• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 하계학술대회 논문집
• /
• pp.127-130
• /
• 2002

In this study, development of a new LTCC material using a non-glassy system was attempted with respect to reducing the fabrication process steps and cost down. Lowering the sintering temperature can be achieved by liquid phase sintering. For LTCC application, the starting material must have quality factor as high as possible in microwave frequency range. And also, the material should have a low dielectric constant for enhancing the signal propagation speed. Regarding these factors, dielectric constants of various materials were estimated by the Clausius-Mosotti equation. Among them, CaWO$_4$ was tamed out the suitable LTCC material. CaWO$_4$ can be sintered up to 98% of full density at 1200$^{\circ}C$ for 3 hours. It's measured dielectric constant, quality factor, and temperature coefficient of resonant frequency were 10.15, 62880GHz, and -27.8ppm/$^{\circ}C$, respectively. In order to modify the dielectric properties and densification temperature, 0.5∼1.5 wt% LiF were added to CaWO$_4$. LiF addition reduced the sintering temperature/time down to 800$^{\circ}C$/10∼30min due to the reactive liquid phase sintering. Dielectric constant lowered from 10.15 to 9.38 and Q x fo increased up to 92000GHz with increasing LiF content.

• 환경위생공학
• /
• 제21권2호
• /
• pp.36-46
• /
• 2006

The purpose if this study was to investigate mother' oral health management behavior to their children. Two hundreds sixty seven mothers with elementary school students were surveyed among the residents living of Iksan city, Korea. A questionnaire was constructed and administered to the samples. The research focused in the following items: the subjects' socio-demographic factors such as education level and employment and so on; their knowledge of plaque; the leading causes of caries, regular dental examinations; dental treatment; their interest in their children's dental health; the frequency of the subjects examining their children's teeth; non-cariogenic food preparation, etc. Being based in collected data, mothers' oral health management behavior to their children were analyzed according to maternal socio-demographic factor and result were following. There was a difference in the subjects knowledge of dental plaque in accordance with their employment or unemployment and family income. There was no difference in mother's oral health management behavior to their children according to parents' education level, the subjects' age and family income. Most of mother answered the main reason of dental caries was that their children did not toothbrush their teeth regularly and there was a difference in the understanding of the subjects in accordance with the education level of fathers and family income. The subjects had a low understanding of the effect of preventing caries with the help of fluoride. They didn't have enough understanding of water fluoridation. So it is necessary that active campaigns should be launched to enlighten people in relation to the ways of preventing dental caries with fluoride.

• 한국광학회지
• /
• 제11권3호
• /
• pp.171-178
• /
• 2000

본 논문에서는 $1.47mu$m 증폭대역을 구현하는 툴륨이 첨가된 플루오르 고아섬유 증폭기(Thulium doped fiuoride fiber amplifier : TDFFA)를 수치 해석적 방법으로 모델링하였다. 본 모델은 상위변환(unconvenverison) 펌핑 방식을 도입하였고, $0.8\mu$m, $1.4\mu$m, $ 1.9\mu$m, $2.3 \mu$m 등의 다양한 전이 대역이 존재하는 Tm3+ 이온을 모델링하기 위하여 6개의 에너지 준위에 대한 비율식과 관계된 전이과정들을 고려하는 전파식을 사용하였고 트랜스버스 모드와 파워의 전방과 후방 전파를 고려하였다. 본 모델은 쥬드-오펠트(J-O) 이론, 에너지 캡 법칙, 맥콤보 관계 등을 이용하여 구한 TDF의 분광 파라미터들을 사용하였다. 시뮬레이션 결과는 이득과 잡음지수 등이 기존의 실험 결과와 비교하여 잘 부화된 결과를 보인다.

• International Journal of Clinical Preventive Dentistry
• /
• 제14권4호
• /
• pp.209-215
• /
• 2018

In recent years, the numbers of the orthodontic dental patients have been rapidly increased in adolescent or young adult aged generation. It has been well known that it would be very hard to control the oral hygiene cares for orthodontic applied dental patient because of the complexity of the appliance. So the caries prevalence of the orthodontic dental patients would be higher than non-appliance persons, and it might be easy to cause the dental caries especially on the labial or buccal surface of the tooth through equipping the fixed type appliance with a long period, even though the alignment of the teeth would be arranged well. So, the massive preventive program for preventive dentistry should be needed for the dental patients for orthodontic treatment, in order to protect the dental caries and the periodontal disease for them. But, lots of the dentists or dental hygienists sometimes neglect of this point for preventive dental cares orthodontic dental patients, or do not know the importance and how to manage the skill for the preventive dental works in clinical. In this article, it will be introduced the basic theories and skills for preventive cares as tooth-brushing instruction, fluoride topical application and pit and fissure sealant, scaling and professional mechanical tooth cleansing and the diet control, for the dental patients with the fixed type of the orthodontic appliance, in case by case.

