• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.939-942
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• 2007

Vacuum cleaner is a close life product that can remove various dusts from our surroundings. However well vacuum cleaner clean our environments, many people are looking away from it, due to its loud noise. Its noise causes a big trouble in the usual life, for example, catch calls, TV watching and discussing etc. To reduce these inconveniences, noise reduction methods and systematic design of low noise vacuum cleaner are studied in this paper. At first, sound quality investigation is performed to get the noise level and quality that make people TV watching and catch calls available. Based on the European and domestic customer SQ survey result, sound power, peak noise level and target sound spectrum guideline are studied and introduced. As a second, precise product sound spectrums are designed into each part based on the sound quality result. Fan-motor, brush, mainbody, cyclone spectrums are decided to get the final target sound based on the contribution level. Fan-motor is the major noise source of vacuum cleaner. Specially, its peak sound, RPM peak and BPF Peak, cause the people nervous. To reduce these peak sounds, high rotating impeller and diffuser are focused due to its interaction. A lot of experimental and numerical tests, operation points are investigated and optimization of flow path area between diffusers is performed. As a bagless device, cyclones are one of the major noise sources of vacuum cleaner. To reduce its noise, previous research is used and adopted well. Brush is the most difficult part to reduce noise. Its noise sources are all comes from aero-acoustic phenomena. Numerical analysis helps the understanding of flow structure and pattern, and a lot of experimental test are performed to reduce the noise. Gaps between the carpet and brush are optimized and flow paths are re-designed to lower the noise. Reduction is performed with keeping the cleaning efficiency and handling power together and much reduction of noise is acquired. With all above parts, main-body design is studied. To do a systematic design, configuration design developments technique is introduced from airplane design and evolved with each component design. As a first configuration, fan-motor installation position is investigated and 10 configuration ideas are developed and tested. As a second step, reduced size and compressed configuration candidates are tested and evaluated by a lot of major factor. Noise, power, mass production availability, size, flow path are evaluated together. If noise reduction configuration results in other performance degrade, the noise reduction configuration is ineffective. As a third configuration, cyclones are introduced and the size is reduced one more time and fourth, fifth, sixth, seventh configuration are evolved with size and design image with noise and other performance indexes. Finally we can get a overall much noise level reduction configuration. All above investigations are adopted into vacuum cleaner design and final customer satisfaction tests in Europe are performed. 1st grade sound quality and lowest noise level of bagless vacuum cleaner are achieved.

• 한국재료학회지
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• 제20권11호
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• pp.617-622
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• 2010

We have studied methods to save Si source during the fabrication process of crystalline Si solar cells. One way is to use a thin silicon wafer substrate. As the thickness of the wafers is reduced, mechanical fractures of the substrate increase with the mechanical handling of the thin wafers. It is expected that the mechanical fractures lead to a dropping of yield in the solar cell process. In this study, the mechanical properties of 220-micrometer-solar grade Cz p-type monocrystalline Si wafers were investigated by varying saw-damage etching conditions in order to improve the flexural strength of ultra-thin monocrystalline Si solar cells. Potassium hydroxide (KOH) solution and tetramethyl ammonium hydroxide (TMAH) solution were used as etching solutions. Etching processes were operated with a varying of the ratio of KOH and TMAH solutions in different temperature conditions. After saw-damage etching, wafers were cleaned with a modified RCA cleaning method for ten minutes. Each sample was divided into 42 pieces using an automatic dicing saw machine. The surface morphologies were investigated by scanning electron microscopy and 3D optical microscopy. The thickness distribution was measured by micrometer. The strength distribution was measured with a 4-point-bending tester. As a result, TMAH solution at $90^{\circ}C$ showed the best performance for flexural strength.

• 한국환경보건학회지
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• 제39권5호
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• pp.456-464
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• 2013

Objectives: The aim of this study was to investigate the microbial contamination levels in elevators in apartment buildings and to provide information on such microbial contamination. Methods: A total of 144 samples, including from the exterior buttons, interior buttons, elevator handrails, walls, ventilators and airborne bacteria were collected in the morning and afternoon from July to August 2013 for six different elevators. The samples were used to detect sanitary indicator bacteria (total bacteria, coliform, and Escherichia coli), pathogenic bacteria (E. coli O157, L. monocytogenes, Salmonella spp., B. cereus, S. aureus) and fungi. Results: Contamination levels of total bacteria were 0.3-3.8 and 0.0-2.4 log CFU/100 $cm^2$ in the morning and afternoon, respectively. In the case of coliform bacteria, the levels were 0.0-3.7 log CFU/100 $cm^2$ in the morning and 0.0-0.3 log CFU/100 $cm^2$ in the afternoon. However, E. coli was not detected among all samples. Bacillus cereus, pathogenic bacteria, was only detected in 13 (11%) among 144 samples. E. coli O157, L. monocytogenes, Salmonella spp. and S. aureus were not detected among all samples. Comparing the samples collected in the morning and afternoon, we could confirm that the samples in the afternoon were cleaner. Conclusions: This study indicates that the samples in the afternoon were cleaner because these samples were collected following routine cleaning. Also, the levels of contamination in the elevators were low and the sanitary conditions were comparatively well-managed. Therefore it is deemed necessary for elevators be cleaned regularly to provide good conditions for people using elevators.

