• Journal of Korean Society of Water and Wastewater
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• v.23 no.3
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• pp.321-329
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• 2009

I/I(Infiltration/Inflow) characteristics should be studied to achieve I/I reduction which is a main object of sewer rehabilitation. However, The scientific and practical studies which are based on actual survey within the country are not thorough going enough. The earlier studies were limited because of a short research period and specific region. Thus, In this study, a formula is deduced by intensive correlation analysis between defective number and I/I volume in sewer pipe. It can be used as preliminary data when the project established for cost-effective pipe rehabilitation. The study shows that the researched region have a faulty point at every 9.3m on average and prove correlation between defective number and I/I volume in sewer pipes. Thus, this study can improve the investigation system and estimate the volume of the pipe rehabilitation, when site investigations for rehabilitation have been conducted.

• Journal of IKEEE
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• v.22 no.3
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• pp.759-766
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• 2018

This paper presents a high-speed axial-flux machine which utilizes the idea of sinusoidal shaped pole combined with a consequent iron-pole. The target of the proposed machine is the cost reduction of the relatively expensive Samarium-Cobalt (SmCo) permanent magnet (PM) material and the torque per PM volume improvement by using sinusoidal consequent-pole rotor. The effectiveness of the proposed machine is validated by comparing it with conventional consequent-pole and with conventional PM machines using 3-D finite element method (FEM) simulations. The comparison and analysis is done in terms of back electro-motive force (back-EMF) harmonic contents, torque per PM volume and torque ripple characteristics. The simulation results show that the proposed machine is suitable and cost-effective for high-speed and high torque per PM volume applications. Furthermore, due to the consequent pole, the magnetic flux saturation and the overload current torque-capability are also presented and discussed in the paper.

• Archives of Plastic Surgery
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• v.44 no.6
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• pp.502-508
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• 2017

Background Breast-conserving therapy is defined as a breast-conserving wide local excision (WLE) of a mammary tumour combined with postoperative radiotherapy. Immediate restoration of the mammary shape by use of breast reduction techniques (volume displacement) or tissue replacement techniques (volume replacement) is gaining popularity to prevent breast malformation. Methods To date, using the internal mammary artery perforator (IMAP) flap has been suggested for immediate volume replacement after WLE, but has never been evaluated in a published study. Results We applied this flap in 12 women (mean age, 56.1 years) after WLE (mean specimen weight, 46.5 g) of the medial aspect of the breast. Over a median follow-up of 35.3 months (standard deviation, 1.2 months), 4 women needed repeated surgery for dog-ear correction of the donor site. Conclusions In our experience, the use of an IMAP flap was a reliable technique with good cosmetic outcomes after oncoplastic reconstruction. In this series, donor site revision often proved necessary initially, but we showed that this may easily be prevented.

• Journal of Environmental Health Sciences
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• v.40 no.6
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• pp.484-491
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• 2014

Objectives: A radon emission reducing agent was prepared using charcoal and zeolite, and the amount was measured after coating construction materials with the agent. The availability of the radon emission reducing agent was evaluated. Methods: Construction materials (red brick, cement brick, and gypsum board) coated with reducing agent were placed in a chamber to measure radon emissions. The construction materials were coated one through three times. The spread volume for brick and gypsum board was 50 mL and 75 mL per application, respectively. The amount of radon emitted was measured by RAD-7 after 48 hours. Results: The reduction ratio increased with the number of coatings, and the reduction ratios for red brick, cement brick, and gypsum board were 63.3, 73.6, and 58%, respectively, in the case of three coatings of RA-1. The reduction ratios for red brick, cement brick, and gypsum board were 42.8, 58.1, and 26.2%, respectively in the case of three coatings with RA-2. RA-1 was slightly better than RA-2 in radon emission reduction. Conclusions: Radon emissions from construction materials decreased according to the concentration of reducing agent coating, and it was more effective than existing methods.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.2
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• pp.181-187
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• 2009

