• Journal of Ocean Engineering and Technology
• /
• v.27 no.2
• /
• pp.114-120
• /
• 2013

A superhydrophobic surface means that the contact angle between the solid surface and a water droplet is more than $150^{\circ}$. Materials with a superhydrophobic surface have a self-cleaning function because of the Lotus effect, in which water is not absorbed by the material but rolls off of it. If such a Lotus effect can be applied to the surface of underwater vessels, submarines, torpedos, and so on, enhanced vessels can be made based on this lubricant effect reducing the friction coefficient for the liquid. Because polymer composites can be easily applied in various nanotechniques, they are more advantageous than conventional materials like iron in terms of a superhydrophobic surface. Furthermore, a superhydrophobic surface bring enhanced anticorrosion and ecotechnology because no paint is needed on underwater vessels.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2012.05a
• /
• pp.153-153
• /
• 2012

자연계에는 다양한 생물체들의 표면 구조가 특수한 기능을 갖는 형태로 되어 있다. 이와 같이 특수한 기능을 갖는 생물체들의 표면 구조는 일반적으로 화학적 조성과 표면의 더불어 나노와 마이크로 구조가 혼합되어 있는, 이른바 hierarchical 구조를 보인다. 그 중에서도 표면 초소수성 특성을 보이는 연잎의 표면과 같은 hierarchical 구조는 self-cleaning effect 등의 기능성 표면 제작에 활용이 가능하여 이를 모사하기 위한 연구가 활발히 진행중에 있다. 이에 본 연구에서는 연잎과 같은 초소수성을 띄는 ZnO nano-in-micro hierarchical 구조를 저온 공정을 통하여 다양한 기판에 제작하였다. 이를 위하여 ZnO 나노 입자 분산 레진을 제작하였고 UV imprinting 과 수열합성법을 통하여 마이크로 패턴 상부에 ZnO 나노 입자가 형성된 ZnO nano-in-micro hierarchical 구조를 형성하였다. 제작된 ZnO hierarchical 구조의 젖음 특성은 표면 접촉각이 $160^{\circ}C$이상인 초소수성을 보였으며, 제작 공정에는 고온의 열처리가 수반되지 않아 PET film 등 다양한 기판에 ZnO hierarchical 구조를 제작할 수 있었다.

• Journal of dental hygiene science
• /
• v.16 no.6
• /
• pp.409-414
• /
• 2016

The purpose of this study was to evaluate the antibacterial effect of tea tree oil in denture cleaners. A self-curing denture resin was used to make the experimental specimen ($12mm{\times}2mm$). A saline solution was used as the control. To observe surface changes after cleaning, the microhardness and color of the experimental specimen's surface were analyzed. For the antibacterial activity test, Candida albicans was used. The microhardness and color of the surface remained unchanged after cleaning. The result of the antibacterial activity test revealed that the tea tree oil-containing solutions had a more enhanced antibacterial effect than did the saline solution. Therefore, these results suggest that the tea tree oil-containing solution is a promising denture cleaners.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.17 no.2
• /
• pp.15-25
• /
• 1989

The purpose of this study was to supply data of resident′s participation direction about children′s playground management. In this study, use disposition and consciousness of resident about management are investigated and analyzed at the 5 children′s playground in Taegu city. The results of this study were as follows: The result of resident′s use disposition showed ; visiting frequency was "everyday or occasionally(53.5% )", and visiting purpose was "for children(47.9 %), for rest, sports, spare time(24.6%)" and visiting time was equal1y except forenoon, and staying time was "within 1 hour(73.1%)". The satisfaction about park facilities and park existence of residents′ is composed importance degree of which is convenient, manyfunction spaces, managemental of tree and facilities in order. 9.3% of residents were proposal experience about management, and concern ratio of circumferenmce showed highly "concerned answer(45.9%)" About consciousness ratio of management subject, 46.5% of residents depended on authorities leading. Wholly, recognition ratio showed low. Park administration of authorities leading and lack of resident′s concern wore thought as its problem. About experience of cleaning beautification rout children′s playground, 14.2% of residents answered "be experience". Participation type of desirous management showed highest "cleaning of fallen leaves and rubbish(22.7% )". So, residents wished to take part in such simple managements. Charge of necessary tool and cost for management showed highest "partial charge of residents (47.9% )". About participant ratio of self government activity made by residents, 75.1% of residents answered "don′t be participated". A reason of nonparticipation showed "insufficiency of place and opportunity (38.7%), deficiency of time(17.97)". Activity of initiative and existing group can be done as a fine device in future. Desirous events for children and residents showed highest "play guidence for children or meeting for aged milan(40.7% )". Therefore, it will have to consider enough about resident′s participation program for activity of use and efficient management of children′s playground.

