• Journal of Korean Foot and Ankle Society
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• v.11 no.1
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• pp.91-96
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• 2007

Purpose: To evaluate the clinical results and determine appropriate methods of surgical treatment about type II talar neck fracture. Materials and Methods: Among nineteen patients who received surgical treatment for type II talar neck fracture from May 2000 to May 2005. Fourteen patients with a follow-up period of more than 1 year were divided into two groups. Six patients reduced by closed reduction (Group A) with screw fixation and eight patients reduced by open reduction with screw fixation. We analyzed preoperative, postoperative and follow-up simple radiographs and reviewed patient hospital records retrospectively. Clinical results were evaluated by Hawkins scoring system. We analyzed pain, limp, range of motion of ankle and subtalar joint. Results: Five patients (83.3%) in group A and seven patients (87.7%) in group B had excellent and good clinical results. There were no complications including avascular necrosis, delayed union, nonunion. Conclusion: Closed reduction with screw fixation of talar neck fracture shows correct reduction and satisfactory results. But because of short term period of follow-up, we need long term results.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.31-36
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• 2009

There have been many solar tracking systems developed for the high accuracy in solar tracking. One of the key components of any motion control system is software. LabVIEW offers an ideal combination of flexibility, ease-of-use and well-integration with other I/O pieces for developing solar tracking system. Real-time solar positions which vary with GPS's data are used simultaneously to control the solar tracker by a chain of operating modes between the open and closed loops. This paper introduces a step by step procedure for the fabrication and performance assessment of a precision solar tracking system. The system developed in this study consists of motion controllers, motor drives, step-motors, feedback devices and application. CRD sensors are applied for the solar tracking system which play a primary role in poor conditions for tracking due to a gear backlash and a strong wind. Mini-dish was used as a concentrator for collecting sun light. The solar position data, in terms of azimuth and elevation, sunrise and sunset times was compared with those of KASI(Korea Astronomy & Space Science Institute). The results presented in this paper demonstrate the accuracy of the present system in solar tracking and utilization.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.1
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• pp.43-48
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• 2022

Although the distribution system has been structured as complicated as a mesh in the past, the connection points for each line are always kept open, so that it is operated as a radial distribution system (RDS). For RDS, the line utilization rate is determined according to the maximum load on the line, and the utilization rate is usually kept low. In addition, when a fault occurs in the RDS, a power outage of about 3 to 5 minutes occurs until the fault section is separated, and the healthy section is transferred to another line. To improve the disadvantages of the RDS, research on the construction of a networked distribution system (NDS) that linking multiple lines is in progress. Compared to the RDS, the NDS has advantages such as increased facility utilization, load leveling, self-healing, increased capacity connected to distributed generator, and resolution of terminal voltage drop. However, when a fault occurs in the network distribution system, fault current can flow in from all connected lines, and the direction of fault current varies depending on the fault point, so a high-precision fault current direction determination method and high-speed communication are required. Therefore, in this paper, we propose an accurate fault current direction determination method by comparing the peak value polarity of the fault current in the event of a fault, and a communication-based protection coordination method using this method.

• Structural Engineering and Mechanics
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• v.31 no.1
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• pp.39-56
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• 2009

Vibration is an undesirable phenomenon in a dynamic system like lightly damped aerospace structures and active vibration control has gradually been employed to suppress vibration. The objective of the current investigation is to introduce an active torsional magneto-rheological (MR) fluid based damper for vibration control of a typical nose landing gear. They offer the adaptability of active control devices without requiring the associated large power sources. A torsional damper is designed and developed based on Bingham plastic shear flow model. The numerical analysis is carried out to estimate the damping coefficient and damping force. The designed damper is fabricated and an experimental setup is also established to characterize the damper and these results are compared with the analytical results. A typical FE model of Nose landing gear is developed to study the effectiveness of the damper. Open loop response analysis has been carried out and response levels are monitored at the piston tip of a nose landing gear for various loading conditions without damper and with MR-damper as semi-active device. The closed-loop full state feedback control scheme by the pole-placement technique is also applied to control the landing gear instability of an aircraft.

• Journal of Korean Neurosurgical Society
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• v.42 no.4
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• pp.305-310
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• 2007

Objective : Combined antero-posterior fixation has been a standard method for bilateral interfacetal dislocation in cervical spine. The purpose of this study is to evaluate the efficacy and complication of anterior cervical stabilization in treatment of bilateral interfacetal dislocation. Methods : A total of 65 cases of traumatic bilateral interfacetal dislocation in cervical spine who were managed in our institution, from Mar. 1997 to Feb. 2006, were included in this study. Closed reduction was tried in all cases before operation. If closed reduction was accomplished successfully, only anterior cervical fixation was performed (Group I), and attempted to place screws bicortically as possible with unicortical screws. If failed, posterior open reduction with fixation was first tried, followed by anterior cervical fixation (Group II). All patients were evaluated for neurological outcome and radiological evidence of healing. Results : The Group I included 47 patients and the Group II, 18 patients. The improvement of Frankel grade and increase of mean cervical lordosis angles were not statistically different between two groups. Screw-plate system used did not influence the outcome. On follow up, solid bone fusion was evident and there were no cases of instability in both groups. Conclusion : Our study demonstrated that anterior cervical fixation on BID is safe and effective in comparison with combined antero-posterior cervical fixation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.151-157
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• 2011

