• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.3
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• pp.193-201
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• 2006

This study was performed to investigate employee exposures to waste anesthetic gases, such as enflurane and sevoflurane in operating rooms of general surgical, children's and dental clinics of a large hospital located in Seoul and to analyze factors affecting the concentrations of waste anesthetic gases. The results of the study are summarized below. 1. Based on results of personal and area samples for airborne enflurane, all of the employees investigated in this study were exposed to airborne enflurane concentrations below the ACGIH-threshold limit value (TLV) of 75 ppm. 2. However, based on results of personal samples for sevoflurane, employees of two (2) out of eleven (11) operating rooms were exposed to sevoflurane concentrations in excess of the NIOSH recommended exposure limit (REL) of 2 ppm. A similar trend was found in the area samples. 3. To investigate the source of sevoflurane emissions, airborne sevoflurane concentrations were measured on an anesthesia machine, a drug cabinet and a desk. It was indicated that the geometric means were 0.93 ppm, 0.83 ppm and 0.72 ppm, respectively. 4. Factors affecting waste anesthetic gas concentrations were the age of anesthesia machine, the volume of operating room and the extent of ventilation (p<0.05). 5. It is recommended that the use of anesthesia equipments be properly controlled, the operating room be well ventilated, and the airborne concentrations of anesthetic gases be continuously monitored.

• Resources Recycling
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• v.16 no.3 s.77
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• pp.3-11
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• 2007

Presently, most of gold is smelted from gold concentrates and anode slimes. Anode slimes are by-products of nonferrous smelters such as lead and copper. In addition, gold is recovered from waste dental and medical materials, waste gold coating solution, and waste printed circuit boards (waste PCBs). The smelting method of gold from gold concentrates and various wastes containing high concentration of gold is largely divided into chlorination, cyanidation, and amalgamation methods. For the anode slimes, electrolysis method is usually used, which largely consists of roasting, high temperature melting and electrolysis processes. Also, various wastes containing low concentration of gold are mainly treated by pyrometallursical processes. In the paper, current status on gold smelting technology is reviewed, and a novel process for gold smelting which is researched in the recent is briefly introduced.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.45 no.6
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• pp.332-342
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• 2019

Objectives: Socket grafting is vital to prevent bone resorption after tooth extraction. Several techniques to prevent resorption have been described, and various bone graft substitutes have been developed and used with varying success. We conducted this pilot study to evaluate the performance of nanohydroxyapatite (nHA) derived from chicken eggshells in socket preservation. Materials and Methods: This was a prospective, single center, outcome assessor-blinded evaluation of 23 sockets (11 patients) grafted with nHA and covered with platelet-rich fibrin (PRF) membrane as a barrier. Bone width and radiographic bone density were measured using digital radiographs at 1, 12, and 24 weeks post-procedure. Postoperative histomorphometric and micro-computed tomography (CT) evaluation were performed. The study protocol was approved by the Institutional Ethics Committee. Results: All patients had uneventful wound healing without graft material displacement or leaching despite partial exposure of the grafted socket. Tissue re-epithelialized with thick gingival biotype (>3 mm). Width of the bone was maintained and radiographic density increased significantly with a trabecular pattern (73.91% of sockets) within 12 weeks. Histomorphometric analysis showed 56.52% Grade 3 bone formation and micro-CT analysis revealed newly formed bone with interconnecting trabeculae. Conclusion: Use of a PRF membrane with nHA resulted in good bone regeneration in sockets. Use of a PRF membrane prevents periosteal-releasing incisions for primary closure, thereby facilitating the preservation of keratinized mucosa and gingival architecture. This technique, which uses eggshell-derived nHA and PRF membrane from the patient's own blood, is innovative and is free of disease transfer risks. nHA is a promising economic bone graft substitute for bone regeneration and reconstruction because of the abundant availability of eggshell waste as a raw material.

• Biomaterials and Biomechanics in Bioengineering
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• v.4 no.1
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• pp.21-32
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• 2019

Eggshell is a waste material after the usage of egg. In this work, biowaste chicken eggshells were used for preparing carbonated hydroxyapatite (HA) nanoparticles of high purity through aqueous precipitation method at room temperature. The eggshell-derived HA will be a cost-effective bioceramics for biomedical applications and an effective material-recycling technology. Additionally, mulberry leaf extract was used as a template to regulate the morphology, size and crystallinity of HA, and the effects of pH value were also examined. Characterization of the samples was performed by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Scanning electron microscopy (SEM) was used to determine the size, shape and morphology of HA. The results indicate that only one phase of HA were synthesized in the both absence and presence of mulberry leaf extract at pH of 7 and above, while DCPD or DCPA/DCPD phase was observed at pH 4 condition. The crystallite sizes of the HA samples obviously decreased when adding mulberry leaf extract as a template, while they decreased gradually as the solution pH levels increased. With increasing pH level from 7 to 14, the rod-like HA nanoparticles gradually changed to spherical shape at pH 14. Note that, the obtained product is Mg and Sr containing A- and B-type carbonate HA at alkaline pH and it can be a potential material for biomedical applications.