• 접착 및 계면
• /
• 제16권3호
• /
• pp.116-121
• /
• 2015

본 연구에서는 발수성 재료로 쓰이고 상대적으로 가격이 비싼 불소계 실란을 대체하기 위해 octadecyltrichlorosilane (OTS)을 사용하였다. 코팅층의 기계적 접착강도를 향상시키기 위해 무기바인더를 산 촉매 하에서 졸-겔 반응에 의해 분산시켜 합성하였다. 합성된 실리카 나노입자는 나노크기의 거칠기를 제공하기 때문에 초소수성을 쉽게 얻기 어려우므로 유기용매에 의한 입자의 응집을 유도하였다. 실리카 나노입자의 적절한 크기 선택에 따라 OTS를 사용해서 표면을 소수화 시킨 후 유기용매의 양이 증가함에 따라 초소수성의 표면을 얻었고 극도의 물 반발 거동이 zero sliding angle과 함께 관찰되었다. 이러한 초소수성은 용매와의 혼합과 상관없이 유전상수가 25보다 작은 값을 가졌으며 용매 내에서 입자의 응집을 통해 유도된 초소수성 표면을 제조하는 것이 저유전상수 값에 대한 지표가 되었다.

• 공업화학
• /
• 제27권1호
• /
• pp.101-109
• /
• 2016

기존의 불산을 대체할 수 있는 평판디스플레이용 유리의 식각용액을 개발하고자 진행하였다. 본 연구과정을 통해 제안된 불산 대체 유리 식각용액은 산성불화암모늄 18~19 wt%, 황산 24~25 wt%, 물 45~46 wt%, 황산염 4~5 wt%, 규불화염 7~8 wt%로 구성되며, 사용된 식각용액의 재사용 시 보충용액으로서 해당조성의 식각용액을 전체의 5% 되게 보충함으로서 효과적으로 지속적으로 재사용이 가능하다. 개발된 식각용액은 $30^{\circ}C$에서 $5{\mu}m/min$ 이상의 식각속도를 나타내며, 반복 재사용 시에도 초기 식각액 전체 질량의 5% 추가로 보충함으로서 식각속도는 $0.1{\mu}m/min$ 이하로 편차로 식각속도가 안정적으로 유지되었다. 이 식각공정을 통해 얻어진 평판디스플레이용의 유리의 표면 상태는 Pin hole, Dimple 등이 발견되지 않는 양호한 품질을 나타내었다.

• 센서학회지
• /
• 제22권1호
• /
• pp.49-53
• /
• 2013

In this paper, we proposed a laser-based non-contact temperature measuring method for high speed rotating polycarbonate (PC) disk using transparency change of thermocolor. The thermocolor has abilities to change color and transparency due to a change in temperature. The thermocolor is applied on one side of polyvinylidene fluoride (PVDF) membrane. The thermocolor applied membrane is attached to inside of reaction chamber in disk. An optical system consisted of a laser beam radiator and a laser photometer is installed. Laser is irradiated at the bottom side of disk and the transmitted laser beam is detected by the laser photometer at the opposite side of disk. During the disk is rotating, laser is irradiated and detected simultaneously. The laser photometer senses the transmitted laser power and generates voltage as output. The temperature of disk can be detected during the disk is rotating up to 3000 RPM.