• 한국치위생학회지
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• 제12권2호
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• pp.379-389
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• 2012

Objectives : The purpose of this study was to improve the practice level on dental hygienists'infection prevention by examining the actual condition of dental hygienists'infection control and analyzing factors of having influence upon this. Methods : A questionnaire survey was carried out from July 18, 2011 to August 26 targeting dental hygienists who work at medical institutions where are located in Daegu, Busan and Ulsan Metropolitan Cities and Gyeongsangnam buk-do. After then, the following conclusions were obtained. Results : 1. As a result of surveying practice by item in the practice level of infection prevention, the items with high practice level in the management of infectious diseases were surveyed to be 12 months(89.6%) for health-checkup cycle and to be having experience of vaccination(78.0%) for hepatitis type B. The items with high practice level in the management and practice of washing hands were indicated to be in order of regularly paper towel(87.7%) and hands cleaning after regular medical examination(80.5%). In the item of the practice on wearing and managing individual protection equipment, regularly wearing(93.1%) rubber globes given washing implements was indicated to be high. 2. As a result of analyzing working career, working institution, working region, and practice level of infectious-disease management, the appearance of fulfilling infection control guidelines at medical institution and the experience of education for infection control were indicated to have difference depending on working institution. Regularly health checkup was indicated to have difference depending on respondents' working career and working institution. 3. The whole average in the practice level of infection prevention according to working career, working institution, and working region was indicated to be 2.55 out of 3-point perfection. 4. Wearing latex gloves was indicated to have statistically significant difference depending on working institution(p<0.001) and working region(p<0.001). The exchange of latex gloves every patient and the use of paper apron had statistically significant difference depending on working region(p<0.001). 5. As a result of comparing the frequency of using protection equipment for preventing infection according to the management of infectious diseases, the statistically significant difference was shown depending on the appearance of infection control guidelines at medical institution(p<0.001), the appearance of having experience of health checkup(p<0.01), and the appearance of having experience of vaccination for hepatitis type B(p<0.05). Conclusions : The above-mentioned findings showed that the denture satisfaction of the denture-wearing senior citizens was linked to their subjective oral health awareness. Therefore it will be possible to improve denture-wearing elderly people's quality of life when oral health plans geared toward boosting their denture satisfaction are carried out.

• 대한환경공학회지
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• 제22권3호
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• pp.523-533
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• 2000

본 연구는 재래식 혐기성 공법에 비해 메탄회수율과 처리효율이 우수한 막분리형 이상 혐기성 반응시스템을 개발하여 산생성 반응조의 미생물 체류시간을 증대시키고 시스템 운전효율을 향상시키기 위해 수행하였다. Pilot plant 운전에 사용된 막은 셀룰로오스 계통으로 $0.5{\mu}m$의 막공경과 $0.8m^2$의 유효 표면적을 가졌으며 메탄발효조는 UASB와 AF로 구성되어 있다. 혐기성 침지형 반응조를 운전한 결과 COD 제거율은 70~80%, 생성가스 중 메탄함율은 90%까지 향상시킬 수 있었다. Pilot plant 운전동안 막의 케이크 저항이 중요한 막오염원으로 나타남에 따라 이를 최소화하기 위해 세가지 공경 (40, 53, $63{\mu}m$)을 가진 전처리 필터로 적용하였다. 적용된 prefilter중 $63{\mu}m$ 전처리 필터의 경우가 가장 효과적으로 케이크 저항을 줄이고 막 유속을 증가시켜 50일 이상 장기운전을 가능케 하였다. 또한 장기 운전으로 인한 막 오염물질은 산과 알카리 세척용액에 의해 연속적으로 세척함으로써 최초 막유속의 89% 까지 회복할 수 있었다.