In this study, a runoff hydrograph and runoff volume were calculated by using the kinetic wave theory for small urban watersheds based on the concept of low impact development(LID), and the effective imperviousness was estimated based on these calculations. The degree of sensitivity of the effective imperviousness of small watersheds to the impervious to pervious area ratio, infiltration capability, watershed slope, roughness coefficient and surface storage depth was then analyzed. From this analysis, the following conclusions were obtained: The effective imperviousness and paved area reduction factor decreased as the infiltration capability of pervious area increased. As the slope of watersheds becomes sharper, the effective imperviousness and the paved area reduction factor display an increasing trend. As the roughness coefficient of impervious areas increases, the effective imperviousness and the paved area reduction factor tend to increase. As the storage depth increases, the effective imperviousness and the paved area reduction factor show an upward trend, but the increase is minimal. Under the conditions of this study, it was found that the effective imperviousness is most sensitive to watershed slope, followed by infiltration capability and roughness coefficient, which affect the sensitivity of the effective imperviousness at a similar level, and the storage depth was found to have little influence on the effective imperviousness.

• Korean Journal of Metals and Materials
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• v.47 no.5
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• pp.304-310
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• 2009

Recently, manganese nodule has been focused on alternative resources because of its high grade of noble metallic elements such as Co, Ni, and Cu etc. From the viewpoint of an optimization the operating variables for energy efficiency of smelting reduction process, thermodynamic model for smelting reduction process of Manganese nodule was developed by using energy and material balance concept. This model provided that specific consumption of pure oxygen and coke was strongly depended on post combustion ratio (PCR) and heat transfer efficiency (HTE). The dressing and dehydrating process of low grade manganese can be proposed an essential process to minimize the specific energy consumption with decreasing slag volume. The effect of electricity coal base smelting reduction process was also discussed from the energy optimizing point of view.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.10
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• pp.920-927
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• 2013

The requirement of acoustic performance about underwater acoustic material which is used in underwater environment more increases. Underwater acoustic material was made by viscoelastic material such as a rubber and a polyurethane etc. In order to increase an acoustic performance, several kinds of inclusions were added to viscoelastic material. In this paper, acoustic modelling and analysis techniques were introduced and the acoustic characteristics of underwater acoustic material were studied. Echo reduction and transmission loss were calculated with volume fraction of inclusion in the material. Also the characteristic impedance and the input impedance of underwater acoustic material were obtained and effects on the echo reduction and transmission loss of material were discussed.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.632-635
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• 2007

Detention pond has an important role in peak flow reduction to mitigate flood damage. Design of detention pond is accomplished through the preliminary stage, planning stage, and design stage in general. New development projects produce increased peak flow and flow amounts. In this case it is necessary to design the detention pond easily and simply. The simple procedure of detention pond design is proposed in this study. The relevant variables are peak flow ratio ($\alpha$) for the before and after development, and storage ratio which is ratio of storage volume to flow amounts. Simplified method for the detention pond design with runoff reduction is easily used for practical purposes.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.963_964
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• 2009

This paper presents an output ripple reduction of Active-Clamp Forward Converter, which is mainly composed of interleaving two active-clamping forward converters. By interleaving, Output ripple is reduced. The leakage inductance of the transformer or an additional resonant inductance is employed to achieve ZVS during the dead times. The duty cycles are not limited to be equal and within 50%. The complementary switching and the resulted interleaved output inductor currents diminish the current ripple in output capacitors. Accordingly, the smaller output chokes and capacitors lower the converter volume and increase the power density. Detailed analysis of this ouput reduction of Active-Clamp Forward Converter is described.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.11
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• pp.1083-1090
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• 2004

Two noise reduction systems are proposed in order to overcome the geometric restriction of the reactive muffler such as an expansion chamber. First, membrane is installed as a part of a duct wall and an air cavity is covered outside membrane. Second, membrane is installed inside a duct, which gives no volume change of the duct. Structural-acoustic coupling between membrane and fluid inside the cavity and duct causes rapid impedance mismatching and thereby reflected wave. Theoretical prediction is conducted by using modal expansion approach. The results are compared with the experimental results, which show better noise reduction performance than an expansion chamber.