• Journal of The Korea Institute of Healthcare Architecture
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• v.10 no.2
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• pp.51-58
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• 2004

In this paper, the problem of subway platform is analyzed and the alternative as a screen door is suggested. This paper aims to improve the facility law in subway platform. Because facility law related to platform is absent, the study scope is limited to detail design that is matched to rules. Field survey is performed to 300 persons that are 150 men and 150 women in Shingil station in which the screen door is established. Also the persons are used the screen door at least 3 times. It makes the field survey credible. The study is proceeded as follows ; First, the law related to platform, the problem of platform, and the plan and status of screen door are analyzed. Second, the definition, and composition of screen door are examined. Then, kinds of screen door is analyzed and the advantage and disadvantage of each kind of screen door are compared. Third, the necessity of establishing the screen door is examined through field survey and error range of stop position is investigated. Through this flow, final results is abstracted. Direction of facility related to subway platform, applied objective and range are suggested based on this study. This study focuses the stability of platform, pleasantness, and energy saving and suggests facility improvement direction through introducing the screen door and further study.

• International Journal of Computer Science & Network Security
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• v.21 no.3
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• pp.212-218
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• 2021

Low-power and Lossy Networks (LLNs) have become the common network infrastructure for a wide scope of Internet of Things (IoT) applications. For efficient routing in LLNs, IETF provides a standard solution, namely the IPv6 Routing Protocol for LLNs (RPL). It enables effective interconnectivity with IP networks and flexibly can meet the different application requirements of IoT deployments. However, it still suffers from different open issues, particularly in large-scale setups. These include the node unreachability problem which leads to increasing routing losses at RPL sink nodes. It is a result of the event of memory overflow at LLNs devices due to their limited hardware capabilities. Although this can be alleviated by the establishment of multi-sink topologies, RPL still lacks the support for effective load balancing among multiple sinks. In this paper, we address the need for an efficient multi-sink load balancing solution to enhance the performance of PRL in large-scale scenarios and alleviate the node unreachability problem. We propose a new RPL objective function, Multi-Sink Load Balancing Objective Function (MSLBOF), and introduce the Memory Utilization metrics. MSLBOF enables each RPL node to perform optimal sink selection in a way that insure better memory utilization and effective load balancing. Evaluation results demonstrate the efficiency of MSLBOF in decreasing packet loss and enhancing network stability, compared to MRHOF in standard RPL.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.6
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• pp.331-337
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• 2023

Due to the aging of a building, 38.8% (about 2.82 million buildings) of the total buildings are old for more than 30 years after completion and are located in a blind spot for an inspection, except for buildings subject to regular legal inspection (about 3%). Such existing buildings require users to self-inspect themselves and make efforts to take preemptive risks. The scope of this study was defined as the general public's visual self-inspection of buildings and was limited to structural members that affect the structural stability of old buildings. This study categorized possible damage to reinforced concrete to check the structural safety of buildings and proposed a checklist to prevent the damage. A damage assessment methodology was presented during the inspection, and a self-inspection scenario was tested through a chatbot connection. It is believed that it can increase the accessibility and convenience of non-experts and induce equalized results when performing inspections, according to the chatbot guide.

• The Journal of the Korean dental association
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• v.51 no.12
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• pp.650-657
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• 2013

The aim of this study was to achieve healing of Peri-implantitis defects and hard tissue augmentation using a bovine-derived bone mineral on the defect site. Two patients were treated with the surgical approach. With a full muco-periosteal flap elevation, the implant surfaces were exposed and granulation tissue removed around the implant and between the threads. Each surface of the contaminated implant was prepared with the air-abrasive device(PerioFlow$^{(R)}$) for decontamination. Bovine-derived bone mineral(Bio-Oss collagen$^{(R)}$) was then used to fill the defects and muco-periosteal flaps sutured to achieve transmucosal healing. Radiographs and clinical photographs were taken before and after 6 months of healing and an estimate of bone fill was assessed. Within the limits of the present case report, a surgical approach in treatment of peri-implantitis defects using a collagen form of bovine bone mineral was visited. Although limited, the two cases showed the stability and biocompatibility of a bovine-derived bone mineral and effectiveness of air-abrasive device(PerioFlow$^{(R)}$) as a decontamination method.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.7
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• pp.401-406
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• 2003

Electric power industries in several countries are currently undergoing major changes, mainly represented by the privatizations of the power plants and distribution systems. Reliable operations of the power plants directly contribute to the revenue increases of the generation companies in such competitive environments. Strategic optimizations should be performed between the levels of the reliabilities to be maintained and the various preventive maintenance costs, which require the accurate estimations of the power plant reliabilities. However, accurate estimations of the power plant reliabilities are often limited by the lack of accurate power plant failure data. A power plant is not supposed to be failed that often. And if it fails, its impact upon the power system stability is quite substantial in most cases, setting aside the significant revenue losses and lowered company images. Reliability assessment is also important for Independent System Operators(ISO) or Market Operators to properly assess the level of needed compensations for the installed capacity based on the availability of the generation plants. In this paper, we present a power plant reliability estimation technique that can be applied when the failure data is insufficient. Median rank and Weibull distribution are used to accommodate such insufficiency. The Median rank is utilized to derive the cumulative failure probability for each ordered failure. The Weibull distribution is used because of its flexibility of accommodating several different distribution types based on the shape parameter values. The proposed method is applied to small size failure data and its application potential is demonstrated.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1547-1558
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• 2015

