• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.361-364
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• 2009

KEPRI has studied planar type SOFC stacks using anode-supported single cells and kW class co-generation systems for residential power generation. A 1kW class SOFC system consisted of a hot box part, a cold BOP part and a water reservoir. A hot box part contains a SOFC stack made up of 48 cells with $10{\times}10cm^2$ area and ferritic stainless steel interconnectors, a fuel reformer, a catalytic combustor and heat exchangers. Thermal management and insulation system were especially designed for self-sustainable operation. A cold BOP part was composed of blowers, pumps, a water trap and system control units. When a 1kW class SOFC system was operated at $750^{\circ}C$ with hydrogen, the stack power was 1.2kW at 30 A and 1.6kW at 50A. Turning off an electric furnace, the SOFC system was operated using hydrogen and city gas without any external heat source. Under self-sustainable operation conditions, the stack power was about 1.3kW with hydrogen and 1.2kW with city gas respectively. The system also recuperated heat of about 1.1kW by making hot water. Recently KEPRI developed stacks using $15{\times}15cm^2$ cells and tested them. KEPRI will develop a 5 kW class CHP system using $15{\times}15cm^2$ stacks by 2010.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.5
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• pp.384-389
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• 2009

KEPRI (Korea Electric Power Research Institute) has studied planar type solid oxide fuel cell (SOFC) stacks using anode-supported cells and kW class co-generation systems for residential power generation. In this work, a 1 kW SOFC system consisted of a hot box part, a cold BOP (balance of plant) part, and a hot water reservoir. The hot box part contained a SOFC stack made up of 48 cells, a fuel reformer, a catalytic combustor, and heat exchangers. Thermal management and insulation system were especially designed for self-sustainable operation in that system. A cold BOP part was composed of blowers, pumps, a water trap, and system control units. When the 1 kW SOFC stack was tested using hydrogen at $750^{\circ}C$, the stack power was about $1.2\;kW_e$ at 30 A and $1.6\;kW_e$ at 50 A. Turning off an electric furnace, the SOFC system was operated using hydrogen and city gas without any external heat source. Under self-sustainable operation conditions, the stack power was about $1.3\;kW_e$ with hydrogen and $1.2\;kW_e$ with city gas respectively. The system also recuperated heat of about $1.1\;kW_{th}$ by making hot water.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.2
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• pp.181-189
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• 2018

Polymer electrolyte membrane fuel cell (PEMFC) system receives great attention as a promising power device for automotive applications. For the wide commercialization, the efficiency and performance of automotive PEMFC system should be further improved in terms of total system (stack and balance of plant [BOP]). Air supply module, which is a major part of the BOP, greatly affects the efficiency of automotive PEMFC system. In this paper, a systematic study on the low-pressure automotive PEMFC system was made in an attempt to enhance the net system efficiency. This study mainly presents an investigation of the effect of blower configuration (1-blower and 2-blower) on the net system efficiency of automotive PEMFC system. For this purpose, the effect of operating pressure and cathode stoichiometry on the system efficiency was investigated with stack temperature under the fixed net system power condition. Results indicate that 1-blower system is better in system efficiency over 2-blower system under an air stoichiometry of 2. However, 2-blower system is better in system efficiency under an air stoichiometry of 3. The simulation results show that the optimum operating strategy needs to be established for various blower system configurations considering blower performance maps.

• Journal of Periodontal and Implant Science
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• v.24 no.3
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• pp.529-540
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• 1994

Rapidly progressive periodontitis is known to be usually associated with systemic problems and improved with antibiotic therapy. Recent experiments in which bioresorbable polycaprolactone was polymerized with minocycline has shown that the system released effective antibiotic concentration during the 7 days' period. This clinical trial was to compare the efficacy of a minocycline film(poly-caprolactone+polyglycol+10% minocycline) insertion plus supragingival scaling(MS) or subgingival scaling & root planing(MSRP) with the scaling(S) or subgingival scaling & root planing alone(SRP), at improving the periodontal condition in RPP. Fifteen patients were examined for plaque accumulation, gingival inflammation, probing depth and attachment loss at baseline, then 1, 2, 4 and 8 weeks after 4 treatment regimens were randomly undergone in 4 comparable sites(PD>5mm, LA>3mm) in each subject. Results revealed statistically significant treatement effect with a reduction in a probing depth in SRP(2.0mm), MS(1.8mm), and MSRP(2.1mm). There was no significant reduction in the supragingival scaling alone group(0.6mm). Similarly, attachment levels were significantly improved in the SRP(1.5mm), MS(2.0mm) and MSRP(2.0mm) groups. Net % BOP reduction at 8 week compared to baseline was 6.7% (S), 26.7% (MS), 26.7% (SRP), and 33.3% (MSRP). MSRP produced the greatest improvement in BOP at 8 week. This data suggests that a subgingival minocycline delivery system as a adjunct to scaling alone or scaling & root planing may produce significant clinical benefits over scaling alone in rapidly progressive periodontitis patients.

