• 한국치위생학회지
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• 제4권1호
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• pp.65-79
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• 2004

There are two purposes in this study. The first one is to collect some oral health information through the investigations upon the oral health care of Korean adults. Referring to the result of the investigation. I wanted to furnish fundamental data with oral health education for each age and with a publicity booklet editing. That is the second purpose of this research. Among the people who visited Seo-gu Public Health Center in Kwang-ju, 207 people answered the questionnaires. There were 86 men and 121 women from the 20-aged to the 59- aged. The questionnaires covers knowledge aquisition path for dental caries prevention, the cognition degrees for the causes of dental caries and its prevention, the cognition degrees for the causes of periodontal disease and its prevention, the degrees for oral health methods, and the importance of oral health. The conclusions are as follows; 1. The cognition degree for dental caries prevention: The cognition for pit and fissure sealant was appeared most highly in thirties by 85.3%. but 62.1 % in fifties was answered, "Never heard". The cognition degree for fluoride application was appeared most highly in thirties by 73.5%. and the cognition degree for water fluoridation was most highly in forties by 54.2%. 2. The knowledge for pit and fissure sealant was acquired mostly through dental hospital in every age by 54.2%. 3. The knowledge for fluoride application was learned mostly through dental hospitals in twenties and thirties by 32.7%. and mostly through TV or radio health programs in forties and fiftieseach by 35.7% and 50.0%. 4. The knowledge for water fluoridation was acquired through TV or radio programs in all ages such as twenties. thirties. forties and fifties. Its rate was 57.8%. 5. The cognition degree of the cause of dental caries: 53.1 % of all ages think that dental caries can most frequently be caused by being lack of toothbrushing. 6. The cognition degree of the cause of periodontal disease: 58.5% people of all ages think that both dental plaque and calculus might be the main cause of periodontal disease. 7. The cognition degree of dental caries prevention: 72.8% people think that dental caries can be prevented by right tooth brushing method. and 8.7% people think that they can be prevented by scaling. However, 10.7% people of them were not interested in dental caries prevention. 8. The importance of oral health: 35.3% people think that teeth health is the most important, and 63.8% people think oral health is one of the most important health problems. Forties answered that tooth health was the most important thing, and fifties. thirties and twenties followed in the order. 9. The cognition for oral health maintenance: all ages(twenties. thirties. forties. and fifties) answered that right toothbrushing method was the best way to keep oral health by 69.1%.

• Restorative Dentistry and Endodontics
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• 제35권5호
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• pp.313-320
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• 2010

연구목적: 본 연구의 목적은 미세 유체 흐름 측정장치를 이용해서 각 상아질 지각과민 처치제의 적용 과정 중 발생하는 상아 세관액 흐름의 유동을 관찰하고, 상아질 지각과민 처치제 간 적용 후 투과도 감소의 차이를 비교하고자 하는 것이다. 연구 재료 및 방법: CEJ 5 mm 하방에서 절단한 소구치를 미세 흐름 측정장치에 연결하여 20 cm $H_2O$의 정수압을 가하였다. 치경부에 상하 3 mm, 근원심 4 mm, 깊이 2 mm의 V자 형태의 5급 와동을 형성하고 smear layer를 제거하기 위해 15초 동안 산 부식한 후 상아질 지각과민 처치제를 적용하였다. 사용된 상아질 지각과민 처치제는 Seal&Protect (SP), SuperSeal (SS), BisBlock (BB), Gluma desensitizer (GL), Bifluoride 12 (BF) 이다. 상아세관액의 흐름은 지각과민 처치제 도포 전부터 도포 후 5분까지 실시간으로 측정되었다. 결과: 실험에 사용한 모든 상아질 지각과민 처치제는 적용 후의 상아세관액 흐름율이 적용 전에 비해 유의하게 감소하였다(p < 0.05). SP는 GL과 BF에 비해 유의하게 투과도 감소가 나타났다 (p < 0.05). SS와 BB는 BF에 비해 유의하게 투과도 감소를 보였다 (p < 0.05). 결론: 지각과민 처치제의 도포 과정 동안 각 처치제의 특징적인 상아세관액의 유동을 미세 유체 흐름 측정장치를 통해 관찰 할 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.423.1-423.1
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• 2016

