• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3366-3373
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• 2011

In this study, performance characteristics of a water source heat pump system using $CO_2$ as a refrigerant are investigated experimentally. Cooling and heating capacities and COP of the system are analyzed for various system performance variables such as refrigerant charge, expansion valve opening, compressor frequency and internal heat exchanger. Results show that optimum amount of refrigerant charge and expansion valve opening exists at maximum point of COP curve, and cooling capacity increases but COP decreases with the increase of compressor frequency. When the internal heat exchanger is installed, cooling capacity increases about 4.0% whereas heating capacity decreases about 0.89% compared to the case without internal heat exchanger.

• Steel and Composite Structures
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• v.34 no.1
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• pp.123-139
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• 2020

The tube outward local buckling of Concrete-Filled Steel Tube (CFST) beam under high compression stress is still considered a critical problem, especially for steel tubes with a slender section compared to semi-compact and compact sections. In this study, the flexural performance of stiffened slender cold-formed square tube beams filled with normal concrete was investigated. Fourteen (14) simply supported CFST specimens were tested under static bending loads, stiffened with different shapes and numbers of steel stiffeners that were provided at the inner sides of the tubes. Additional finite element (FE) CFST models were developed to further investigate the influence of using internal stiffeners with varied thickness. The results of tests and FE analyses indicated that the onset of local buckling, that occurs at the top half of the stiffened CFST beam's cross-section at mid-span was substantially restricted to a smaller region. Generally, it was also observed that, due to increased steel area provided by the stiffeners, the bending capacity, flexural stiffness and energy absorption index of the stiffened beams were significantly improved. The average bending capacity and the initial flexural stiffness of the stiffened specimens for the various shapes, single stiffener situations have increased of about 25% and 39%, respectively. These improvements went up to 45% and 60%, for the double stiffeners situations. Moreover, the bending capacity and the flexural stiffness values obtained from the experimental tests and FE analyses validated well with the values computed from equations of the existing standards.

• PNF and Movement
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• v.9 no.2
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• pp.21-27
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• 2011

Purpose : The purpose of this study was to investigate PNF exercise, the athletic performances and the ability of exercise capacity in Taekwondo. Methods : This is a literature study with books and articles, seminar note and books for PNF international course. Results : The PNF exercise was efficient at improving flexibility and muscle strengthening in Taekwondo athletes. Kinematic characters of Yupchagi and Dollyuchagi in Taekwondo were analogous to Lower extremity Flexion-Abduction-Internal Rotation patterns in PNF, and the kinematic character of Apchagi was to analogous to Lower extremity Flexion-Adduction-External Rotation pattern in PNF. Movements of Upper extremities and Lower extremities during kicking were similar to PNF patterns. The PNF is efficient at improving athletic performances and the ability of exercise capacity in Taekwondo. Conclusion : The result of this study showed that PNF patterns and kicking that is one of the basic movement in Taekwondo have many similarities. With that PNF patterns was the training methods to improve flexibility and muscle strengthening, PNF patterns are considered to improve athletic performances and the ability of exercise capacity in Taekwondo.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.48-51
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• 1996

A 5-bar structure with redundant actuators is proposed as a finger mechanism. It is shown that one additional redundant actuator greatly enhances the load handling capacity of the system. The actuator location should be carefully decided to maximize the performance enhancement. Furthermore, we develop stiffness and frequency control algorithms based on the internal loading created by redundant actuation. The effectiveness of these algorithms have been demonstrated by simulations.

• The Journal of Internal Korean Medicine
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• v.42 no.3
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• pp.375-384
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• 2021

Objective: This study was designed to analyze the clinical features of idiopathic pulmonary fibrosis patients who attended a Korean medicine hospital and the treatment effects through retrospective chart reviews. Methods: The medical records of 82 outpatients who had been diagnosed with idiopathic pulmonary fibrosis and visited the Allergy, Immune, and Respiratory System Department of Kyung Hee Korean Medicine Hospital from 8 January 2015 to 8 January 2021 were retrospectively reviewed. To assess the treatment outcomes, we used the FVC (Forced Vital Capacity), DLCO (Diffusing capacity of the Lung for CO), 6-minute walk test, and HRCT (High Resolution Computed Tomography). Results: The study group consisted of 28 females and 54 males. The median age of the patients was 67.98±11.44 years. The chief complaints were cough (n=51) and dyspnea (n=49). Other frequent symptoms were general weakness (n=8), weight loss (n=4), and a fever (n=2). A total of 77 (93.90%) patients were prescribed Korean herbal medicine, and 52 (63.41%) patients were treated with acupuncture, moxibustion, cupping therapy, ICT, or pharmacopuncture. After treatments, FVC, DLCO, the 6-minute walk test, and HRCT were maintained or worsened slightly. Conclusions: This study presented the characteristics of idiopathic pulmonary fibrosis patients treated by Korean medical therapies, and further studies of Korean medical treatments for idiopathic pulmonary fibrosis patients would be valuable.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2174_2175
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• 2009