• Journal of Periodontal and Implant Science
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• v.50 no.2
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• pp.83-96
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• 2020

Purpose: The present study aimed to evaluate the clinical benefit of additional toothbrushing accompanying non-surgical periodontal treatment on oral and general health in patients with type 2 diabetes mellitus (T2DM). Methods: We conducted a doubled-blind randomized controlled trial in 60 T2DM patients between June 2013 and June 2014. The patients were randomly assigned to the scaling and root planing (SRP) group; the scaling and root planing with additional toothbrushing (SRPAT) group, in which additional toothbrushing was performed by toothpick methods; or the control group. Microbiological and oral examinations were performed for up to 12 weeks following treatment. Non-surgical treatment was conducted in the experimental groups. The SRP group received scaling and root planing and the SRPAT group received additional toothbrushing with the Watanabe method once a week from the first visit through the fifth visit. The primary outcomes were changes in haemoglobin A1c (or glycated haemoglobin; HbA1c) levels, serum endotoxin levels, and interleukin-1 beta levels. Periodontal health status was measured by periodontal pocket depth, the calculus index, and bleeding on probing (BOP). Results: Both the SRP and SRPAT groups showed improvements in periodontal health and HbA1c, but the SRPAT group showed significantly less BOP than the SRP group. Furthermore, only the SRPAT group showed a statistically significant decrease in serum endotoxin levels. Conclusions: Non-surgical periodontal treatment was effective in improving HbA1c and serum endotoxin levels in T2DM patients. Furthermore, non-surgical treatment with additional tooth brushing had a more favourable effect on gingival bleeding management. Trial RegistrationClinical Research Information Service Identifier: KCT000416.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.2
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• pp.281-286
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• 2013

As the product lifecycle is getting shorter and various models should be released to respond to the needs of customers and markets, automation-based flexible production line has been recognized as the core competitiveness. According to these trends, system vendors supply cell-level systems such as FMC(Flexible Manufacturing Cell) that is integration of core functions of FMS(Flexible Manufacturing System) and RMC(Reconfigurable Manufacturing Cell) that can easily extend components of FMC. In the cell-based environment, flexible management for shop floor composed of existing job shop, FMCs and RMCs from various system vendors has emerged as an important issue. However, there could be some problems on integrated operation between heterogeneous cells to use vendor-specific cell controllers and on seamless information flow with high level systems such as ERP(Enterprise Resource Planning). In this context, this paper proposes process management systems supporting integrated shop operation of heterogeneous multi-cell based flexible manufacturing environment: First of all, (1) Integrated Shop Operation System to apply the process management system is introduced, and (2) Multi-Layer BOP(Bill-Of-Process) model, a backbone of the process management system, is derived with its data structure. Finally, application of the proposed model is illustrated through system implementation results.

• Journal of Periodontal and Implant Science
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• v.48 no.5
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• pp.326-333
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• 2018

