Machined 티타늄 임플란트와 calcium phosphate coated 티타늄 임플란트의 조직형태계측학적 연구

강현주,양재호,Kang, Hyun-Joo,Yang, Jae-Ho 대한치과보철학회 2010 대한치과보철학회지 Vol.48 No.2

연구목적: 본 연구는 machined 임플란트와 골유도능이 있는 calcium phosphate를 electron-beam deposition으로 coating처리한 임플란트의 골/임플란트 접촉률을 조직형태계측학적으로 비교하는 것이다. 연구 재료 및 방법:여섯 마리의 수컷 New Zealand white rabbit과직경3.3 mm, 길이 5 mm의 임플란트 24개를 준비하였다. Machined 임플란트 (대조군)와 calcium phosphate coated 임플란트(실험군)를 좌, 우 경골에 2개씩 총 4개를 식립하고 임플란트 주위에 부하가 가해지지 않도록 하여 3주, 6주의 치유기간을 두었다. 식립 3주와 6주후, 각각 3마리의 토끼를 희생하여 조직시편을 제작하였다. 제작된 시편을 광학현미경 하에서 골/임플란트 접촉률 (BIC ratio)을 계산하고 paired t-test로 두 군을 비교하였다. 결과:골/임플란트 접촉률은 임플란트 식립 3주후, 대조군에서 평균과 표준편차는$44.1{\pm}16.5%$ 이었고 실험군은 $70.8{\pm}18.9%$로 실험군이 통계적으로 유의하게 높았다 (P= 0.0264). 6주후의경우, machined 임플란트는 $78.6{\pm}15.1%$, calcium phosphate coated 임플란트는 $79.0{\pm}26.0%$로 두 군 간 통계적으로 유의한 차이는 없었다. 결론: Calcium phosphate coated 임플란트는 machined 티타늄 임플란트에 비해 빠른 초기 골반응을 나타냈다. 그러므로, 임상적으로 calcium phosphate coated 임플란트를 사용했을 때, 수술 후 치유 기간을 단축하여 조기 부하가 가능할 것으로 사료된다. Purpose: The objective of this study was to investigate the effects of calcium phosphate coated titanium implant surface on bone response and implant stability at early stage of healing period of 3 weeks and later healing period of 6 weeks. Material and methods: A total of 24 machined, screw-shaped implants (Dentium Co., Ltd., Seoul, Korea) which dimensions were 3.3 mm in diameter and 5.0 mm in length, were used in this research. All implants (n = 24), made of commercially pure (grade IV) titanium, were divided into 2 groups. Twelve implants (n = 12) were machined without any surface modification (control). The test implants (n = 12) were anodized and coated with thin film (150nm) of calcium phosphate by electron-beam deposition. The implants were placed on the proximal surface of the rabbit tibiae. The bone to implant contact (BIC) ratios was evaluated after 3 and 6 weeks of implant insertion. Results: The BIC percentage of calcium phosphate coated implants ($70.8{\pm}18.9%$) was significantly higher than that of machined implants ($44.1{\pm}16.5%$) 3 weeks after implant insertion (P = 0.0264). However, there was no significant difference between the groups after 6 weeks of healing (P > .05). Conclusion: The histomorphometric evaluation of implant surface revealed that; 1. After 3 weeks early healing period, bone to implant contact (BIC) percentage of calcium phosphate coated implants (70.8%) was much greater than that of surface untreated machined implants (44.1%) with P = 0.0264. 2. After 6 weeks healing period, however, BIC percentage of calcium phosphate coated implants group (79.0%) was similar to the machined only implant group (78.6%). There was no statistical difference between two groups (P = 0.8074). 3. We found the significant deference between the control group and experimental group during the early healing period of 3 weeks. But no statistical difference was found between two groups during the later of 6 weeks.

