• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.253.1-253.1
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• 2014

Plasma technology has been widely used for decontamination, differentiation, and disease treatment. Recently, studies show that plasma has effects on increasing seed germination and plant growth. In spite of increasing number of studies about plasma effects, the interaction between plasma and plants has been rarely informed. In this study, we have analyzed the effects of nonthermal atmospheric pressure plasma on seed germination and growth of coriander (Coriandum sativum), a medicinal plant. We used to Ar, air, and N2 plasma on seed as feeding gases. Plasma was discharged at 0.62 kV, 200 mA, 9.2 W. Seed germination was increased over time when treated with N2 based DBD plasma for exposure times of 30 seconds and 1 minute, everyday. After 7 days, about 80~100% of seeds were germinated in the treatment with N2 based DBD plasma, compared to control (about 40%, only gas treated seeds). In order to elucidate the mechanism of increased germination, we have analyzed characteristics of changes in plant hormones and seed surface structure by SEM.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.650-654
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• 2003

A major problem of nuclear energy is the production of radioactive wastes. Needs for more environmentally favorable method to decontaminate radioactive contaminants make the use of liqui $d^ercritical $CO_2$ as a solvent medium. In removing radioactive metallic contaminants under $CO_2$ solvent, two methods - use of chelating ligands and that of water in $CO_2$ emulsion-are possible. In the chelating ligand method, a combination of ligands that can make synergistic effects seems important. We discuss about the properties of microemulsion formed by F-AOT and that by non-ionic surfactant. By adding acid in water core, decontamination of metallic parts, soils were possible. The rate of metal surface dissolution to the microemulsion solution was measured by QCM. The possibility of recovering the surfactants after use is also mentioned.ed.

• Restorative Dentistry and Endodontics
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• v.31 no.2
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• pp.133-139
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• 2006

The purposes of this study were firstly to identify the microbial species on gutta-percha (GP) cones exposed at outpatient clinics using polymerase chain reaction, and secondly to evaluate the rapid sterilization effect of two chemical disinfectants at chair side. It also evaluated the alteration of surface texture of GP cones after 5-min soaking into two chemical disinfectants. A total of 100 GP cones from two endodontic departments were randomly selected for microbial detection using PCR assay with universal primer. After inoculation on the sterilized GP cones with the same microorganism identified by PCR assay, they were soaked in two chemical disinfectants: 5% NaOCl and 2% chlorhexidine for 1, 3, 5, and 10 minutes. The sterilization effect was evaluated by turbidity and subculture. The change of surface textures using a scanning electron microscope was also examined after 5 min-soaking in two chemical disinfectants. Results showed that four bacterial species were detected in 17 GP cones, and all the species belonged to the genus Staphylococcus. Two chemical disinfectants were effective in sterilization with just 1 minute soaking. On the SEM picture of NaOCl-soaked GP cone, a cluster of cuboidal crystals was seen on the cone surface. Present data demonstrate that two chemical disinfectants are useful for rapid sterilization of GP cone just before obturation at chair side, while CHX-soaked GP cone has cleaner surface without crystal precipitation than that of NaOCl-treated cone.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.1
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• pp.43-53
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• 2007

The purpose of this experimental study was to examine the effect of the decontamination of carbon dioxide ($CO_2$) laser in treatment of ligature-induced peri-implantitis in dogs. A total 24 implants with a sandblasted with large-grit and acid-etched (SLA) surface were inserted in six mongrel dogs. After a 3-month healing period, experimental peri-implantitis characterized by a bone loss of about 3mm was established by inducing with wires. And then wires were removed and plaque control was implemented. Surgical treatment involving flap procedure + debridement of implants surface with chlorhexidine and saline (group 1), flap procedure + GBR with absorbable collagen membrane (Bio-Gide) and mineralized bone graft (Bio-Oss) (group 2), and flap procedure + $CO_2$ laser application + GBR (group 3) was performed. The animals were killed 8 weeks and 16 weeks after treatment, respectively. A histomorphometric analysis confirmed statistically considerable new bone formation within the limit of the 5 most coronal threads in group 3 compared with group 1 at 16 weeks (P<0.05). And intragroup analysis showed considerable increase of new bone formation in group 3 at 16 weeks compared with 8 weeks (P<0.05). The present study demonstrates considerable new bone formation after treatment of experimental peri-implantitis with flap procedure, $CO_2$ laser application and GBR.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.135-135
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• 2017

