• Journal of Korean Association for Spatial Structures
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• v.7 no.2 s.24
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• pp.105-114
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• 2007

Large span spaces have been widely used for various purposes including sports events in other countries. Due to increasing demands on multi-purpose use of such spaces, recently built large span sport facilities such dome stadiums have been required to accommodate sport events as well as performing events. Also, retractable ceilings and/or walls were generally adopted in those spaces for providing various event conditions. It seems obvious that the openings between diffuse fields and free field may cause difficulties in the acoustic design of such spaces In the present work, the acoustic characteristics of non-diffuse field has been investigated using 1/10 acoustic scale models. It was found that RTs at low- and mid-frequencies decayed faster than those at high-frequencies as the percentage of opening area increased. The decay rate of RTs at high frequencies were not influenced by increasing the area of an opening. Also high dependence of EDT on the percentage of opening area was observed at all frequency range. D50 was not improved by increasing the area of an opening up to 12.5% and then sharply increased. The application of Schroeder integration to evaluate the reverberation charateristics of coupled spaces may not be proper, since non-exponential decay process with double or triple decays of those spaces can not be properly defined. EDT seems more appropriate to predict reverberation at the early acoustic design stage of acoustically coupled spaces.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.4
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• pp.121-131
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• 2017

The most important points in the field of entrepreneurship research are new venture creation and behaviors for start-up venture. Most of past researches are limited to the formation of entrepreneurial intention, and researches on entrepreneurial activities, specifically nascent entrepreneurial behavior, have not been studied well. In this study, we view entrepreneurial process as gestation process from entrepreneurial intention to nascent entrepreneurial activities, and identify the moderating effects of cognitive style, which is the way of thinking about the information in entrepreneurial process. In addition, we find the moderating effects of cognitive style on the relationships between perceived barriers and support in environmental factors and nascent entrepreneurial activities. Subjects of this study are potential entrepreneurs. So we selected university students who are taking venture start-up course, conducted a survey, collected 367 questionnaires. In statistical test, we applied PLS-SEM for testing hypotheses because CB-SEM is too sensitive to test more than two moderating effects in th research model. As a result of the analysis, it was found that entrepreneurial intention, cognitive planning style, cognitive creative style, perceived support had a significant effect on nascent entrepreneurial behavior. The results of the analysis of the moderating effects of cognitive style which are the hypotheses in the research are as follows. First, the cognitive planning style did not have a significant moderating effect on the relationship between entrepreneurial intention and nascent entrepreneurial activities. Second, in the relationship between perceived barriers and nascent entrepreneurial activity, cognitive planning style did not have significant moderating effect, and cognitive creating style had significant negative moderating effect. Third, in the relationship between perceive support and nascent entrepreneurial activity, cognitive planning style had significant positive moderating effect, and cognitive creating style did not have significant moderating effect.

• Journal of Korean Association for Spatial Structures
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• v.7 no.5
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• pp.75-82
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• 2007

The present work measured and analyzed changes in the acoustics of a sound field which has a retractable ceiling. An 1/20 scale model of an openable space was built and measurement was carried out by varying the opened area of a ceiling. The most widely used room acoustic and design parameters, RT, EDT, and D50 were investigated. The results suggest that the use of RT as an acoustic design parameter may not be proper in an openable space and further it is likely to mislead the initial acoustic design of such spaces. It is mainly due to the characteristics of RT in which non-exponential decay processes are linearly fitted. Early decay times were found to be decreased in proportion to increaing the ratio of opened area. D50, an index of speech intelligibility, was effectively shows the influence of openings on the acoustics. It is also found that EDT and D50 at the seats, not directly exposed to the opened part of a ceiling, were almost linearly decreased in proportion to the ratio of opened area, while little influence was found for the opening ratio larger than 40% at the directly exposed seats to the opened part of a ceiling.

• Journal of Korean Association for Spatial Structures
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• v.8 no.3
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• pp.65-73
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• 2008

The present work deals with subjective assessments to propose the objective parameter related to the subjective attribute of reverberation in the coupled room varied the aperture opening size. A 1/10 scale model was built and used for the measurements and subjective assessments. For the subjective tests, binaural impulse responses(BIRs) were measured using a dummy head and the measured BIRs were convolved with anechoic recorded music for the presentation over the headphones. The results showed that the perceived reverberation was the largest in the aperture opening size 12.5%(1.97% of mail) room surface area)and decreased with increasing the aperture opening size over 25% (3.94% of main room surface area) in the main room coupled with the secondary reverberant room. In the main room coupled with the secondary absorptive room, there was no changes in the perceived reverberation up to the aperture opening size 6.25%(0.99% of main room surface area) and it gradually decreased with increasing the aperture opening site over 12.5%. The objective parameter, T30/T15, showed a very low correlation with the perceived reverberation in the coupled room varied the aperture opening size but showed a high correlation with a new objective parameter, T30/Tbp, proposed by the authors. Because the late part decay energy more rapidly increases with increasing the aperture opening site than the early and middle part decay energy, the LDT/EDT or T3/T1 is a better quantifier to measure double slopes in the coupled room than the T30/T15.