Polyvinylidene fluoride (PVDF) has drawn much attention due to its many advantages. PVDF shows high mechanical strength and flexibility, thermal stability, and good piezoelectricity enabling its application to various fields such as sensors, actuators, and energy transducers. Further studies have been conducted on PVDF in the form of thin films. The thin films exhibit different ionic conductivity according to the number of pores within the film, letting these films to be applied as electrolytes or separators of batteries. Porous PVDF membranes are also easily processed, usually made by using electrospinning. However, a large portion of researches were conducted using PVDF membranes produced by far field electrospinning, which is not a well-controlled experimental method. In this paper, we use near field electrospinning (NFES) process for more controlled, small-scaled, mesh type PVDF structures of nano to micro fibers fabricated by controlling process parameters and investigate the properties of such membranous structures. These membranes vary according to geometrical shape, pore density, and fiber thickness. We then measured the mechanical strength and piezoelectric characteristic of the structures. With various geometries in the fiber structures and various scales in the fibers, these types of structures can potentially lead to broader applications for stretchable electronics and dielectric electro active polymers.

• 소음진동
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• 제5권3호
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• pp.313-325
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• 1995

Two active/passive vibration dampers were designed to control a cantilever beam first mode of vibration. The active element was a piezoelectric polymer, polyvinlidene fluoride (PVDF). The passive damping was provided by the application of a viscoelastic layer on the surface of the steel beam. Two substantially different damper configurations were designed and tested. One damper consisted of a piezoelectric actuator bonded to one face of the beam, with a viscoelastic layer applied to the other surface of the beam. The second one was composed of a layer viscoeastic layer with one surface bonded to the beam, and with other being constrained by nine piezoelectric actuators connected in parallel. A control law based on the sign of the angular velocity of the cantilever beam was implemented to control the beam first mode of vibration. The piezoelectric sensor output was digitally differentiated to obtain the transverse linear velocity, and its sign was used in the control algorith. Two dampers provided the system a damping increase of a factor of four for the first damper and three for the second damper. Both dampers were found to work well at low levels of vibration, suggesting that they can be used effectively to prevent resonant vibrations in flexible structure from initiating and building up.

• Membrane and Water Treatment
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• 제5권2호
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• pp.109-122
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• 2014

Polyvinylidene fluoride (PVDF) hollow fiber membrane is widely used for water treatment. However, the weak mechanical strength of PVDF limits its application. To enhance its tensile strength, a double-layer composite hollow fiber membrane, with PVDF and polyetherimide as the external and inner layers, respectively, was successfully prepared through phase inversion technique. The effects of additive content, air gap distance, N,N-dimethyl-acetamide content in the inner core liquid, and the temperature of external coagulation bath on the membrane structure, permeation flux, rejection, tensile strength, and porosity were determined. Experimental results showed that the optimum preparation conditions for the double-layer composite hollow fiber membrane were as follows: PEG-400 and PEG-600, 5 wt%; air gap distance, 10 cm; inner core liquid and the external coagulation bath should be water; and temperature of the external coagulation bath, 40 C. A single layer PVDF hollow fiber membrane (without PEI layer) was also prepared under optimum conditions. The double-layer composite membrane remarkably improved the tensile strength compared with the single-layer PVDF hollow fiber membrane. The permeation flux, rejection, and porosity were also slightly enhanced. High-tensile strength hollow fiber PVDF ultrafiltration membrane can be fabricated using the proposed technique.

• 멤브레인
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• 제27권4호
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• pp.350-357
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• 2017

본 연구는 열유도 상분리법(thermally induced phase separation, TIPS)을 사용하여, 수처리 분리막에 적용하기 위해, 응고조의 온도 및 열용량의 변화에 따른 분리막의 모폴로지 변화를 관찰하였다. 분리막을 제조하기 위한 소재로는 기계적 물성과 내화학성이 우수한 poly(vinylidene fluoride)(PVDF)와 실리카를 이용하였고, 희석제로는 dioctyl phthalate (DOP), dibutyl phthalate (DBP)를 사용하였다. 다양한 응고액의 열용량 변화에 따른 구조 변화 관찰을 위하여 SEM 이미지를 관찰하였다. 열용량이 증가할수록 PVDF의 결정화 속도가 느려져 큰 기공을 나타내며 열용량이 작을수록 결정화 속도가 증가하여 작은 기공이 생기는 것을 확인하였다.