• Korean journal of food and cookery science
• /
• v.25 no.6
• /
• pp.677-689
• /
• 2009

The purpose of this study was to evaluate food safety practices and knowledge of foodservice workers at senior welfare centers. A self-administrated questionnaire was administered to 1200 foodservice workers at senior welfare centers in Seoul, Incheon and Gyeonggi province. Two hundred five responses were returned, with 181 usable for analysis. Statistical analyses were conducted using SPSS for Windows(ver.14.0). Volunteers of respondents comprised 64.1% while chefs and employees comprised 20.9%. Food safety practices were assessed using a 5-point scale(1: strongly disagree - 5: strongly agree), and the average score of food safety practices was 4.27. For specific practices, 'personal hygiene (4.46)' scored the highest, followed by 'cleaning and sanitizing(4.43)', 'separate handing(4.40)', 'cooking process(4.11)', and 'receiving and storing(4.05)'. There were significant differences in the practice average score by age(p<0.01) and experience of food safety education(p<0.01). The total score for food safety knowledge was 14.43 out of 20 points. In the category of food knowledge, 'equipment and facility(80.5%)' had the highest correct answer rate, followed by 'personnel hygiene(75.9%)', 'cooking process(70.4%)', and 'cleaning sanitizing(65.8%)'. There were significant differences in the knowledge total score by job type(p<0.05), age(p<0.05), working experience(p<0.05), chef certification (p<0.01), and frequency of food safety education(p<0.01). The knowledge and practice scores were significantly correlated(p<0.01). This study suggests that food safety education for foodservice workers should be conducted continuously and repetitively, and the development of proper education materials is needed to improve the effectiveness of food safety education for chefs, employees and volunteers at senior welfare centers.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.1
• /
• pp.109-115
• /
• 2013

This study targeted 501 the elderly ages 65 or over in three places including the Senior Welfare Center and the college for seniors located in Daegu City and Gyeongsangbuk-do. The study results on the preference for oral health care management items across different ages showed that the age group of 65~69 fluoride application; the age group of 65~74 scaling and education of brushing; the age group of 70~74 denture cleaning and maintenance; the age group of 75 denture production. In the relationship between the self-perceived oral condition and the items of oral health care management, respondents who currently have a poor oral condition or have greater chewing trouble, or have higher dry mouth, preference the manufacturing of dentures in most cases. Respondents who have a lower number of teeth or wear dentures preference dentures cleansing and management in most cases. Respondents who have shaking teeth or have frequent tooth pain preference tooth extraction. Since the preference for oral health care management items may differ by their age or oral condition, oral health management customized to each individual should be applied.

• Journal of Korean society of Dental Hygiene
• /
• v.16 no.3
• /
• pp.373-381
• /
• 2016

Objectives: The purpose of the study is to investigate the awareness toward use and service contents of long term care for the elderly. Methods: A self-reported questionnaire was completed by 296 adults from August 13 to October 20, 2014. The questionnaire consisted of general characteristics of the subjects, awareness toward long term care insurance for the elderly, awareness toward long term oral health care services, use of long term care service and use intention for the long term care insurance. Data were analyzed by SPSS 18.0 program. Results: Those who were aware of the long term care insurance accounted for 55.4 percent. Approximately 50 percent of the respondents recognized long term care service items, home visit care, home visit bathing, and home visit nursing. Most of the respondents had information of long term care services by way of mass media and direct contact. Only 13.4 percent of the respondents were aware of the oral health service in the long term care insurance. The subjects were aware of denture cleaning, oral cleaning and oral health education out of oral health service in order; and oral health services that needed to be offered were denture cleaning, oral health education and professional toothbrushing. They reported that dental hygienists were the most important manpower that offered the efficient oral health care services. They answered that professional manpower and financial support are required for oral health services. The positive thinking to long term care insurance accounted for 89.2 percent and 91.3 percent had use intention for oral health services. Conclusions: Many elderly people have mastication or dysphagic problems due to systemic diseases. Therefore, it is necessary to announce the long term care insurance and long term care services for the elderly people.