• 대한소아치과학회지
• /
• 제42권4호
• /
• pp.302-311
• /
• 2015

본 연구는 Planktonic growth inhibition test와 CDC Biofilm Reactor를 사용한 Biofilm assay를 통해 S-PRG filler를 함유하는 치면열구전색제의 S. mutans에 대한 항미생물 효과를 기존의 치면열구전색제와 비교하고자 하였다. S-PRG 필러를 함유하는 치면열구전색제인 BeautiSealant, 불소를 방출하는 치면열구전색제인 Clinpro$^{TM}$ sealant, 불소 미방출 치면열구전색제인 Concise$^{TM}$ sealant를 실험군으로 선정하였다. 성장억제평가를 위해 치면열구전색제를 사용하지 않은 군을 음성 대조군으로 설정하였으며, 3개의 실험군 모두 대조군보다 유의할 정도로 낮은 집락 형성 단위를 보였고, Clinpro$^{TM}$ sealant가 BeautiSealant와 Concise$^{TM}$ sealant보다 유의할 정도로 낮은 집락 형성 단위를 보였다. BeautiSealant와 Concise$^{TM}$ sealant 군간에는 유의한 차이가 관찰되지 않았다. 바이오 필름 평가에서도 Clinpro$^{TM}$ sealant군이 BeautiSealant와 Concise$^{TM}$ sealant군들에 비해 유의할 정도로 낮은 집락 형성을 보였으며, BeautiSealant와 Concise$^{TM}$ sealant 군간에 유의한 차이는 관찰되지 않았다. 본 연구 결과 S-PRG filler를 포함하는 치면열구전색제인 BeautiSealant는 기존의 불소방출 치면열구전색제에 비하여 낮은 항미생물 효과와 높은 바이오 필름 형성능을 보였다.

• 청정기술
• /
• 제11권3호
• /
• pp.129-139
• /
• 2005

불소 화합물인 TFEA (2,2,2-trifluoroethanol)와 HFE (hydrofluoroether)는 분자 내에 염소를 함유하지 않으므로 오존층을 파괴하지 않으며, HFC, HCFC계 세정제에 비하여 지구온난화 영향력도 낮고, 탄화수소계 세정제보다 열적으로 안정하여 차세대 CFC 대체세정제로 주목받고 있다. 이에 따라 본 연구에서는 CFC-113, 1,1,1-TCE, HCFC-141b 등의 오존파괴물질인 염소계 세정제와 차세대 대체세정제인 TFEA, HFE-7100, HFE-7200의 물성과 세정력을 비교 평가하고, 현재 대체세정제로사용하고 있는 IPA, methanol과의 물성, 세정력을 비교 평가하였다. 또한, TFEA를 기초로 하여 alcohols, HFEs와의 혼합 비수계세정제를 제조하고, 이들의 물리적 성질과 세정력을 측정하여 불소계 화합물의 대체세정제로서의 활용가능성을 평가하였다. 그 결과, TFEA와 HFEs는 현재 주요 기간산업에서 사용하는 다양한 오염물지릉 세정에서 염소계 세정제에 비하여 낮은 세정능력을 보여주었지만, 불소를 함유한 화합물이므로 불소함유 오일의 제거에는 우수한 세정력을 보였다. 또한 TFEA와 alcohols 또는 HFEs를 혼합하여 사용함으로써 플럭스와 절삭유에 대한 세정력을 100%까지 향상시킬 수 있어 불소계 화합물을 적절한 용제 또는 첨가제와 혼합하여 혼합세정제로 사용하면, 세정능력이 우수하고 환경친화적인 비수계세정제를 개발할 수 있을 것으로 기대되었다.

• Nutrition Research and Practice
• /
• 제14권2호
• /
• pp.143-151
• /
• 2020

BACKGROUND/OBJECTIVES: The nutrition of the elderly depends on various factors. Oral health, especially oral dryness, can be an important risk factor. In this study, we attempted to determine whether dry mouth is associated with compromised nutrient intakes. SUBJECTS/METHODS: A total of 120 participants aged 65-86 yrs (mean age: 69 ± 1 y) were included in this study. Demographic and health-related characteristics, living status, meals, number of medications, medical conditions, chewing ability, and quality of life, the Oral Health Impact Profile (the OHIP-14) were assessed. We performed one day 24-hr recall assessment for nutrient analyses. The differences of the means between the dry-mouth and non-dry-mouth groups were analyzed. Elderly subjects with xerostomia-induced dry mouth were classified as those who reported at least one dryness symptom on a questionnaire. RESULTS: A significant difference in population distribution was observed among the elderly who took medications for hypertension, diabetes and osteoporosis and was significantly higher in the dry-mouth group (70.2%) than in the non-dry-mouth group (44.4%) (P = 0.005). Compared with the non-dry-mouth group (50.8%), a significantly higher proportion (73.7%) of participants in the dry-mouth group took multiple medicines (≥ 4 medications) (P = 0.019). The intakes of vegetable fat, vitamin E, folate and water in the dry-mouth group were lower than in the non-dry-mouth group. The intakes of fluoride and ω-3 fatty acids were significantly lower in the dry-mouth group than in the non-dry-mouth group. CONCLUSION: The participants in the dry-mouth group exhibited low nutrient and water intakes. It is recommended that the elderly with dry mouth should drink sufficient water and receive targeted and specific nutritional guidance to prevent malnutrition.