• 한국안광학회지
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• 제15권4호
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• pp.319-328
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• 2010

목적: 안경광학과 임상실습의 현황 및 실태를 파악하여 임상실습의 효율적 운영과 질적 개선을 위한 자료를 얻고자 하였다. 방법: 전국의 30개 안경광학과를 대상으로 임상실습 현황에 대한 설문조사를 하였고 이중 4개 대학에서 161명의 학생으로부터 임상실습 실태에 대한 설문조사를 실시하였다. 결과: '임상실습을 위한 구체적 프로그램'이 마련되지 않은 곳은 60.7%였다. 대부분의 대학에서 임상실습을 졸업학점에 반영(96.4%)하였고, 각 대학의 임상실습에 관한 교과목명과 해당학점은 다양하였다. 실습 학생들에게 임상실습 수행 중 가장 어려웠던 사항은 '고객응대'였고 임상실습의 주 업무는 '안경원 청소 및 안경테와 도구정리'였다. 임상실습을 통해 가장 유익했던 점은 '안경업계 현실파악'이었다. 임상실습 전과 후의 진로 비교에서 '안경원'과 '안경/콘택트렌즈 관련업체'의 선호도는 감소하고 '안과 병의원'과 '전공과 관련 없는 일'의 선호도는 높아졌다. 결론: 안경광학과 임상실습의 효율적 운영과 학생들의 만족도를 높이기 위한 폭 넓은 연구와 학교와 실습업체 간의 긴밀한 협조와 관심이 요구된다.

• 한국의료질향상학회지
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• 제8권1호
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• pp.10-21
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• 2001

Background : The Clostridium difficile is the most important identifiable cause of nosocomial infectious diarrhea and colitis, which lengthens hospital stay. Recently incidence of C. difficile has been increasing in an university hospital, and an intervention for prevention and control of C. difficile associated diarrhea (CDAD) was in prompt need. Methods : Subjects were the patients in the neurosurgical intensive care unit(NCU) where C. difficile was most frequently isolated. To increase participation of various departments, we used the CQI method, because management of CDAD requires a wholistic approach including control of antibiotics, barrier precaution and environmental cleaning and disinfection. Duration of the CQI activities was 9 months from April to December 1999. Results : The identified problems were misuse and overuse of antibiotics, lack of consciousness of medical personnels and the possibility of transmission from the contaminated environment and tube feeding. Education for proper use of antibiotics and management of C. difficile infection, use of precaution stickers, supplement of handwashing equipments, emphasis on environmental disinfection, and the change of the process of tube feeding were done. The CDAD rate in NCU was significantly decreased after the CQI program (8.6 case per 1,000 patient days from January to April 1999 vs 4.8 from May to December 1999). The distribution of neurosurgical wards including NCU among the total number of isolated C. difficile from the clinical specimens dropped from 49.4% in January to April to 33,7% in May to December. The average hospital stay of the neurosurgical department changed from 19.6 days to 15.2 days. Also, the effect of the CQI activities for C. difficile may have affected the incidence of vancomycin resistant enterococci (VRE). Duration and dosage of certain antibiotics used in the NS department were decreased. The distribution of neurosurgical department in the number of VRE isolated patients declined from 18.4% to 11.1%. Conclusion : Infection control of resistant organisms such as C. difficile is likely to be successful when management of environmental contamination an collaborative efforts of decreasing the patients' risk factors such as antibiotics management and decreasing the length of hospital stay come simultaneously. For this work, related departments need to actively participate in the entire process under a common target through discussions for identifying problems and bringing up solutions. In this respect, making use of a CQI team is an efficient method of infection control for gathering participation and cooperation of related departments.

• 보존과학연구
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• 통권34호
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• pp.50-61
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• 2013

사천 구암 발굴현장 내 출토된 조선시대 회곽묘에서 복식류와 함께 미투리가 출토되었다. 미투리는 목재와 초본류로 제작된 복합재질로 앞총부가 소실되거나 매우 약한 상태로 수습되었다. 보존처리를 위하여 미투리에 대한 과학적 재질분석과 강화제 선정 예비실험을 먼저 진행하였다. 재질 분석 결과, 미투리는 벼속(Oryza spp.), 마섬유, 쌍자엽식물 1종이 사용됨을 확인하였으며 또한 뒤쪽 도갱이에 붙어있었던 직물은 면섬유로 분석되었다. 강화제 선정을 위해 약품 5종(Polyethylene Glycol, Paraloid-B72, Dammar gum, Methyl Cellulose, Silicone resin)을 선정하여 예비실험을 실시하였다. 색차, 광택성, 내절강도와 인장강도 변화를 약품별로 측정하여 결과를 비교하여 PEG를 강화제로 선정하였다. PEG는 색도 및 광택변화가 적고, 인장강도가 높게 확인되어 가장 적합한 것으로 판단되었다. 미투리 보존처리는 클리닝 후 PEG 4000을 5%에서 80%까지 농도를 높여 유물에 견고성을 부여하였으며 조절건조를 통해 보존처리를 완료하였다.

