HSGSHP) and normal ground source heat pump (GSHP) which are installed at the same building in the shared an apartment house. Cost items, such as initial cost, annual energy cost and maintenance cost of each system are considered to analyze life cycle cost (LCC) and simple payback period (SPP) with initial cost different are compared. The initial cost is a rule to the Government basic unit cost of production. LCC applied present value method is used to assess economical profit of both of them. Variables used to LCC analysis are prices escalation rate and interest rate mean values of during latest 10 years. The LCC result shows that HSGSHP (1,050,910,000won) is more profitable than GSHP by 68.9% initial cost. And SPP appeared 3.0 year overcome the different initial cost by different annual energy cost.

• Korea journal of population studies
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• v.17 no.2
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• pp.116-135
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• 1994

China's population and family planning program has heen successful. Women's fertility as measured by total fertility rate (TFR) has declined from 5.8 in 1970 to 2.3 in 1990, accordingly the annual crude birth rate(CBR) has declined from 34 per thousand in 1970 to 21 per thousand in 1989, and the annual natural growth rate from 2.6 percent in 1970 to 1.4 percent in 1989 (Coale and Chen, 1987; SSB, 1991; Gu, 1994). While this is indeed an astonishing achievement for a developing country to have its fertility down to replacement within a short period, some new issues emerging along with the rapid fertility decline require careful considerations. One of them is the uprising of the sex ratio at birth in China. The 1990 population census reported the sex ratio at birth in China of 113.8 in 1989, which is ohviously much higher than the acceptable level of normal ratio around 106. It has received since then a lot of tention in China and abroad, among demographic professionals and governmental agencies alike (Hull, 1990; Johansson and Nygren, 1991; Xuand Guo, 1991; Tu, 1993; Gu and Xu, 1994; among others). Based on the available demographic data and research results this paper will first have a review of the patterns and trends of sex ratio at birth in China, then turn to the immediate causes of abnormal sex ratio at birth and the determinants of the son preference, followed with a conceptual framework for understanding of the phenomenon, and finally the policy implications and recommendations will be discussed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.5
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• pp.93-103
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• 2009

Since message forgery or alteration in VANET may cause severe consequences, authentication of critical messages must be provided. However, using normal digital signature may infringe privacy of drivers. Therefore, VANET requires authentication systems that provide conditional anonymity. In this paper, we propose a new authentication system for VANET. In our proposed system, each vehicle can update its pseudonym using re-encryption technique and digitally sign messages using representation problem on the pseudonym. By limiting the usage period, revocation of individual pseudonym is not required. Moreover, we also provide a way to revoke the vehicle itself. Secureness of our system partially rely on the usage of tamper-resistance hardware.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.927-932
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• 2022

Instrument drift is caused by the passage of time, environmental changes, normal wear and tear, debris buildup, sudden shock, vibrations, electromagnetic fields, and improper use. Since it is inappropriate to directly determine the change of the output value as drift during the limited test period, a new algorithm that reflects both zero drift and span drift by giving changes over time to the calibration method of the instrument was proposed. The temperature drift was calculated to be 0.49% for about 60 minutes at 1-minute intervals in the nine-step constant temperature environment through the warming and cooling process.

• Communications for Statistical Applications and Methods
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• v.30 no.2
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• pp.163-178
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• 2023

GARCH-X(1, 1) model specifies that conditional variance follows an AR(1) process and includes a past exogenous variable. This study proposes a new class from that model by allowing a more general (non-linear) variance function to follow an AR(1) process. The functions applied to the variance equation include exponential, Tukey's ladder, and Yeo-Johnson transformations. In the framework of normal and student-t distributions for return errors, the empirical analysis focuses on two stock indices data in developed countries (FTSE100 and SP500) over the daily period from January 2000 to December 2020. This study uses 10-minute realized volatility as the exogenous component. The parameters of considered models are estimated using the adaptive random walk metropolis method in the Monte Carlo Markov chain algorithm and implemented in the Matlab program. The 95% highest posterior density intervals show that the three transformations are significant for the GARCHX(1, 1) model. In general, based on the Akaike information criterion, the GARCH-X(1, 1) model that has return errors with student-t distribution and variance transformed by Tukey's ladder function provides the best data fit. In forecasting value-at-risk with the 95% confidence level, the Christoffersen's independence test suggest that non-linear models is the most suitable for modeling return data, especially model with the Tukey's ladder transformation.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.3
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• pp.337-346
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• 2022

This study explores the impact of the COVID-19 pandemic on the stock prices of state-owned enterprises listed on the Indonesia Stock exchange. The impact of the pandemic is analyzed based on different pandemic phases and the corresponding government pandemic interventions to curb the disease. This study analyzes 6 pandemic event dates, covering the time period from January 2020 to February 2021. A total of 20 state-owned enterprises are included as the sample of this study. Test of difference is employed to compare the stock prices of the state-owned enterprises before and after each pandemic event date. In general, this study confirms the adverse impact of the COVID-19 pandemic on the stock prices, especially the event in 2020, although some variations do exist. The results of the study reveal a significant decrease in the stock prices of the state-owned enterprises after the announcement of the first confirmed COVID-19 cases, the announcement of COVID-19 as a global pandemic, the imposing of Large Scale Social Restriction (PSBB I and PSBB II). In contrast, the stock prices increase after the imposing of a new normal policy and the imposing of Public Activity Restriction (PPKM). This study also documents that the effect of the pandemic may vary based on the pandemic phase.

