• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.772-781
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• 2016

This study is to set the objective criteria on maxillary incisors shade selection by using the colorimetric Shade-Eye NCC as measuring in CIE $L^*$, $a^*$, $b^*$ values, and look into the meaning by analyzing its values. We explain the purpose of this study and gotten their agreement from patients visiting the dentist, 111 people's (men 50, women 61) three teeth, the maxillary central incisor, maxillary lateral incisor, maxillary canines, total of 333 teeth colorimetry. As a result of comparing the differences in colors between cervical margin and incisal edge, ${\Delta}E^*$ of canine is shown as low as $5.81({\pm}2.98)$, followed by lateral incisor of maxilla as $6.51({\pm}3.23)$ and central incisor of maxilla $7.51({\pm}3.04)$. Females show higher luminosity(L*) than males do in all teeth- central incisor, lateral incisor and canine; in yello chroma(b*) males' central incisor is slightly higher than that of females (p<0.05). Age significantly influences the luminosity and red (a*) and yellow chroma (b*) of central incisor(L*); the luminosity(L*), and yellow chroma(b*) of lateral incisor and canine (p<0.05). Smoking doesn't significantly influence the color of natural teeth. Drinking reduces the luminosity of central incisor as well as red chroma of lateral incisor(p<0.05). A chronic illness is likely to reduce the luminosity of central incisor and lateral incisor(p<0.05).

• Solar Energy
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• v.11 no.2
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• pp.3-8
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• 1991

This paper reports the application of the PSTAR(Primary and Secondary Terms Analysis and Henormalization) method to a thermally massive passive solar house located in Daejeon, Korea. The house has approximately $156m^2$ of living area with 3 bedrooms and a living room, which embodies many passive solar features for energy conservation. The primary concern of this work was to properly evaluate the thermal behavior of a thermally massive building structure using the PSTAR method. Results show close agreements between the measured and renormalized values in most cases in which the simulation results from the audit description of the house deviate somewhat considerably.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.04a
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• pp.164-164
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• 2013

화학 관련 산업은 고온, 고압뿐만 아니라 반응성이 큰 물질들을 사용하는 복잡한 공정으로 이에 맞는 안전기술이 요구된다. 산업 현장에서 취급하고 있는 각종 화학물질의 안전관리를 어렵게 하는 이유는 취급하는 물질의 화재 및 폭발 특성치에 관한 자료가 부족하거나 정확하지 않은 연소 특성치를 사용하기 때문이다. 가연성물질의 연소현상 가운데 하나인 자연발화는 가연성 혼합기체에 열 등의 형태로 에너지가 주어졌을 때 스스로 타기 시작하는 산화현상으로, 주위로부터 충분한 에너지를 받아서 스스로 점화할 수 있는 최저온도를 최소자연발화온도(AIT : Auto ignition Temperature)라고 한다. 최소자연발화온도는 가연성 액체의 안전한 취급을 위해 중요한 지표가 된다. 순수물질의 최소자연발화온도를 문헌들에서 비교하면, 동일 물질인데도 불구하고 문헌에 따라 다른 최소자연발화온도가 제시되고 있다. 따라서 사업장에서 사고를 예방하기 위해서는 정확한 연소 특성 자료를 이용해야 해야 한다. 그러나 문헌에 제시된 대부분의 자료들은 과거 표준장치 및 자체 제작된 장치 등을 사용해서 얻은 결과이므로, 최근에 고안된 표준 장치를 이용한 결과가 매우 유용한 자료가 될 것으로 본다. 본 연구에서는 자연발화온도를 측정하는데 있어서 최근에 고안된 표준장치인 ASTM E659장치를 이용하여 n-Propanol과 Formic acid 혼합물의 최소자연발화 온도를 측정하였다. n-Propanol과 Formic acid 혼합물의 최소자연발화 온도는 화학 관련 산업 공정에서 매우 중요한 자료가 될 것이다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.217-222
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• 2004

사진 측광은 일시에 대량의 데이터를 얻을 수 있으므로 시간에 따라 빛이 변화하는 주광의 측정 수단으로 이용될 수 있다. 이를 위하여 자연광 아래에서 디지털 이미지와 휘도 측정치의 보정실험을 행하였으나 청공광과 백색시료를 제외한 나머지 시료에 대해서는 그리 만족스러운 결과를 가져오지 못하였다. 앞으로 Videophotometry를 실현하기 위해서는 피 계측면의 분광 반사특성에 의한 계측치의 오차를 제거하기 위한 CCD 소자의 시감도 보정, 시야를 정확하게 재현하기 위한 광학적 연구, 인간의 시각 특성에 부합하는 측정 휘도의 보정 등에 대한 연구가 이루어져야 할 것이다.

