• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.1227-1230
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• 2005

최근 다양한 네트워크의 융합(Convergence) 추세에 따라 기존 PSTN 서비스도 인터넷에서 VoIP 형태로 제공이 되고 있다. 하지만 VoIP 서비스는 인터넷망을 이용하므로 부여된 발신번호 정보를 송출하지 않아 발신자의 위치 및 해당지역의 공공구조기관(PSAP)의 식별이 불가능하여 긴급서비스 지원을 위한 위치정보 제공을 못하는 문제점이 제기되었다. 최근 측위기술의 활용이 다양해지고 요구수준이 높아짐에 따라 실내에서의 신호 차폐 문제점을 극복할 수 있고, 높은 위치정확도 등을 제공하는 WLAN와 RFID 기술을 이용한 측위기술 연구가 활발하다. 따라서 본 논문에서는 Wi-Fi, RFID, GPS를 이용한 측위기술을 사용하여 무선이동통신 환경에서 VoIP 긴급서비스를 지원하기 위한 모델 제안과 각 구성요소에 대한 기능, 세부적인 지원 절차를 설명하고, 위치정보의 획득 및 처리를 위한 운용 시나리오에 관한 구체적 방안과 제안모델을 적용하기 위한 고려사항에 대한 분석결과를 제시한다. 그 결과 제안된 모델은 무선이동통신의 긴급서비스 설계시 적용이 기대된다.

• Restorative Dentistry and Endodontics
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• v.15 no.2
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• pp.127-133
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• 1990

Electronic working length determination is based on the electrical impedence between the root canal and the periodontal ligament Different canal irrigants with different electric conductivity may effect on the accuracy of the electronic mechanism. 0.9% Saline, 2.5% NaOCl and 3% $H_2O_2$ were evaluated either in wet or in dry condition. The results were as follows. 1. The electrical resistance mearured by Impedence Meter (Model #253, portland, USA) were 1 $K{\Omega}$ in 0.9% Saline, 0.1$K{\Omega}$ in 2.5% NaOCl and 48 $K{\Omega}$ in 3% $H_2O_2$. 2. Saline measured -0.57mm from the actual canal length and had significant difference. When dried with paper points, however, it measured -0.25mm demonstrating no statistical difference. 3. 2.5% NaOCl measured -4.07mm in wet and -2.26mm in dry condition and both showed significant difference from the actual canal length. 4. 3% $H_2O_2$ measured +0.02mm in wet and -0.09mm in dry canals and both appeared to be within acceptable range for the electronic working length mechanism.

• Restorative Dentistry and Endodontics
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• v.11 no.1
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• pp.53-61
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• 1985

This study was conducted to evaluate and compare the apical leakage in the following retrograde techniques; apicoectomys, retrograde filling with zinc oxide eugenol cement, non-zinc and zinc amalgam, and cold-burnished gutta-percha method. One hundred twenty five upper anterior and lower premolar teeth were divided into five above mentioned groups and each tooth was individually prepared for its particular group. The specimens were incubated at $37^{\circ}C$ for 14 days and then were infiltrated by 2% methylene blue for 24 hours. The apical leakage was evaluated by measuring the degree of dye penetration between the filling material and the canal wall. The results were as follows: 1. The cold-burnished gutta-percha group showed the least amount of apical leakage and the apicoectomy group showed the greastest amount of apical leakage. 2. Statistics showed that there were significant differences among the groups (P<0.05), however there was no difference between the zinc oxide eugenol cement retrograde filling group and the non-zinc amalgam retrograde filling group (P>0.05).

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.399-402
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• 1997

It is important to find a accurate root canal length or successful endodontic therapy. By X-ray method takes a long time and difficult in a curved canal. After developed electronic apex locator has allowed to measure the root canal length with easy, in a short time also in a curved canal. But most electronic apex locators have the disadvantage which is too short reading or sometimes the measurement itself becomes impossible if there are electrolytes in the canal. To overcome this drawback, impedance ratio method has been developed. In this study, we have developed frequency dependent electronic apex locator to minimize the interference of electrolytes. And based on that also some error in clinic use, we added the other method. Difference of two signals which are used in calculation of impedance ratio was can be represent the status of root canal fluid. As a result, using impedance ratio method and auto-calibration by voltage difference method can reduce the measurement error.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.4
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• pp.349-355
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• 2019