• 대한간호학회지
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• 제28권3호
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• pp.705-717
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• 1998

Ostomates have suffered from many difficulties due to their physical, psychosocial handicaps and changes of life style to include ostoma management that influences their daily and quality of life. An appropriate nursing education for ostoma management is very important. Practical educational materials needs revision because those were developed by pharmaceutical companies and hospital institutions. The purpose of this study is to provide more practical and reasonable education materials for ostomates by doing analysis and survey of educational materials now being used. We surveyed 8 types of educational materials used in 23 university hospitals and medical centers in Seoul ; four of them were developed by department of nursing and the remainder by an Ostomy Company Data, collected from July 14, 1997 through July 31, 1997 were analyzed. The results are as follows ; 1. The analysis of education guide, on ostomate included 14 subcategories : introduction, structure and function of gastrointestinal tracts, definition of stoma, types of ostomy, definition of peristalsis, methods of defecation management, selection of instrument, resolution of problems and general situations following surgery, daily life, where to ask for help, explanations for terms, information about where to buy instrument, explanations for enterostomal therapist, a matter of consultation with doctor, etc. 2. Introduction contained specific contents on practical ostomate management that ostomates would experience through their lives. Ostomate education guides were developed 3 hospitals except one which missed this point. 3. Most ostomate education guides, except one hospital, helped ostomates to understand their physical structure changes with specific explanations on gastrointestinal tracts with figures. 4. Six institutions did not talk about the definition of peristalsis. 5. All institutions, except two, helped ostomates to understand types of ostomy with figures. 6. More detailed explanations on natural defecation are needed. The benefits and pitfalls of natural defecation should be more specified. 7 No psychosocial difficulties of ostomy management were addressed. 8. The efficiency of enema can be better understood through all explanations with figures. Some institutions did not mention items about definition, benefits, pitfalls of enema, sequency of enema, how to wash, cautions performing and enema, skin management, cleaning instrument after enema proper time to spend. 9. There were no detailed contents and what to do in case of not being able to do enema. 10. Only one educational material mentioned emotional aspects after the surgrey. 11. Most institutions explained subcategory of daily life but did not provide specific contents on the difficulties of physical, psychological, and sociocultural controls. 12. The subcategory of ureterostomy education guides included explanations on normal structure and function of urinary tracts, types of ureterostomy, how to manage skin, usage and types of instrument, commercial urostomy, how to manage instrument, daily life, introduced the general contents. However, more specific explanations were needed.

• Journal of Periodontal and Implant Science
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• 제50권5호
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• pp.340-354
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• 2020

Purpose: This pilot study was conducted to evaluate the cleaning efficacy of an angled implant brush for home oral hygiene of full-arch fixed-implant prostheses. Methods: Forty-one patients treated with a full-arch implant rehabilitation in the maxilla or mandible (164 implants) for at least 4 months were enrolled. The screw-retained fixed prostheses were removed and baseline (T0) parameters were recorded, including plaque index (PI), probing depth (PD), and bleeding on probing (BOP). All patients completed a 5-item questionnaire on hygiene maintenance and received an implant brush for home hygiene. After 1 month (T1) PI, PD, and BOP were recorded again and patients completed a 7-item questionnaire to evaluate their satisfaction with the implant brush. One-way repeated-measures analysis of variance was conducted to evaluate the significance of changes in PI, PD, and BOP. A P value <0.05 was considered to indicate statistical significance. Results: A statistically significant reduction of BOP (0.62±0.6 at T0 vs. 0.5±0.5 at T1; P=0.032) was found, while no statistically significant changes in PD (1.74±0.5 mm at T0 vs. 1.77±0.5 mm at T1; P=0.050) or PI (1.9±0.7 at T0 vs. 1.7±0.7 at T1; P=0.280) occurred. According to the 7-item questionnaire, patients reported no difficulty in using the angled brush (63.4%) and deemed it highly (46.3%) or very highly (4.8%) effective in improving their home oral hygiene. Conclusions: Within the limits of the present pilot study, the patients experienced a reduction of BOP 1 month after being instructed to use the angled implant brush. The angled implant brush appeared to be a well-accepted device for home-care hygiene of full-arch fixed-implant rehabilitations.