This study analyzed the posture balance of time variation for exercising body a period of time. Posture balance measured output values for the posture balance system of body moving in the multi-parameter. Posture moving variation had three methods such as open and closed eye, head moving and upper body moving. There were checked a parameter that measured vision, vestibular, somatosensory, CNS. This system was evaluated a data through the stability. This system has catched a signal for physical condition of body data such as a data acquisition system, data signal processing and feedback system. The output signal was generated Fourier analysis that using frequency of 0.1Hz, 0.1-0.5Hz, 0.5-1Hz and 1Hz over. The posture balance system will be used to support assessment for body moving the posture balance of time variation. It was expected to monitor a physical parameter for health verification system.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.1
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• pp.49-54
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• 2012

The purpose of this study is to define emergency response procedures by BDMS [Building Disaster Management System] when earthquake occurs on long-span bridge structures. The study is about developing a computer-based algorithm for various earthquake intensities that works with the System. Presently, long-span bridge disaster prevention relies on closed-system centered on human intervention alone. However, this study combines IT technology and internet-based open system creating a more practical system. Additionally, assigned duties and tasks are clearly defined to all personnel involved in various disaster situations using the Active Action Diagram(AAD) techniques. Also, the design of 3-dimensional view assists to determine the appropriate initial response in times of earthquake and other disasters. The combination of the existing manual emergency response procedures and the scenario-based (IT) response system being developed will create an efficiency and fast response actions in times of emergencies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.6
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• pp.477-482
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• 2017

When using the FDM to create a 3D object, a thermoplastic filament is heated to its melting point and then extruded layer by layer. Although the FDM printing process has many advantages, its accuracy, and surface finish are not satisfactory. In recent years, much research has been devoted to improving the accuracy of the FDM printing process. The temperature difference between the nozzle and the interior of the chamber of a 3D printer is one of the important parameters affecting the printing process. In this study, we propose a methodology to reduce this temperature difference through design improvement. In addition, we elucidate how this design improvement affects product quality. The FDM printing process is conventionally carried out in a closed chamber. However, in this study, an open heating system is used to reduce the temperature. The FDM printing processes were simulated using FEM analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.376-379
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• 2004

The purpose of this work is to develop an effective active control system for combustion instabilities of premixed combustors. For the first step, the natural modes of combustion oscillation were investigated for a methane-air premixed combustor and the controls by secondary fuel injection were examined. The main premixed flame is stabilized by a swirler with orifices for secondary injection installed on the central hub. For sensing purposes, a pressure transducer and a chemiluminescence sensor were placed on the appropriate positions. The acoustic characteristics and the source of the oscillation were analyzed by those signals. To test the controllability, two methods of actuations by secondary fuel injection were examined. One is the open loop control and the other is the closed loop control. The comparison of the reduction levels of p $_{rms}$ shows that the closed loop control with a phase-shift injection performs best in this condition.ition.n.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.2
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• pp.79-87
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• 2002

This landscape design proposal was presented to a design competition for the KangWon Province Police Agency(KPA). The site, about 27,711 $m^2$, is located at 293-4 Udu-dong, Chunchun, KangWon-Do. Design objectives of the KPA were to build a symbolic place which fall community members with pride, to elevate an identity and status of the KPA by creating a landscape correspondent to the concept of the building design, to provide community residents with a space to enjoy cultural and social activities, and to make environment friendly space. The main concept was developed by one of characteristics of the traditional spatial structure of Korea known as an, 'Open and Closed spatial structure.'By re-interpreting the traditional spatial structure and applying it to the site, the design met the various desires of the KPA. The site is primarily segmented into 6 sub spaces; entrance space Podori plaza, symbolic court, police billeting area, sports area, and rear rest area. The entrance space, Podori plaza, and symbolic court on the south-west part of the site represent the publicity of the site as the concept of ″open space.″ On the contrary, considering the specialty of police affairs, the north-east part of the site, which contains the police billeting area and rest area, were designed to maintain security by using the concept of ″closed space.″ To express an identity of the KPA, 'Podori', a police mascot, the plaza was designed and is suppose to function as the hub of the community. In the front section of the plaza, a symmetrical planting pattern, centering the strong axis, was introduced to strengthen its symbolic meaning. Traditional window frames such as the pattern of 'Pisal-jige'and 'Umulsal-jige' were used for the paving system which is applied as the environment friendly design. Site facilities and furnitrue were placed at every important spot in order to connect various spaces organically. As these well-tied spaces properly shared their function, spatial sequence and management would be promoted. The entire space was designed to allow free access of handicapped people. This proposal is meant to create a new image of KangWon province and to enhance the way of inhabitants' think about their community.