A predictive functional control (PFC) scheme for permanent magnet synchronous motor (PMSM) servo systems is proposed in this paper. The PFC-based method is first introduced in the control design of speed loop. Since the accuracy of the PFC model is influenced by external disturbances and speed detection quantization errors of the low distinguishability optical encoder in servo systems, it is noted that the standard PFC method does not achieve satisfactory results in the presence of strong disturbances. This paper adopted the Kalman filter to observe the load torque, the rotor position and the rotor angular velocity under the condition of a limited precision encoder. The observations are then fed back into PFC model to rebuild it when considering the influence of perturbation. Therefore, an improved PFC method, called the PFC+Kalman filter method, is presented, and a high performance PMSM servo system was achieved. The validity of the proposed controller was tested via experiments. Excellent results were obtained with respect to the speed trajectory tracking, stability, and disturbance rejection.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.1
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• pp.61-72
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• 2014

Study on effluent organic matter (EfOM) characteristic and removal efficiency is required, because EfOM is important in regard to the stability of effluents reuse, quality issues of artificial recharge and water conservation of aqueous system. UV technology is widely used in wastewater treatment. Many reports have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on EfOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics. The high intensity of pulsed UV would mineralize EfOM itself as well as change the characteristics of EfOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of EfOM. The objective of this study is to investigate the effect on EfOM, chlorine residual, and chlorinated DBPs formation with low pressure and pulsed UV treatment. The removal of organic matter through low pressure UV treatment is insignificant effect. Pulsed UV treatment effectively removes/transforms EfOM. As a result, the chlorine consumption is changed and chlorine DBPs formation is decreased. However, excessive UV treatment caused problems of increasing chlorine consumption and generating unknown by-products.

• Progress in Superconductivity and Cryogenics
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• v.6 no.4
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• pp.17-21
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• 2004

The butt joint was verified to satisfy the thermal stability of the ITER magnet system through the ITER CS model coil test. Since the contact area in the butt joint is limited to the cross section of the cable, it is necessary to analyze and control the joining parameters precisely for improving the DC resistance. It is difficult to simulate the cables, which are composed of a lot of strands, as three-dimensional models using the commercial code. The random numbers were used to simulate many kinds of contact patterns of the strands on the bonding surface for calculating the bonding area and the DC resistance of the butt joint. The calculated DC resistance decreases with an increase of cable filling factor in terminal. The calculated DC resistance of a 0.9 cable filling factor is about 0.48 n-Ohm, which is about one-tenth of that in the CS model coil test when not considering the electrical contact resistance. From this difference, the electrical contact resistance between the strands and copper sheet was calculated.

• Applied Microscopy
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• v.43 no.4
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• pp.173-176
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• 2013

The oxidation behavior of the crystallized $Al_{87}Ni_3Y_{10}$ alloy has been investigated with an aim to compare with that of the amorphous $Al_{87}Ni_3Y_{10}$ alloy. The oxidation at 873 K occurs as follows: (1) growth of an amorphous aluminum-yttrium oxide layer (~10 nm) after heating up to 873 K; and (2) formation of $YAlO_3$ crystalline oxide (~220 nm) after annealing for 30 hours at 873 K. Such an overall oxidation step indicates that the oxidation behavior in the crystallized $Al_{87}Ni_3Y_{10}$ alloy occurs in the same way as in the amorphous $Al_{87}Ni_3Y_{10}$ alloy. The simultaneous presence of aluminum and yttrium in the oxide layer significantly enhances the thermal stability of the amorphous structure in the oxide phase. Since the structure of aluminum-yttrium oxide is dense due to the large difference in ionic radius between aluminum and yttrium ions, the diffusion of oxygen ion through the amorphous oxide layer is limited thus stabilizing the amorphous structure of the oxide phase.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.33.1-33.1
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• 2018

pH is expressed mathematically as $pH=-{\log}[H^+]$, is a measure of the hydrogen ion concentration, [$H^+$] to specify the acidity or basicity of an aqueous solution. The pH scale usually ranges from 0 to 14. Every aqueous solution can be measured to determine its pH value. The pH values below 7.0 express the acidity, above 7.0 are alkalinity and pH 7.0 is a neutral solution. The solution pH can be determined by indicator or by measurement using pH sensor, which measuring the voltage generated between a glass electrode and a reference electrode according to the Nernst Equation. The pH value of solutions depends on the temperature and the activity of contained ions. In nickel electroless plating process, the controlled pH value in some limited ranges are extremely important to achieve optimal deposition rate, phosphorus content as well as solution stability. Basically, nickel electroless plating solution contains of $Ni^{2+}ions$, reducing agent, buffer and complexing agents. The plating processes are normally carried out at $82-92^{\circ}C$. However, the change of its pH values with temperatures does not follow any rule. Thus, the purpose of study is to understand the relationship between pH and temperature of some based solutions and electroless nickel plating solutions. The change of pH with changing temperatures is explained by view of the thermal dynamic and the practical measurements.