• Preventive Nutrition and Food Science
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• 제19권3호
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• pp.213-219
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• 2014

Bacillus pumilus 2.g isolated from gembus, an Indonesian fermented soybean cake, secretes several proteases that have strong fibrinolytic activities. A fibrinolytic enzyme with an apparent molecular weight of 20 kDa was purified from the culture supernatant of B. pumilus 2.g by sequential application of ammonium sulfate precipitation, ion-exchange chromatography, and hydrophobic chromatography. The partially purified enzyme was stable between pH 5 and pH 9 and temperature of less than $60^{\circ}C$. Fibrinolytic activity was increased by 5 mM $MgCl_2$ and 5 mM $CaCl_2$ but inhibited by 1 mM phenylmethylsulfonyl fluoride (PMSF), 1 mM sodium dodecyl sulfate (SDS), and 1 mM ethylenediaminetetraacetic acid (EDTA). The partially purified enzyme quickly degraded the ${\alpha}$ and ${\beta}$ chains of fibrinogen but was unable to degrade the ${\gamma}$ chain.

• International Journal of Oral Biology
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• 제43권2호
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• pp.83-91
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• 2018

Nonthermal atmospheric plasma has been studied for its many biomedical effects, such as tooth bleaching, wound healing, and coagulation. In this study, the effects of dentinal tubules occlusion were investigated using fluoride-carboxymethyl cellulose (F-CMC) gel, nano-sized hydroxyapatite (n-HA), and nonthermal atmospheric plasma. Human dentin specimens were divided to 5 groups (group C, HA, HAF, HAP, and HAFP). Group HA was treated with n-HA, group HAF was treated with n-HA after a F-CMC gel application, group HAP was treated with n-HA after a plasma treatment and group HAFP was treated with n-HA after a plasma and F-CMC gel treatment. The occlusion of dentinal tubules was investigated using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS), which shows Ca/P ratio. In the EDS results, a higher Ca/P ratio was shown in the groups including n-HA than in the control group. The specimens of group HAP and HAFP had a higher Ca/P ratio in retentivity. In the SEM results, there was not a significant difference in the amount of times applied. Therefore, this study suggests F-CMC gel and n-HA treatment using nonthermal atmospheric plasma will be a new treatment method for decreasing hypersensitivity.

• 한국치위생학회지
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• 제11권5호
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• pp.749-758
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• 2011

Objectives : The purpose of this study was to analyse case reports performed through a dental hygiene process and provide basic data on clinical education of dental hygiene. Methods : 154 case reports which collected for six years were analysed. This study applied dental hygiene process model in dental hygiene diagnosis. Dental hygiene diagnosis was more cleared by dental a hygiene process model. Data analysis was performed by the Frequency statistics using SPSS 12.0 for Windows. Results : 1. The clients are mainly comprised 20's university student(91.9%). 2. In assessment phase, clients finished 100% test of subjective data. 3. When applied a dental hygiene process model in dental hygiene diagnosis, students have identified 23 type of dental hygiene problem and analysed dental hygiene problem frequently used as bleeding of gingiva, calculus and deposit of dental plaque. 4. In case of plan of dental hygiene intervention, Fluoride application showed the most high level(98.1%) in clinical intervention. 5. Results of intervention showed that performance rate(98.7%) of scaling is the most high level. Conclusions : Dental hygiene process model is more useful than other diagnostic models in clinical practice based on dental hygiene process.

• 한국치위생학회지
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• 제15권6호
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• pp.999-1007
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• 2015

Objectives: The objective of the study is to investigate oral health behavior and oral health education experience in Korean adolescents from the ninth(2013) web-based survey of Korean youth risk behavior. Methods: The subjects were 72,435 students through the ninth 2013 web-based survey of Korean youth risk behavior conducted by the Ministry of Education, Science, and Technology, the Ministry of Health and Welfare, and the Korea Centers for Disease Control. The questionnaire consisted of socio-demographical characteristics of the subjects, oral health behavior, and oral health education experience. Data were analyzed by SPSS 18.0 program. Results: Oral health education had much influence on tooth brushing after lunch, oral cavity disease prevention, sealants, fluoride application, scaling experience, and consumption of vegetables, milk, carbonated soft drinks, noodles, and snacks. The oral health education had a great impact on those who took good oral health behavior into action. Conclusions: It is very important and necessary to develop the continuing effective oral health education program for the adolescents and make them tale into action.