이동통신망을 이용한 지리 기반 재난경보서비스의 국가별 동향 분석

강현주,주상임,오승희,정우석,H.J. Kang,S.L. Ju,S.H. Oh,W.S. Jung 한국전자통신연구원 2023 전자통신동향분석 Vol.38 No.3

Governments intend to use the public warning system to deliver timely and accurate information using accessible communication technologies for protecting the population and reducing damage to life and property. In particular, many countries implement system interworking with smartphones to notify of disasters or emergencies. In Korea, since 2020, due to the influence of the coronavirus disease, frequent emergency text messages led people to turn off related notifications, and complaints for receiving irrelevant messages from nearby warning areas have increased. Therefore, technical improvements for issuing more accurate disaster information to a specific region should be devised through a geography-based emergency disaster message transmission service. We analyze development trends of public warning systems and service cases of geography-based emergency text transmission services in various countries.

내구성 향상을 위하여 단열성능이 부여된 단면복구 MORTAR의 물성

강현주,나승현,송명신,정의담,서병돌,Kang, Hyun-Ju,Na, Seung-Hyun,Song, Myong-Shin,Jeong, Eui-Dam,Seo, Byung-Dol 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.5

In this study, we studied on the durability of restorative cement mortar for deteriorated concrete at complex deteriorated conditions as variation of temperature and of humidities. We made a comparison between restorative materials with insulation function and restorative materials without insulation function in items of compressive and bending strength and permeability of water, durability for carbonation, salt damage, diffusion coefficient of salt at complex deterioration conditions like change of temperature, change of humidity, For insulation, we used close-pore type Alumino-Silicate lightweight aggregate and substituted 12 wt% and 15 wt% out of original restorative cement mortar without insulation function. As a result, it was found that original restorative cement mortar without insulation function fail to meet Korean Standard on polymer modified cement mortar for maintenance in concrete structure, but restorative cement mortar with insulation function is in contentment Korean Standard to meet excellent than restorative materials without insulation function for durability at complex deteriorated conditions.

보건계열 대학생들의 스트레스와 정서조절에 따른 대학생활적응 관련성 연구

강현주,Kang, Hyun-Joo 한국융합학회 2021 한국융합학회논문지 Vol.12 No.9

본 연구는 보건계열 대학생의 스트레스와 정서조절, 대학생활적응에 영향을 미치는 요인을 연구하기 위함이다. G광역시, J지역 보건계열학과 190명을 연구 대상으로 2021년 6월 21일부터 30일까지 설문조사를 하였다. 자료의 분석은 빈도분석, 신뢰도분석, 단순상관분석, 다중회귀분석을 사용하였다. 결과는 긍정적 지각은 부정적 지각(r=-.286, p<.01), 정서조절(r=.296, p<.01), 대학생활적응(r=.520, p<.01)과 정(+)의 상관이 있었다. 부정적 지각은 정서조절(r=-.619, p<.01), 대학생활적응(r=-.428, p<.01)과 부(-)의 상관이 있었다. 정서조절은 대학생활적응(r=.341, p<.01)과 정(+)의 상관이 있었다. 지각된 스트레스 하위요인인 긍정적 지각, 부정적 지각, 정서조절이 대학생활 적응에 영향을 미치는 요인이었으며 설명력은 84%이었다. 그러므로 보건계열 대학생의 대학생활 적응을 향상시킬 수 있는 프로그램 개발이 필요할 것으로 생각된다. The purpose of this study is to investigate the factors that affect stress, emotional regulation, and adjustment to college life of health college students. The survey was conducted from June 21 to 30, 2021 for 190 health students in G and J area. The data were analyzed by frequency analysis, reliability analysis, simple correlation analysis, and multiple regression analysis. The results showed that positive perception had positive correlation with negative perception(r=-.286,p<.01), emotional regulation (r=.296,p<.01), and university life adjustment(r=.520,p<.01). Negative perception was correlated with emotional regulation(r=-.619,p<.01), university life adjustment (r=-.428,p<.01) and negative(-). Emotional regulation had a positive correlation with university life adjustment(r=.341,p<.01). Positive perception, negative perception, and emotional regulation, which are sub-factors of perceived stress, were the factors affecting the adjustment to university life, and the explanatory power was 84%. Therefore, it is necessary to develop a program that can improve the adjustment of college students in health.