• Journal of Distribution Science
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• v.22 no.1
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• pp.47-59
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• 2024

Purposes: The study aimed at examining the impact of the COVID-19 pandemic on the shift of online consumer purchasing behavior and whether the new behaviors would be maintained after the epidemic season. The study also aims to investigate how online customers change based on perceived risks. Research design and Methodology: The study investigated purchasing behavior of the same 377 online Vietnamese consumers during two periods: (1) during the period of social distancing and (2) one and half year after that, allowing data to be collected in real time, so that consumers do not have to recall their behavior. Results: Purchasing behavior appeared to be more influenced by gender, age and household size. Aged consumers are more concerned about risks than those in the younger group, who only worry about the risks during the pandemic. Consumers in households with two or more people are more concerned about the risks than those living alone. Female appeared to be more influential in both during and after pandemic than male. Conclusions: The findings contribute to clarify shift of online consumer purchasing behavior, which helps business to develop effective marketing strategies and enhance their presence in the e-commerce sector.

• Asia pacific journal of information systems
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• v.32 no.3
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• pp.656-683
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• 2022

The COVID-19 pandemic has profoundly affected the world, inflicting nationwide lockdowns interrupting conventional schooling through schools, colleges and universities. Educational institutions are struggling to maintain learning continuity through remote learning solutions. Still, the students' perception of this 'new normal' mode and pace of learning needs to be examined to ensure the success of these efforts. This study aimed at examining the perception of higher education students in India and Croatia especially with respect to the association between cultural orientation and the e-learning. The period considered for the data collection was from March 2020 to September 2020. Correspondence analysis was attempted to create spatial maps to depict the respondent choices. Students from both the regions agreed to the high-power distance that existed in their cultures and considered the role of device and content to be an important dimension of e-learning for it to be effective, but the results also pointed out some differences in their choices on other culture dimensions as well as factors affecting e-learning which make this study unique and suggest in-depth future research for conclusive results.

• The Korean Journal of Mycology
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• v.9 no.4
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• pp.199-207
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• 1981

This investigation was undertaken to establish more accurately the clinical features of the desease as seen in Korea, and to investigate susceptibility factors and to study the ecology of P. orbiculare in this condition. All of 50 new patients with Tinea versicolor attending the Ewha University Hospital, during a period of 6 months were studied personally. 1. Clinical feature: The sex ratio of the whole series was 32 males to 18 females. Twenty of 50 patients (40%) were between the age of 20 to 29 years. The duration of disease was more than 4 months in 37 of 50 patients (74%). The cases of first onset in June, July and August were 33 of 50 patients (66%). Whereas, the developed in December, January and February were only 3 of 50 patients (6%). Seasonal fluctuation was remarkable in 16 of 25 patients (66.7%) who had the duration of more than 1 year. The course of disease was rapid in 33 of 50 patients (66%) and slow in 9 of 50 patients (18%). Thirty-three of 50 patients (66%) had not any subjective symptoms. Thirteen patients (26%) had mild itching sensation and 4 patients (8%) had severe itching. The frequency of the first affected were neck (27.4%), axilla (19.2%) anterior chest (15.0%) and groin (11.0%). 7) Hyperpigmented lesions were observed in 35 of 50 patients (70%) and hypopigmented lesions were observed in 11 of 50 patients (22%). Skin lesions were noticed mainly in the anterior chest, neck, back and axilla, and more severe in the anterior chest, back and abdomen than other areas. Tinea versicolor was particularly prevalent in those persons who had occupations of mental work and who perspired every day or every 2 or 3 days. A positive family history of Tinea versicolor was obtained in 7 of 50 patients (14%). Fourteen of 50 patients (28%) had association with superficial fungal infections. 2. Mycological features: Typical appearance of M. furfur was observed in all scrapings from 25 lesions and only 3 scrapings from 20 clinically skin of the patients. P. orbiculare was seen on direct examination of scrapings from 24 of 25 skin lesions, from 19 of 20. clinically normal skin of patients and from 18 of 29 control normal skin. The quantity of P. orbiculare was greater in skin lesions and clinically normal skin area than in control normal skin surfaces.

• Journal of Oral Medicine and Pain
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• v.31 no.2
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• pp.141-146
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• 2006

Personality characteristics of recurred TMD patients were analyzed psychologically by using the SCL-90-R. 27 recurred TMD patients, 45 new TMD patients, control I were subjected at Orofacial pain clinic, Department Of Oral Medicine and Health Promotion Center, Pusan National University Hospital during the period from 2005 to 2006. 50 general dental patients, control II were subjected at a local dental office in Pusan during the same period. The obtained results were as follows. 1. Mean values of T-scores on 9 basic scales in all the groups were within normal range. 2. The T-scores of IS, Dep, Phob, Psy in general Dental patient group were significantly higher than those in recurred TMD patient group. 3. As compared with recurred TMD patient Group & control I group by sexual subclass, there was no significant difference of the scales. 4. As compared with acute and chronic groups, there was no significant difference of the scales in recurred TMD patient group. However, the T-scores of Som, Par, Phob, Psy in chronic new TMD patient group were significantly higher than those in acute new TMD patient group, control I group.