• Korean Journal of Materials Research
• /
• v.4 no.1
• /
• pp.9-23
• /
• 1994

Epitaxial $CoSi_2$ layer has been grown on NaCl(100) substrate at low deposition temperature($200^{\circ}C$) by multitarget bias cosputter deposition(MBCD). The phase sequence and crystallinity of deposited silicide as a function of deposition temperature and substrate bias voltage were studied by X-ray diffraction(XRD) and transmission electron microscopy(TEM) analysis. Crystalline Si was grown at $200^{\circ}C$ by metal induced crystallization(M1C) and self bias effect. In addition to, the MIC was analyzed both theoretically and experimentally. The observed phase sequence was $Co_2Si \to CoSi \to Cosi_2$ and was in good agreement with that predicted by effective heat of formation rule. The phase sequence, the CoSi(l11) preferred orientation, and the crystallinity had stronger dependence on the substrate bias voltage than the deposition temperature due to the collisional cascade mixing, the in-situ cleaning, and the increase in the number of nucleation sites by ion bombardment of growing surface. Grain growth induced by ion bombardment was observed with increasing substrate bias voltage at $200^{\circ}C$ and was interpreted with ion bombardment dissociation model. The parameters of $E_{Ar}\;and \alpha(V_s)$ were chosen to properly quantify the ion bombardment effect on the variation in crystallinty at $200^{\circ}C$ with increasing substrate bias voltage using Langmuir probe.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.29 no.2
• /
• pp.111-118
• /
• 2023

In this study, the feasibility of laser patterning on the surface of food packaging polymer film was confirmed, and the surface patterning process conditions of femtosecond laser were established. In addition, it was proved that the surface properties of the film can be changed and controlled through the fabrication of various patterned films on the surface of food packaging films such as HDPE, PP, and PET. Various patterned surfaces, including large-scale circular patterns induced by a single femtosecond laser pulse, roughness patterns achieved by overlapping single pulses by 30%, straight line patterns, roughness patterns obtained by overlapping straight line patterns, and grid patterns formed by intersecting straight line patterns were fabricated. The characteristics of the patterned HDPE, PP, and PET films, based on the surface pattern structure and size, were analyzed using SEM, AFM, and contact angle measurements. Compared to the surface of each control film without femtosecond laser patterning, the contact angles of the surfaces of large-area circular patterning HDPE and PP films, large-area roughness patterning HDPE and PP films by overlapping 30% of single pulses, and large-area roughness patterning PET film by overlapping rectilinear patterning were in the range of 27.1-37.5 degree. This indicated that the HDPE, PP, and PET films became more hydrophilic after patterning. On the other hand, the HDPE film patterned with a large-scale grid pattern exhibited a contact angle of 120.4 degree, indicating that the HDPE film became more hydrophobic after patterning. Therefore, films that have been changed to hydrophilic surfaces through patterning can be used in anti-fouling applications where proteins, cells, viruses, and other food materials do not adhere or are easily detached. In addition, if a superhydrophobic surface of 150 degrees or more is fabricated through more precise lattice patterning in the future, it will be possible to use it for superhydrophobic surface applications such as self-cleaning.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.11 no.2
• /
• pp.120-129
• /
• 2023

Marine structures are subject to damage not only from sea salt but also from the adhesion of marine microorganisms and suspended particles, which cause additional damages. In order to prevent this, periodic coating is employed in the case of vessels to maintain the necessary performance. However, it is true that periodic coating is difficult for concrete or steel support structures, and there is a risk of marine environmental pollution. In this study, authors developed an anti-fouling coating agent using eco-friendly materials that possess hydrophilic cellulose nanofibers and AKD(alkyl ketene dimer). To achieve a homogeneous mixture, the content of cellulose nanofibers was fixed at 1 %, and AKD, distilled water, and waste glass were mixed using a digital mixer and homogenizer. The contact angle of the prepared coated surface was observed to be over 130°, indicating sufficient performance even in a water droplet flow test with a 15° slope, suggesting self-cleaning capability. Furthermore, through the analysis of viscosity characteristics at different temperatures, it was confirmed that the application is feasible at room temperature. Microstructure analysis also verified that the coating agent is uniformly applied to the concrete surface.