Reproductive ecology of rabbit fish, Siganus fuscescens were investigated from samples collected monthly in the coastal waters off Jeju Island of Korea from February to December 2014. In male and female of S. fuscescens, the values of GSI were reached high values between July to August in which the water temperature was high, and then decreased until December. The occurrence of individuals which have mature eggs in ovary were higher from July to August. Therefore, a main spawning season was estimated from July to August, with the highest peak in July. Throughout histological observation of the ovary in the spawning period, S. fuscescens belong to an group-synchronous and has a one spawning season a year. Fecundity of ovary ranged from 380,000 to 2,600,000 during the spawning period. Size at 50% sexual maturity, determined from logistic equation, were 25.1 cm TL which is over two years.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.2
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• pp.99-107
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• 2011

The relationships among long-term variation in catches of Spanish mackerel (Scomberomorus niphonius) and main food organism such as common mackerel (Scomber japonicus), anchovy (Engraulis japonicus), and oceanic condition in Korean waters were analyzed using 40 years of time-series data from 1971－2010. In the 1990s, oceanic conditions around the Korean peninsula shifted to a warmer regime with higher SST (sea surface temperature). The total catch of Spanish mackerel in Korean waters increased dramatically since the early 2000s, and main fishing ground form into South Sea in winter season from December to January. From the results of correlation analysis, we found a significant relationship between the Spanish mackerel catch and environmental factor such as SST, common mackerel and anchovy catch in Korean waters.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.2
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• pp.169-175
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• 2014

The age and growth of rabbit fish, Siganus fuscescens were investigated from samples monthly collected in the coast of Jeju island, Korea from February to December 2012. Ages were determined from annuli in otoliths, and annuli were formed in one or two months immediately after spawning once a year. Also, main spawning period was estimated between July and August, thus rings were considered as annual marks. The von Bertalanffy growth equations estimated from a non-linear regression method were $L_t=37.24(1-e^{-0.33(t+1.24)})$ ($R^2=0.92$) for female and $L_t=31.44(1-e^{-0.45(t+1.23)})$ ($R^2=0.90$) for male, and the growth between female and male was different.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.575-595
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• 1997

Replacement resorption is followed by the delayed replantation of an avulsed tooth. Currently no effective treatment is substantiated for replacement resorption. The purpose of this study was to investigate the effect of stannous fluoride, bisphosphonate (etidronate disodium) and gallium nitrate, which have been shown to reduce dentin resorption, on human dentin. Osteoclasts were collected from tibeas of chick embryo. The cells were well agitated to prevent adhesion and seeded onto the sliced human dentin wafers which had been soaked in either culture media (control), or several different concentrations of stannous fluoride, etidronate disodium (l-hydroxyethylidene -1,1-bisphosphonate disodium), and gallium nitrate. Resorption was measured by counting the number of resorptive pit produced by the cells. Results are as follows. Stannous fluoride and etidronate disodium showed statistically significant reduction of dentin resorption(p<0.05) but the effect of stannous fluoride seemed to be its high cytotoxicity. Etidronate disodium did not show cytotoxicities in all experimented concentrations. Gallium nitrate did not show differences in resorption either between different concentrations or from the control group.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.809-819
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• 1997

The purpose of this study was to develop an accurate frequency-dependent type apex locator. To compensate the impedence differences of different canal contents, voltage differences were pre-measured and stored for saline, HOsb1/$2O_2$ and NaOCl. The circuit was adjusted to recognize the different voltages of each solution, thereby the machine could automatically compensate the voltage differences. In the process of this study, the following informations were observed. 1. Most stable apical reading was obtained at 500Hz and 10kHz. 2. There were no differences in accuracy among three different frequency types, sign wave, triangular wave and rectangular wave(p>0.05). 3. Before the compensation of voltage differences, saline, H2O2 and NaOCl showed different readings at the apex even with the frequency-type (p<0.05). 4. After compensating the voltage difference, the accuracy was enhanced from + 0.42 to +0.32 in H2O2(p<0.05), from -0.34 to -0.12 in NaOCl(p<0.05).

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.731-738
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• 1997

A retrospective in vivo study of endodontically treated mandiblar molars was conducted. The radilographs and clinical records of mandibular molars that had been treated endodontically in the Dental hospital of Yonsei University from 1986 to July 1997 were reviewed and categorized. A total of 1751 cases were studied and following results were obtained. 1. The number of root canals in mandibular first permanent molar in a Korean population revealed three in 53.2 %, four in 23.0 %, two in 18.4 %, C-shaped canal in 5.0 %, and one in 0.4 %. 2. In mandibular second molar, three canals was observed in 53.2 %, four in 22.2 %, two in 14.9%, C-shaped canal in 9.1 %, and one in 0.6%. 3. In the results of the percentage of 4 canals of mandibular first molars at various age, before age 20, 37.7 % was obtained whereas 19.3 % after 30. 4. 7.94 % of mandibular first molars examined were found to have three roots. 5. The mandibular second molar had C-shaped canals in 9.1 %.