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- 저자 : 황소라(So Ra Hwang) (검색결과 4 건)
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황소라 ( So Ra Hwang ) 대한예방치과·구강보건학회 2019 大韓口腔保健學會誌 Vol.43 No.2
Objectives: The objectives of this study were to determine the radiation safety status of dental care institutions and to contribute to the development of guidelines for radiation protection in dental clinics in order to improve the work environment and reduce the radiation hazard for practitioners. Methods: The subjects were selected using a convenience sampling. A total of 300 subjects partici pated in this study, including 150 dental hygienists from dental clinics in Gwangju Metropolitan City with radiation-related work experience and 150 dental hygienists who had participated in a seminar hosted by the Korean Dental Insurance Manager Association held on January 17, 2016. For the survey, self-en try questionnaires were used, and the collected data were analyzed by performing a frequency analysis using cross tabulation (c2-test) and t-test, one-way analysis of variance, and multiple regression analysis. Results: The awareness on radiation protection among dental hygienists showed 4.4 out of 5 points, which was high, but the practice of radiation protection was overall poor. For the necessity of develop ing radiation protection guidelines, 91.9% answered “Yes, it is necessary.”. Conclusions: The level of radiation protection practiced at dental healthcare centers was much lower than the awareness of it and showed that the requirement of guidelines for radiation protection was high. Therefore, institutional devices require the development and utilization of various types of radiation protection guidelines in order to mitigate radiation risks and improve the work environment.
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황소라(So Ra Hwang),최창형(Chang Hyung Choi),김휘찬(Hui Chan Kim),김인호(In Ho Kim),이창수(Chang Soo Lee) 한국고분자학회 2012 폴리머 Vol.36 No.2
본 연구에서는 poly(dimethylsiloxane)(PDMS) 기반의 미세유체 시스템을 이용하여 이중 에멀젼을 형성하는 방법을 구현하였다. 반응기 친수성 연속상과 표면 젖음성을 향상시키기 위해 우선 PDMS 표면과 3-(trimethoxysilyl) propyl methacrylate(TPM)간의 졸-젤 반응을 통해 표면에 메타크릴레이트를 유도하였고, 선택적인 영역에 친수성 단량체인 아크릴산과 메타크릴레이트간의 공유결합을 유도하였다. 이를 확인하기 위해 아크릴산과 정전기적 인력 결합을 하는 염료를 통하여 선택적 표면 개질의 성공을 확인하였다. 사용된 유체로는 "spreading coefficient"를 도입 하여 시스템 내에서 이중 에멀젼을 형성하는 조건을 예측하여 물과 0.5% w/w sodium dodecyl sulfate 혼합물, 헥사 데칸 혼합물(hexadecane; 1% w/w Span80)을 선정하였다. 이를 통하여, 코어 및 쉘의 사이즈가 48.5 μm(CV:1.6%), 65.1 μm(CV:1.6%)인 단분산성 이중 에멀젼을 성공적으로 생성하였고, 유체의 유량 제어를 통하여 함입되는 코어 의 개수 조절이 가능함을 보여주었다. This study presents the preparation of double emulsions in a poly(dimethylsiloxane) (PDMS)-based microfluidic device. To improve the wettability of hydrophilic continuous phase onto a hydrophobic PDMS microchannel, the surface was modified with 3-(trimethoxysilyl) propyl methacrylate (TPM) and then sequentially reacted with acrylic acid monomer solution, which produced selective covalent bonding between acrylic acids and methacrylate groups. For the proof of selective surface modification, tolonium chloride solution was used to identify the modified region and we confirmed that the approach was successfully performed. When water containing 0.5% w/ w sodium dodecyl sulfate and 1% w/w Span80 with hexadecane were loaded into the selectively modified microfluidic channels, we can produce stable double emulsion. Based on the spreading coefficients, we predict the morphology of double emulsions. Our proposed method efficiently produces monodisperse double emulsions having 48.5 μm (CV:1.6%) core and 65.1 μm (CV:1.6%) shell. Furthermore, the multiple emulsions having different numbers of core were easily prepared by simple control of flow rates.
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황소라 ( So-ra Hwang ),김지은 ( Ji-eun Kim ),정기호 ( Ki-ho Chung ),최충호 ( Choong-ho Choi ) 대한예방치과·구강보건학회 2019 大韓口腔保健學會誌 Vol.43 No.4
Objectives: We investigated the effects of commercial plum beverage on the dentin surface that could be exposed to caries, gliopathy, and abrasion to investigate the inhibitory effects of dentin corrosion. Methods: The experimental beverages were Jeju Samdasoo (Group 1, negative control), Coca-Cola (Group 2, positive control), Chorok Maesil (Group 3), and Chorok Maesil with 3% calcium lactate added (Group 4). The specimens were prepared and divided into 4 groups of 12 each. The pH of the experimental beverages was measured using a pH meter, and specimen surface hardness was assessed according to the Vickers hardness number (VHN). The specimens were immersed in the experimental beverage for 1, 3, 5, 10, and 15 minutes. Then, we obtained the average VHN by measuring surface microhardness. Measures of surface microhardness were compared using the paired t-test before and after 15 minutes of immersion in each of the four beverages. Between-group differences in surface microhardness were compared using one-way analysis of variance and the Tukey test after the analysis. Results: After 15 minutes of immersion in the experimental beverages, there was no significant difference in surface microhardness in group 1 (P>0.05). There were significant differences in groups 2, 3, and 4 (P<0.05). The difference in surface microhardness before and after immersion for 15 minutes was highest in group 3 (―18.1±2.55), followed by group 2 (―13.0±3.53) and group 4 (―7.79±4.47). In group 1, the difference was ―1.52±4.30. Moreover, there was a significant difference in each group (P<0.05). After 10 minutes of immersion, surface microhardness tended to rapidly decrease. Conclusions: Patients who regularly ingest a commercially available plum drink with low pH should be provided dietary guidance on the risk of dental erosion. Calcium additives should be considered when producing plum beverage products.
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미세채널에서 수력학적 조절을 통한 단분산성 다중 액적 생성
강성민 ( Sung Min Kang ),최창현 ( Chang Hyung Choi ),황소라 ( So Ra Hwang ),정재민 ( Jae Min Jung ),이창수 ( Chang Soo Lee ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.4
This study reports the microfluidic preparation of monodisperse multiple emulsions using hydrodynamic control. To generate multiple emulsions, we fabricate a microfluidic capillary device based on co-flowing stream without any surface modification of microchannels. Based on the system, we can successfully generate multiple emulsions (W/O/W) using water containing 0.5 wt% Tween 20, n-hexadecane with 5 wt% Span 80, and 10 wt% poly (vinyl alcohol) (PVA) aqueous solution, respectively. Furthermore, we control the number of inner droplets by modulation of flow rate of inner fluid at fixed flow rate of middle and outer fluid. The multiple emulsions having precisely controlled inner droplets` size and number can be applicable for multiple chemical reactions as an isolated microreactor.
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