• Advances in nano research
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• v.17 no.2
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• pp.109-124
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• 2024

In the era of smart manufacturing, precise prediction of springback-a common issue in ultra-thin sheet metal forming- and forming limits are critical for ensuring high-quality production and minimizing waste. This paper presents a novel approach that leverages the Internet of Things (IoT) and Artificial Neural Networks (ANN) to enhance springback and forming limits prediction accuracy. By integrating IoT-enabled sensors and devices, real-time data on material properties, forming conditions, and environmental factors are collected and transmitted to a central processing unit. This data serves as the input for an ANN model, which is trained with crystal plasticity simulations and experimental data to predict springback with high precision. Our proposed system not only provides continuous monitoring and adaptive learning capabilities but also facilitates real-time decision-making in manufacturing processes. Experimental results demonstrate significant improvements in prediction accuracy compared to traditional methods, highlighting the potential of IoT and ANN integration in advancing smart manufacturing. This approach promises to revolutionize quality control and operational efficiency in the industry, paving the way for more intelligent and responsive manufacturing systems.

• Journal of dental hygiene science
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• v.13 no.3
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• pp.254-263
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• 2013

This study is to develop an evaluation index for infection control and to verify its validity by examining each set of weighted data collected from 121 infection control personnel at dental hospitals who agreed to the preliminary survey and advisory. The study was conducted from 14th December, 2010 to 31st January, 2011, and PASW Statistics 18.0 and AMOS 5.0 had been used for the statistical data analysis. As a result of the study, five evaluation factors with 21 sub-indicators have been identified at structural level, eight evaluation factors with 32 sub-indicators at processing level, and one evaluation fact with five sub-indicators at resulting level, total 14 evaluation factors with 58 sub-indicators throughout all levels. The path analysis added on the result that 'standard precautions ($x_1$)', 'infection control support system ($x_2$)', 'internal and external characteristics ($x_3$)' are exogenous variables that affect on other variables, and 'standard infection control ($y_1$)','Organization equipment management handwashing ($y_2$)', 'environmental infection control ($y_3$), 'personal protective equipment ($y_4$)', 'waste and laundry management ($y_5$)' are endogenous variables that are infulenced by others. The standardized metrics are more needed than anything else when examining on infection control. This study attempts to develop proper dental infection control metrics adequately adjusted for domestic circumstances, and therefore to contribute to effective systematic management and decision-making in infection control.

• Journal of the Korean Society of School Health
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• v.2 no.1
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• pp.91-107
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• 1989

This study was designed to evaluate current level of school health practice in Chonbuk province and to analyze the relationship between school health practice and variables. All the subjects in this study were 140 schools themselves in Chonbuk province. Survey data was collected through the interviewed checklists from the widly accepted school health responsibilities of administration and practice and the direct observation by the interviewer. It was conducted from 1st of Nov. to 17 th of Dec, 1988. The major findings of this study are as follows: A. Level of school health practice was relatively low in score (Mean=64.5). $\cdot$ Healthful School Living -76.14 $\cdot$ School Health Service -71.29 $\cdot$ School Health Instruction -47.98 B. Strengths and Weakness field in School Health Practice. 1. Healthful School Living: Strengths: Waste disposal, Seating, Playground. Weakness: School site, Safety control. 2. School Health Service : Strenths : Health Appraisal, Follow up and Counseling. Weakness: Dental Health, Prevention and Control of Communicable Disease, Facilities and Equipment of Health Clinic. 3. School Health Instruction : Strength : None, Weakness : Program Organization, Curriculum Planning and Evaluation, Curriculum Content, Instructional Aids. C. Significance between degree of School Health Practice and Variables. 1. Healthful School Living : (1) Toilet : Area (p<0.001), No.of Class (p<0.001), School Nurse (p<0.05) (2) Water Supply : School Nurse (p<0.05) (3) Safety Control : School Nurse (p<0.05) 2. School Health Service : (1) Health Appraisal : School Nurse (p<0.05) (2) Follow up and Counseling : School Nurse (p<0.001) (3) Dental Health : Area (p<0.05), Level of School (p<0.05) (4) Prevention and Control of Communicable Disease : Level of School (p<0.001), School Nurse (p<0.05) (5) Emergency Care : Area (p<0.001), No. of Class (p<0.001), School Nurse(p<0.001) (6) Facilities and Equipment of Clinic : Level of School (p<0.001), No.of Class (p<0.001), School Nurse (p<0.001) 3. School Health Instruction: (1) Program Organization : No. of Class (p<0.05), School Nurse (p<0.001) (2) Curriculum Planning land Evaluation : School Nurse (p<0.001) (3) Instructional Aids : Level of School (p<0.001), School Nurse (p<0.05) Recommendation for the Improvement of School Health Practice are as follows : A. There should be further study to strengthen the school health practice, especially in the field of school health instruction. B. It is strictly required to employ and utilize school nurse at each school level not only for the school health service but also for the school health in struction. C. There should be much considerations about adequate size and easily accessible distance in school site.