수중불분리콘크리트에 사용되는 멜라민유동화제 개발

강현주,이경희,조인성,박의순,Kang, Hyun-Ju,Lee, Kyung-Hee,Cho, In-Sung,Park, Soon-Eui 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.10

본 연구에서는 수중불분리혼화제로서 메칠셀룰로스계를 사용하였고 자체 개발한 멜라민유동화제의 수중불분리콘크리트에 대한 사용량을 5, 7, 9, 11 kg/$m^3$으로 첨가량을 달리하여 slump folw, flow loss, 응결사간, 탁도 및 pH, 압축강도, 수중/기중 압축강도비를 실험한 결과 수중불분리콘크리트의 물성이나 경제성등을 고려할 때 수중불분리콘크리트에서의 멜라민유동화제의 사용량은 약 9 kg/$m^3$인 것으로 나타났다. In this studies, methly celluloes was used as antiwashout admixture and when considering the physical properties and economical efficiencies of Underwater Concrete as the results of making an experiencing slump flow, flow loss, setting time, suspension and pH also compressive strength and underwater/an air compressive strength ratio according to the adding amount changes 5, 7, 9, 11 kg/$m^3$ to Underwater Concrete of melamine superplasticizer, the using amount of melamine superplasticizer in Underwater Concrete approximately represents 9 kg/$m^3$.

콘크리트 내구성 향상을 위한 시멘트 재료의 수밀성 개선에 관한 연구

강현주,송명신,정의담,Kang. Hyun-Ju,Song. Myong-Shin,Jeong. Eui-Dam 한국방재학회 2010 한국방재학회논문집 Vol.10 No.5

콘크리트의 내구성능 향상을 위한 방안으로서 시멘트 재료의 수밀성능 증진에 대한 연구를 수행하였다. 보통 포틀랜드 시멘트 및 보통 포틀랜드 시멘트와 플라이애쉬의 혼합계 재료에 다양한 성능의 수밀성능 개선제를 혼합하여 수밀성 실험을 진행한 결과, 시멘트 재료의 수밀성능 향상은 시멘트 수화생성물인 CSH의 생성과 유기지방산에 의한 수화물과의 접촉각의 크기와 밀접한 관계가 있으며 수화초기에 활발하게 생성되는 CSH는 수밀성과 장기적인 흡수율 저감에 영향을 주는 것으로 나타났다. 또한 시멘트 재료의 작업성 개선을 위하여 플라이애쉬를 사용하는 경우, 구형 플라이애쉬의 작업성 증진에 의해 시멘트 재료의 조직이 치밀화 되고 포졸란 재료의 특성에 의한 CSH의 생성으로도 수밀성이 향상 되는 것으로 나타났다. 다양한 종류의 수밀성 재료를 혼합하여 흡수율 및 수화 생성물의 변화에 대해 실험한 결과, 콘크리트의 내구성 향상을 위해서는 어떠한 형태이든 시멘트 재료에 수밀성 혼화제의 혼합 사용이 바람직 한 것으로 판단된다. We studied on the watertightness improvement of cementitious material for durability enhancement of concrete. For improvement of watertightness of OPC and OPC with fly ash, we used various materials with watertightness properties to OPC and OPC with fly ash. The performance of watertightness improvement of cementitious materials closely related to formation of CSH by pozzolanic reaction and to reducing of size of contact angle in cement pore by using organic fatty acid. And volume of CSH formation at early hydration have an influence of watertightness improvement and reduction of long-term water absorption rate. In using of fly ash, improvement of workability by using the spherical fly ash caused to densify on the structures of cement material and CSH formation by pozzolanic reaction and cement using fly ash also caused watertightness improvement of cementitious materials. For improvement of concrete durability by watertightness, cementitious materials need using watertightness materials and at using fly ash, also it have to the effect of improvement of watertightness of cementitious materials by pozzolanic reaction.

pH 변화에 따른 고로수쇄 BFS의 초기 수화 특성

강현주,이웅걸,송명신,강승민,김경남,Kang, Hyun Ju,Lee, Woong Geol,Song, Myong Shin,Kang, Seung Min,Kim, Kyeng Nam 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.5