제염기술은 원자력발전소의 순환계통장치 및 기기류의 방사성 오염물질을 제거하는 기술이다. 현재 국내 원전의 설계 수명 및 유지보수 시기가 도래함에 따라, 작업 전 작업자의 방사선 피사량을 극소화하기 위한 제염 기술이 주목을 받고 있다. 제염 방법에는 크게 기계적 제염과 화학약품을 사용하는 화학제염이 있다. 그 중 화학제염은 복잡한 구조의 제염 대상물에 대한 큰 효과 및 간단한 공정 때문에 주로 사용되고 있다. 제염 시 방사성 산화물과 오염성분을 제거하기 위해 강산 또는 강알칼리의 화학용액이 사용된다. 강한 화학약품을 사용함으로써 큰 제염효과를 얻을 수 있는 반면, 금속 재료의 부식에 대한 구동력도 커지게 된다. 금속 재료의 경우, 강한 부식성 환경에서 공식(pitting corrosion) 및 입계부식(intergranular corrosion)형태의 손상이 크게 발생하기 때문에, 제염공정 시 사용되는 화학용액에 대한 재료의 건전성 검증이 반드시 필요하다. 본 연구에서는 원전기기용 재료인 니켈합금강 Inconel600의 화학제염 시 시험공정 3가지에 대한 부식손상 특성을 규명하였다. 산화공정은 $HMnO_4$ 실험용액을 공통으로 사용하였으며, 산화공정 종료 후 환원공정은 각 시험공정에 따라 환원공정 1은 2000ppm $H_2C_2O_4$, 환원공정 2는 1500ppm $H_2C_2O_4$ + 500ppm $H_8C_6O_7$, 그리고 환원공정 3은 3000ppm $H_2C_2O_4$ 실험용액을 각각 투입하여 수행하였다. 산화, 환원공정을 1Cycle로 하여 온도 $75^{\circ}C$로 유지된 용액에 각 2시간씩 침적하였다. 각 시험공정 별로 총 5Cycle을 실시하였다. 각 시험공정 Cycle종료 후 시험편을 취외하여 무게감량측정, SEM(Scanning electron microscope)분석, 3D현미경분석 그리고 타펠분극 실험을 실시하였다. 각 분석결과를 토대로 하여, 니켈합금 Inconel600에 대한 화학제염 시 시험공정에 따른 부식특성을 규명하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.136-136
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• 2017

화학제염 기술은 산화제, 환원제, 금속이온, 무기산등이 혼합되어 있는 화학용액을 사용하여 원전기기 계통 내부에 생성된 고방사능 준위의 산화막과 오염물질을 제거하는 기술이다. 원전의 해체 및 유지보수에 있어 방사능 피복저감을 위한 필수적인 기술이다. 현재 원전 해체 산업은 잠재성이 높은 고부가가치 창출 산업으로 주목을 받고 있다. 원전 보유국의 경우, 기존 상용 제염기술과는 차별성 있는 제염기술을 확보하고자 노력하고 있다. 기존의 공정과 비교하여 공정비용 및 시간을 감소시킬 수 있어야 할 뿐만 아니라, 화학용액에 의한 원전 계통 금속 부품의 부식 및 손상을 최소화해야 한다. 금속 부품이 화학약품에 의한 부식손상을 받는다면 금속 부품의 수명 및 재활용 가치가 감소하기 때문에, 화학제염 기술 적용에 있어 용액에 대한 재료의 건전성 평가가 사전에 필히 이루어져야 한다. 본 연구에서는 원전 냉각재 펌프용 재료로 주로 사용되는 Stainless 304강을 시험편으로 선정하여, 화학제염 시험공정 3가지에 대한 부식손상 특성을 규명하였다. 산화공정은 과망간산($HMnO_4$) 용액을 공통으로 사용하였으며, 산화공정 종료 후 환원공정은 각 시험공정에 따라 시험공정 1은 옥살산($H_2C_2O_4$) 2000ppm, 시험공정 2는 옥살산($H_2C_2O_4$)1500ppm + 시트르산($H_8C_6O_7$)500ppm, 그리고 시험공정 3은 옥살산($H_2C_2O_4$) 3000ppm 용액을 각각 투입하여 수행하였다. 산화, 환원공정을 1Cycle로 하여, 각 시험공정 별로 총 5Cycle을 실시하였다. 각 시험공정 Cycle종료 후 시험편을 취외하여 무게감량측정, SEM(Scanning electron microscope) 분석, 3D현미경분석 그리고 타펠분극 실험을 실시하였다. 각 분석결과를 토대로 하여, Stainless 304강에 대한 화학제염 시 모델별 시험공정에 따른 부식특성을 규명하였다.