• Journal of Periodontal and Implant Science
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• v.28 no.1
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• pp.1-16
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• 1998

자연치의 경우에는 치주지수간의 상관관계가 정립되어 병적인 상태에 대한 진단과 그에 따른 치료방법을 결정하는데 많은 정보를 제공하나, 인공매식치에서는 아직 논란의 여지가 많다. 이에 임상적으로 안정화되어 기능하고 있는 인공매식치에서 치주지수간의 상관관계에 관하여 연구하고자 하였다. 총 43명의 환자(평균 44.7세)에 식립된 178개의 인공매식치를 연구에 이용하였다. 인공치아매식술을 시행한 후 1년에서 6년이 경과한 인공매식치에서 상부보철물을 제거한 후 치태지수, 치은열구출혈지수, 각화점막지수, 치주낭깊이, Periotest Values(PTVs) 등을 측정하여 각각의 분포상황과 상관관계를 분석하였다. 이 연구의 결과는 다음과 같다. 1. 치태지수의 평균값은 $0.83{\pm}0.82$이었다. 2. 치은열구출혈지수의 평균값은 $1.04{\pm}0.86$이었다. 3. 각화점막지수의 평균값은 $2.47{\pm}0.95$이었다. 4. 치주낭깊이의 평균값은 $3.12{\pm}1.14\;mm$이었다. 5. Periotest Values(PTVs)의 평균값은 $-0.66{\pm}4.28$이었다. 6. 치태지수, 치주낭깊이가 증가함에 따라 치은열구출혈지수는 유의성있게 증가하였다(P<0.01). 7. 각화점막지수가 증가함에 따라 치은열구출혈지수는 유의성있게 감소하였다(P<0.01). 8. 치은열구출혈지수와 매식치동요도 사이에서는 유의성있는 상관관계를 발견할 수 없었다(P>0.05). 9. 치주낭깊이와 매식치동요도 사이에서도 유의성있는 상관관계를 발견할 수 없었다(P>0.05). 10. 인공매식치의 직경과 길이가 증가함에 따라 매식치동요도는 유의성있게 감소하였다(P<0.01). 11. 하악에서의 매식치동요도가 상악의 경우와 비교하여 유의성있게 작았다(P<0.01). 결론적으로, 인공매식치에서도 자연치에서와 동일한 양상으로 치태가 많을수록, 그리고 치주낭 깊이가 깊을수록 염증의 심도와 관련이 깊은 것으로 생각된다. 특히, 인공매식치의 경우에는 같은 양의 치태가 존재시에 각화치은이 충분히 있는 쪽이 염증발생이 적은 것으로 나타났다. 치주조직에 염증이 존재하는 경우, 자연치아에서는 치아의 동요도가 증가하는 것으로 알려져있으나, 이 실험의 인공매식치에서는 유의성있는 상관관계를 발견할 수 없었다. 임상적으로 안정화된 인공매식치의 동요도는 염증정도에는 큰 영향을 받지 않고 인공매식치의 직경과 길이가 증가함에 따라 감소함을 보여주고 있다. 또한, 인공매식치의 동요도는 상하악골의 골질에 따라 차이가 있음을 명확히 보여주고 있다.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.371-379
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• 2008

The aim of this study was to evaluate the tightness of proximal tooth contact(TPTC) using a novel device at rest state on implant prostheses. Ten healthy young adults with class I normal occlusion consented to participate in the study and twenty patients were restored with a total 20 single-implant crowns in the left maxillary and mandibular second molars for 10 single-implant crowns, respectively. Test area were divided by 4 groups. UM describes the contact between the upper natural left first molar and natural second molar; LM the contact between the lower natural left first molar and natural second molar; IUM the contact between the upper natural left first molar and implant second molar and ILM the contact between the lower natural left first molar and implant second molar. The TPTC was measured at rest state in each area. The mean TPTC of the UM, LM, IUM and ILM was 1.48(${\pm}0.44$) N, 1.78(${\pm}0.40$) N, 1.14(${\pm}0.37$) N and 1.30(${\pm}0.32$) N respectively. These results indicate that the TPTC was less between natural tooth and implant prosthesis than between natural teeth.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1292-1300
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• 1989