This Paper present about loop impedance characteristic based on korea internal electrical environment. Analysis parameters were touch voltage, electrical shock current and human body resistance. Result, For protect of electrical shock must measuring of loop impedance. And current capacity & loop impedance are must important parameters.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.3
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• pp.174-181
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• 2018

This study introduces a systematic approach to selecting the internal parameters applied to the equivalent electrical-circuit model (EECM) of a lithium titanium oxide ($Li_4Ti_5O_{12}$; LTO) rechargeable cell. Based on the dynamic characteristic of the cell, a simplified EECM consisting of an open-circuit voltage (OCV), an ohmic resistance, and an RC ladder is fabricated. To select the internal parameters of a simplified EECM, experiments on discharge capacity, OCV, and discharge/charge resistances are performed using hybrid pulse power characterization and direct current internal resistance (DCIR) measurements over the full state-of-charge (SOC) range. The experimental results of the LTO rechargeable cell highlight the importance of correct selection of internal parameters that can reduce EECM errors. This study clearly provides experimental procedures, internal parameters results, and EECM guidelines for adaptive control-based SOC estimation for LTO rechargeable cells.

• Korean Journal of Computational Design and Engineering
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• v.22 no.1
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• pp.59-69
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• 2017

Internal capacity of a refrigerator is an important indicator for design and purchasing criteria. The components facing the internal space may have holes or gaps between parts. In traditional way, design engineers manually remodeled the parts to fill the holes and the gaps for enclosed boundary of the internal space. Then they calculated internal volume by subtracting the assembly of parts from its enclosing volume. However, filling holes and gaps is not an automated process requiring a plenty of labor and time. In this research, we have developed a voxel-based method to estimate the internal volume of a refrigerator automatically. It starts transforming all components facing the interior space into voxels and fills all holes and gaps automatically by the developed hole-filling algorithm to form a completely closed boundary of the assembly. Then, it identifies the boundary voxels that are facing to the internal voxels with any part of the component. After getting the intersection points between the boundary voxels and the surfaces of components, it generates the boundary surface of triangular facets with the intersection points. Finally, it estimates the internal volume by adding volume of each tetrahedron composed of a triangle of boundary surface and an arbitrary point.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.81-89
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• 1998

Numerical calculation tools for forging of gear-like components based on kinematically admissible velocity fields for upper bound method applicable to various deformation features of workpiece in forging processes were suggested. Each one of them deals with unidirectional flow of metal on dies, such as external involute spur gear. square spline, internal serrations. A complex calculation tool of gear-like component forging process was built up by combining these kinematically velocity fields. In this paper the workpiece with 110th external and internal teeth is divided into two parts. The deformation of each part is analyzed simultaneously using numerical calculation tool from combined kinematically admissible velocity field. The experimental set-up was installed in a 200 ton hydraulic press. As a result, each kinematically admissible velocity field could be combined with others and the calculated solution are useful to predict the capacity of forging equipment.

• International Journal of Advanced Culture Technology
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• v.10 no.3
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• pp.281-286
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• 2022

In this study, design of an intuitive internal resistance diagnostic device is to diagnose the residual capacity and aging of the battery regardless of the model and the internal protocol of the waste battery through the method of measuring the internal resistance of a waste battery. In this paper, charging and discharging were continuously performed with 2A charging and 5A discharging in order to secure data on impedance changes that may occur in the charging and discharging process of various methods. As a result of the final experiment, it was confirmed that the impedance change occurred during charging and discharging, and the amount of change increased as the charging/discharging C-rate increased. In addition, it was confirmed that the waste battery aged or abnormal cell had a large change in the impedance value.