This study investigated on the early hydration and physical characteristics of BFS by pH variation. NaOH solution was used as a pH activator. In the range from pH 12 to pH 14, Experiment was compared the hydration propertied of OPC(Ordinary Portland Cement) and BFS(Blast Furnace BFS) and BFS containing 2 wt% of gypsum. It was found that CAH(Calcium Aluminate Hydrates) phases and CSH(Calcium Silicate Hydrates) phases were formed during the early hydration of BFS, and that CAH phases, CSH phases and ettringites were formed during the early hydration of BFS containing 2 wt% of gypsum. Furthermore, early hydration of BFS and BFS containing 2 wt% of gypsum were faster then OPC at pH 14, and the 1 day compressive strength of BFS increased by approximately 30% compared to OPC, and BFS containing 2 wt% of gypsum also increased by approximately 40% compared to OPC.

시멘트의 수화특성에 대한 유·무기 복합 나노실리카의 영향

강현주,송명신,박종헌,송수재,Kang, Hyun-Ju,Song, Myong-Shin,Park, Jong-Hun,Song, Su-Jae 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.6

In this study, as a material used to replace silica fumes for high strength concrete, nano-silica compound with organic functional group for dispersion and with inorganic silica group that can cause a pozzolan reaction is synthesized, These nano silica compound is divided into IC, which is nano size $SiO_2$ with irregularly combined hydroxyl group and carboxyl group, and RC, which is nano size $SiO_2$ with regularly combined hydroxyl group and carboxyl group. The effects of these nano silica compound on the hydration of cement are reviewed. As a result, all of synthesized nano-silica compounds have excellent dispersion on the cement flow, we think that dispersion property is the effect of air entraining by synthesized nano-silica compounds. The result of the microstructure observation showed that the particle size of the synthesized nano-silica is smaller than silica fume and spread evenly among the cement particles. In initial The phenomenon of strength decreasing occurred due to delayed hydration reaction by the synthesized nano-silica with carboxyl(-COOH) and hydroxyl(-OH) functional group.

구체방수제가 혼입된 시멘트 경화체의 방수 메카니즘

강현주,송명신,박종헌,전세훈,이성현,Kang, Hyun Ju,Song, Myong Shin,Park, Jong Hun,Jeon, Se Hoon,Lee, Sung Hyun 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.1

The pore volume of hardened cement with waterproofing materials is lower compared to that of hardened cement without waterproofing materials. Thus, fewer gaps will appear by means of chemical reactions between $Ca^{2+}$ ions in hardened cement and water, solutes, and other ions. Due to the selective permeability, the osmotic pressure of hardened cement can change due to physical effects such as the reduction of the pore volume and the reduction in the number of pores, as well as by the electrochemical reaction between water, solutes, other ions and $Ca^{2+}$ ions in hardened cement. Of course, these factors do not have independent effects but instead a combined complex effect. Accordingly, we studied changes in the osmotic pressure due to the difference in the pore structure of hardened cement. A pore size smaller than 1 nm in hardened cement had only a slight effect on the osmotic pressure, whereas a pore size larger than 1 nm had a direct effect on the osmotic pressure.

고성능 감수제 종류에 따른 실리카흄이 혼입된 시멘트 수화 특성

강현주,송명신,박종헌,송수재,Kang, Hyun-Ju,Song, Myong-Shin,Park, Jong-Hun,Song, Su-Jae 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.6

In this study, the effect of superplasticizers on the dispersibility and hydration properties of cement with silica fume were investigated. Superplasticizers are used Naphthalene type, Ligno-sulfate type and polycarboxylate type. Compared with plastic viscosity of cement paste without superplasticizers(Plain), plastic viscosity of cement paste with superplasticizers are reduced and yield stress of cement pastes with each superplasticizer is increased rather than Plain. And then, plastic viscosity of cement paste with Naphthalene type superplasticizer was the least of all types. Compared with other two types, setting and hydration of cement paste with Polycarboxylate type(PC) superplasticizer is very fast. At compressive strength after 3-day, PC is higher than other two types, But, compressive strength of after 7-day and 28-day, PC is smaller than other two types.