본 연구에서는 비원형관의 평판길이의 변화가 평판과 원관사이의 상호작용 으로 나타나는 온도장, 유동장, 국소 Nusselt 수 및 평균 Nusselt 수에 미치는 영향 에 대하여 고찰하였다.

• Korean Journal of Culture and Social Issue
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• v.22 no.3
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• pp.313-342
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• 2016

The purpose of the present study was to examine the relationship between individual values, nature-relatedness, and happiness in a sample of Korean university students(N=224). Specially, we used Schwartz's PVQ, life satisfaction, positive affect, psychological well-being, social well-being, and Korean Happiness scale to measure values and happiness. According to the bivariate correlational analysis, generally, there were positive correlation between benevolence, self-direction, universalism, stimulation and one of 5 happiness measurements and there was negative correlation between achievement and life satisfaction. Nature-relatedness were positively related with five types of happiness measurements. According to the hierarchical regression, demographic variables(sex, religion, economic levels), value types, and nature-relatedness explained 25%~36% of variance in happiness. Value was more related with psychological well-being than life satisfaction, positive affect, social well being, Korean happiness scale. This results emphasize the importance of healthy value(benevolence, self-direction) and provision of opportunities contact with nature to promote human happiness.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.202-210
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• 2014

Purpose: The aim of this study was to evaluate the stress concentration and distribution whether restoring the cavity or not while restoring with metal ceramic crown on tooth with abfraction lesion using finite element analysis. Materials and methods: Maxillary first premolar was selected and made a total of 10 finite element model. Model 1 was natural tooth; Model 2 was tooth with metal ceramic crown restoration which margin was positioned above 2 mm from CEJ; Model 3 was tooth with metal ceramic crown restoration which margin was positioned on CEJ; Model 4 was natural tooth which has abfraction lesion; Model 5 and 6 had abfraction lesion and the other condition was same as model 2 and 3, respectively; Model 7 was natural tooth which had abfraction lesion restored with composite resin; Model 8 and 9 was tooth with metal ceramic crown after restoring on abfraction lesion with composite resin; Model 10 was restored tooth on abfraction lesion with composite resin and metal ceramic crown restoration which margin is positioned on lower border of abfraction lesion. Load A and Load B was also designed. Von Mises value was evaluated on each point. Results: Under load A or load B, on tooth with abfraction lesion, stress was concentrated on the apex of lesion. Under load A or load B, on tooth that abfraction lesion was restored with composite resin, the stress value was reduced on the apex. Conclusion: In case of abfraction lesion was restored with composite resin, the stress was concentrated on the apical border of restored cavity regardless of marginal position. It was favorable to place crown margin on the enamel for restoring with metal ceramic crown.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.3
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• pp.318-327
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• 2019

The purpose of this study was to identify which combination of zirconia crowns and cements is most similar in color to the maxillary primary incisors by varying the color of zirconia crowns, crown thickness, and shade of cements. Prefabricated zirconia crowns in 3 shades and crowns fabricated using 6 types of zirconia blocks were used in this study. These were filled with A2-shade or translucent-shade resin cement and the $L^*$, $a^*$, and $b^*$ values were calculated using a spectrophotometer. The color differences between the natural teeth and the zirconia crowns were assessed. The shade of the final restoration was more similar to that of the natural teeth using A2-shade than translucent-shade resin cement. Application of A2-shade cement to a 0.5-mm-thick crown fabricated from a smile series 2 zirconia block resulted in the color most similar to that of the natural teeth. A2-shade resin cement is recommended for zirconia crown restoration in anterior primary teeth compared to TR-shade resin cement for more esthetic restoration. Since restorations with Nu-smile zirconia crowns were not esthetically favorable in terms of shade, improvement of the shade characteristics of the product or development of a new kind of zirconia crown is required.