• Nuclear Engineering and Technology
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• v.2 no.2
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• pp.97-106
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• 1970

Radiation accidents which occured in the A.E.R.I. during last ten years are described (table 1). It seemed to the authors that some of these accidents were considered to be hazardous to man body and associated installations. This report deals with the following four major accidents involving body contamination incidents that our health physicists have been experienced. 1. Over-exposures (up to 130 rem) to the total body due to the mismanipulation in the Cobalt-60 gamma irradiation facility. 2. Floor surface contamination (up to 13 mrad/hr) and its spread out due to the mishandling of radioiodine contained in the bottle. 3. Body surface contamination and 0.36 uCi radioactivity accumulated in the thyroid gland of a worker due to the inhalation of gaseous iodine-131. 4. A void capsule due to the leakage out of the radium therapeutic source (3mg\ulcorner) These accidents were treated by definitely prompt action to protect the workers and associated installations from any radiation hazards and every possible efforts were made to confine the spread of radioactive contamination as small area as possible by means of elaborate decontamination work and monitoring.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.19 no.1
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• pp.11-15
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• 2013

In order to find a sanitary logistic way to handle library books, papers and environmental sources contacting the books were tested in their microbial contamination load and methods to decontaminate the books were investigated. Generally bacterial load of inner book pages was very low, but increased when contaminated with liquid such as saliva. In contrast, their lateral ends showed much higher bacterial contamination presumably due to dry dust contamination on there. As operations to improve the sanitary book conditions, turbulent air blow was found to be workable for reducing dry dusty contamination and 280 nm ultra-violet (UV) light emitting diode (LED) was so for decontaminating wet surface contamination. Microbial inactivation by the UV LED could be realized with irradiation for more than 5 minutes at 2 cm distance. Air blow of 5.5 m/s for 0.5~1 minute could reduce the dusty contamination on a model book surface.

• Journal of Periodontal and Implant Science
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• v.51 no.4
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• pp.276-284
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• 2021

Purpose: The aim of this randomized clinical trial was to assess whether chemical cleansing using a sulfonic/sulfuric acid gel solution (HBX) as an adjunct to scaling and root planing (SRP) resulted in a decrease in residual plaque and calculus in deep periodontal pockets compared to SRP alone. Methods: Fifty-six patients with 56 hopeless posterior teeth, scheduled for extraction due to severe periodontitis, were enrolled in this study. Each tooth was randomly assigned to 1 of the 2 experimental procedures. The test teeth were subjected to the irrigation of the subgingival area with HBX for 2 minutes, followed by SRP with hand and ultrasonic instruments for 14 minutes, and then extracted. The control teeth received only mechanical instrumentation before extraction. Residual biofilm was evaluated on photographs and measured as total area and percentage of root surface covered by remaining plaque (RP) or calculus (RC) after treatment. Results: The initial pocket depth (PD) and total subgingival root surface area were similar between the 2 treatment groups. After treatment, the total subgingival root area covered by RP and RC was statistically significantly larger (P<0.001) in the control group than in the test group. The test teeth showed a lower percentage of RP, but a higher percentage of RC than the control teeth (both P<0.001). Complete calculus removal was achieved in 42% of the control teeth surfaces and in 25% of the test teeth surfaces for a PD of 4 mm. Conclusions: The additional chemical cleansing with HBX resulted in a statistically significant improvement in bacterial plaque removal during SRP of deep pockets, but it was not effective in reducing calculus deposits.

• Journal of Korean Biological Nursing Science
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• v.23 no.4
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• pp.339-346
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• 2021

Purpose: To determine the extent of environmental contamination and the effect of disinfection around patients with carbapenem-resistant Enterobacteriaceae (CRE) using adenosine triphosphate (ATP) measurements and microbial culture tests. Methods: The subjects of this study were 10 patients hospitalized in a single room due to CRE from April 13 to 21, 2021. One hundred and sixty samples were collected using cotton swabs from the patients' environment including the surface and drain of sinks and toilet seats before and after disinfection of the room after discharge. Twenty-one samples were collected from the nurses' personal digital assistants (PDAs), keyboards, and computer mice before disinfection. The relative light units (RLUs) and CRE colony-forming units (CFU) of 181 samples were measured using ATP test equipment and chrome agar plates, respectively. Results: The highest RLUs were measured at the sink drains before and after disinfection. Four CRE samples from the sink drains (2), sink surface (1), and toilet bowl (1) before disinfection were cultured. Based on the failure criteria (≥ 250 RLU/cm² and ≥ 1 CFU/100 cm²), 90 % and 50 % of the samples from the drain exceeded the failure criteria before and after disinfection, respectively. In the culture tests, CRE was not detected after disinfection. Conclusion: According to the RLU and CFU measurements of drain samples, disinfection was not effective. Thus, improvements in the disinfection methods of drains, as well as more efficient and systematic environmental decontamination and disinfection evaluation tools, are needed to accurately evaluate the effectiveness of disinfection in various places.