Purpose: The present study investigated the outcomes of a newly-developed, simple, and practical nonsurgical treatment modality suitable for most forms of intrabony defects around failing dental implants using intrasulcular delivery of chlorhexidine solution and minocycline hydrochloride (HCl). Methods: Forty-five dental implants in 20 patients diagnosed with peri-implantitis were included. At baseline and the study endpoint, the probing pocket depth (PPD), clinical attachment level (CAL), and the presence of bleeding on probing (BOP) at 6 sites around each implant were recorded. The radiographic osseous defect morphology at the mesial or distal proximal aspect of each implant was classified as 1) narrow or wide and 2) shallow or deep. For a comparative analysis of bone changes according to the defect morphology, the distance from the implant shoulder to the most coronal bone-to-implant contact point (DIB) at the mesial and distal aspects of each implant was measured at baseline and the endpoint. Patients were scheduled to visit the clinic every 2-4 weeks for intrasulcular irrigation of chlorhexidine and delivery of minocycline HCl. Results: We observed statistically significant decreases in PPD, CAL, and BOP after treatment. At the endpoint, bone levels increased in all defects, regardless of the osseous morphology of the intrabony defect. The mean DIB change in deep defects was significantly greater than that in shallow defects. Although the mean bone gain in narrow defects was greater than in wide defects, the difference was not statistically significant. Conclusions: We propose that significant and sustainable improvements in both clinical and radiographic parameters can be expected when intrabony defects around dental implants are managed through a simple nonsurgical approach involving combined intrasulcular chlorhexidine irrigation and local delivery of minocycline HCl.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.37-43
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• 2008

The durability test of turbo-blower for PEM fuel cell is very important process of BOP development. It is a major barrier to the commercialization of these systems for stationary and transportation power applications. Commercial viability depends on improving the durability of the air supply system to increase the reliability and to reduce the lifetime cost. In this study, turbo-blower supported by oil-free bearing is introduced as the air supply system used by 80kW proton exchange membrane fuel systems. The turbo-blower is a turbo machine which operates at high speed, so air foil bearings suit their purpose as bearing elements. The impeller of blower was adopted mixed type of centrifugal and axial. So, it has several advantages for variable operating condition. The turbo-blower test results show maximum parasitic power levels below 1.67kW with the 30,000 rpm rotating speed, the flow rate of air has maximum 163SCFM(@PR1.1). For proper application of FCV, these have to durability test. This paper describes the experiment for confirming endurance and stability of the turbo-blower for 500 hours.

• Journal of Periodontal and Implant Science
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• v.31 no.4
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• pp.765-775
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• 2001

The aim of the study was to investigate the effect of surgical therapy combined with the usage of metronidazole gel in the treatment of juvenile periodontitis by comparing clinical indices of flap operation along with application of metronidazole gel and flap operation only. Comparing clinical indices of the baseline, 3 months after surgery, 6 months after surgery statistically, the results are as follows; 1. Bleeding on probing (BOP) was decreased significantly both in the experimental group and the control group at 3 months after surgery (p<0.05). BOP increased 0.9% in the control group 6 months after surgery, while in the experimental group, decreased 4.7% (p>0.05). However, there was no statistically significant difference in these groups (p>0.05). 2. Pocket probing depth (PPD) was decreased significantly both in the experimental group and the control group at 3 months after surgery (p<0.05). PPD increased 0.lmm in the control group 6 months after surgery, while in the experimental group, no increase of the depth could be observed (p>0.05). However, there was no statistically significant and difference in these groups (p>0.05). 3. Loss of attachment level(LOA) was decreased significantly both in the experimental group and the control group at 3 months after surgery (p<0.05). LOA increased 0.2mm in the control group 6 months after surgery, while in the experimental group, increased 0.3mm However, there was no statistically significant difference in these groups (p>0.05). In conclusion, flap operation was effective on the treatment of juvenile periodontitis. However, combined therapy of metronidazole gel could not give rise to any significant adjunctive effect on the treatment outcome.

• Journal of the Korea Society for Simulation
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• v.20 no.2
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• pp.11-17
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• 2011

The purpose of this study is 3 dimensional modeling of lower part of drilling system in offshore rig and simulation of drilling process. Recently, shipbuilding companies have been focusing on offshore rigs due to their high added-value and the reduced demand of new shipbuilding. In most cases, however, the basic design, installation and management of offshore rig are carried out by foreign companies. Therefore, it is difficult to obtain the knowledge and information of drilling system. In this study drilling devices, BOP(Blowout Preventor) and cementing job and mud circulation related components are included as the main components of offshore rig. The structure and function of them were analyzed from a viewpoint of object-oriented technique. On the basis of this analysis they were modeled in the 3 dimensional structure with 3D software tool such as CATIA and 3DVIA Composer. The drilling process was simulated according to the scenario of drilling operation. This simulation system can be effectively used for an educational tool for students and engineers in ocean plant industries.