• Journal of the Daesoon Academy of Sciences
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• v.49
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• pp.365-399
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• 2024

Tang Taizong was regarded as the emperor with the idea of cherishing the common people, paying close attention to his subjects' military service, and mobilizing of the people as recorded in Zhenguan Zhengyao (Essentials for Government), from the Zhenguan period during the reign of Tang Taizong. Contrary to the above, in reality, Li Shimin, the name of Tang Taizong, mobilized many subjects in the construction of Luoyang Palace in second capital city called Dongdu and Jiucheng Palace, a summer palace during Sui-Tang dynasty, and he requisitioned the subjects of Guannei Province and Longyou Province to install and protect provisional powers and a county in the Gaochang Kingdom. Given his antinomic behavior, the evaluation of Li Shimin as an ideal Confucian monarch should be reconsidered based on Zhenguan zhengyao and other historical records. Dividing the 19 years before Goguryeo-Tang War in 645 into two periods, from the throne to 637 and from 639-644, the subjects were burdened by the construction of Luoyang Palace and Jiucheng Palace in the former period. In the latter period, after the conquest of the Gaochang Kingdom, there was a requisition for the transport of troops and supplies to be stationed in Xizhou, a reorganized prefecture and counties in the Gaochang Kingdom territory; probably mainly limited to the provinces of Guannei and Lungyou, which were geographically close to the West Regin that is now known as Xinjiang Uygur Autonomous Region. The burden in the latter period was relatively less than in the former period. Even so, the number of households in 639, fourteenth year of Tang Taizong's reign, was only 34.1% and 26.8%, respectively, in 609, the sixth year of Sui Yangdi's reign. In this situation, Taizong's Goguryeo Invasion was not conducted in an economically situation during the early days of the Tang Dynasty.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.592-599
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• 2002

Objective : The purpose of this study was to evaluate the effects of several light curing methods and several adhesives on the microleakage of composite resin restorations in primary teeth. Materials and methods : In 150 extracted human primary anterior teeth, O-shaped cavities were prepared in the labial surface ; the cavity diameter and depth were 1.6mm. The cavities were filled with light-activated composite resin, Compoglass. Four kinds of adhesives were used. Each filling materials were polymerized with three light cure methods. The restorations were polished using Sof-Lex discs(3M Co., USA). The samples were thermocycled 1,000 times between $5^{\circ}C$ and $55^{\circ}C$ with a 1-minute dwell time. Then, they were immersed in a 2% methylene blue solution(pH 7) for 12hours. Subsequently they were sectioned labio-lingually through the center of the restoration with a diamond saw at low speed with a water coolant, and evaluated by stereomicroscopy. Microleakage analyses were done, using scores from 0 to 4. Results : Results showed the least microleakage in Compoglass group(P<0.05). There were less microleakage in SBMP group among the adhesive groups, but no significant difference was observed(P>0.05). And there were no significant differences among the groups depending on curing methods(P>0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.210-216
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• 2003

The double teeth include gemination and fusion. The congenital missing tooth is the absence of the tooth. The purpose of this study was to investigate the prevalence of double teeth and congenital missing teeth in preschool children of Iksan city. The study population consisted of 1,031 children, 569 boys and 462 girls, aged from 17 to 84 months. The double teeth possess a variety of diagnostic and treatment problems. Gemination is the partial splitting of a single bud into two distinct entities that remain joined in a Siamese twin fashion. Fusion is the joining of two buds. Both may be normal, or one may be a supernumerary tooth. Congenital missing is the absence of one or a few teeth. Twenty three(11 boys and 12 girls) of the 1,031 children had double teeth and 17(8 boys and 9 girls) exhibited congenital missing of teeth. The prevalence of double primary teeth was 2.2%. The prevalence of congenital missing teeth was 1.6%. One subject had double teeth and congenital missing tooth at the same time. Of the 17 cases of congenital missing teeth, one girl showed it in the maxilla and aye boys and six girls had them in the unilateral side of the mandible. There were no significant differences in the prevalence of double teeth and congenital missing teeth between the boys and the girls.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.576-580
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• 2003

A 7-year-old male was refered to Department of Pediatric Dentistry, Wonkwang Dental Hospital for treatment of a traumatic injury to the teeth of the maxillary anterior region of the mouth. His right central incisor presented subluxation and root fracture, the left central incisor had suffered intrusive luxation and root fracture. The initial treatment involved reposition and fixation of the teeth with 0.5mm stainless steel wire and composite resin. The patient was submitted for clinical and radiographic fallow-up. After 4 years, radiographically the right central incisor seemed to be healed by hard tissue union and showed to be indistinct fracture line, intact lamina dura. The left central incisor radiographically was healed by interposition of bone and connective tissue and showed to be distinct horizontal fracture line separating the fragments, and pulp canal obliteration. In clinical examination, the teeth showed a normal response to elective pulp test, percussion and mobility test. Pulp survival after injuries appears to be dependent upon the type of luxation injury, age of patient, stage of root development and degree of dislocation. In this case, the two teeth with incomplete root formation were suffered different type of injury by trauma and has showed different healing aspect.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.54-60
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• 2003

This study evaluated the influence of chemomechanical caries removal agent $Carisolv^{TM}$(MediTeam, Sweden) for composite resin adhesion to sound human permanent and primary dentin. The buccal/labial surfaces of 80 permanent molars and 80 primary incisors were used. Four types of adhesives and one composite resin were used; AQ Bond(Sun Medical, Japan), Clearfil SE Bond(Kuraray, Japan), Single Bond(3M, USA), Scotchbond Multi-Purpose(3M, USA) and Z100(3M, USA). One drop of $Carisolv^{TM}$(MediTeam, Sweden) was pretreated on the dentin for 0 second(control) and 60 seconds. The specimens were thermocycled for 1,000 times in baths kept 5 degrees C and 55 degrees C with a 30 seconds dwell time. Shear bond strengths were tested and the data was statistically analyzed using one-way ANOVA with subsequent post hoc Scheffe test at p<0.05. $Carisolv^{TM}$ treatment significantly decreased the shear bond strength. Shear bond strength of permanent dentin was significantly higher than that of primary dentin. Clearfil SE Bond treatment groups showed the highest shear bond strength and AQ Bond treatment groups showed the lowest shear bond strength.