• Journal of Environmental Science International
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• v.19 no.8
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• pp.983-999
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• 2010

Wind power energy is one of the favorable and fast growing renewable energies. It is most important for exact analysis of wind to evaluate and forecast the wind power energy. The purpose of this study is to improve the performance of numerical atmospheric model by data assimilation over a complex coastal area. The benefit of the profiler is its high temporal resolution and dense observation data at the lower troposphere. Three wind profiler sites used in this study are inhomogeneously situated near south-western coastal area of Korean Peninsula. The method of the data assimilation for using the profiler to the model simulation is the three-dimensional variational data assimilation (3DVAR). The experiment of two cases, with/without assimilation, were conducted for how to effect on model results with wind profiler data. It was found that the assimilated case shows the more reasonable results than the other case compared with vertical observation and surface Automatic Weather Station(AWS) data. Although the effect of sonde data was better than profiler at a higher altitude, the profiler data improves the model performance at lower atmosphere. Comparison with the results of 4 June and 5 June suggests that the efficiency with hourly assimilated profiler data is strongly influenced by synoptic conditions. The reduction rate of Normalized Mean Error(NME), mean bias normalized by averaged wind speed of observation, on 4 June was 28% which was larger than 13% of 5 June. In order to examine the difference in wind power energy, the wind power density(WPD) was calculated and compared.

• Journal of Korean Foot and Ankle Society
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• v.13 no.2
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• pp.169-174
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• 2009

Purpose: To evaluate the clinical results between interlocking intramedullary nail with fibular fixation and nail only for treating distal tibiofibular diaphyseal fractures. Materials and Methods: From March 2003 to September 2006, 19 distal tibiofibular fractures were antegrade nailed after anatomical reduction and fixation of fibular fractures, and another 37 fractures fixed with nails only. Average age of patients was 48.6 years. These two groups were compared by VAS (visual analogue scale) & ankle ROM according to degree of comminution and fracture configuration. The statistical analysis was evaluated by t-test. Results: There was no statistical difference between fibular fixation group and non-fixation group in VAS score according to fracture comminution and configuration (p>0.05). However, compared according to fracture configuration, mean ankle eversion of fibular fixation group in oblique fractures was 18.3 degrees, and that of non-fixation group was 12.5 degrees (p<0.05). In addition, mean ankle plantar flexion, dorsiflexion, inversion and total ankle ROM of fibular fixation group in spiral fractures was 40.0, 20.0, 30.0 and 108.3 degrees of each and that of non-fixation group was 38.3, 18.5, 27.0 and 101.7 degrees (p<0.05). Conclusions: In oblique and spiral fractures of distal tibiofibular diaphysis, interlocking intramedullary nail with fibular fixation had the advantage in postoperative ankle ROM. So, it can be a worthy method for the treatment of distal tibiofibular diaphyseal fractures.

• Wind and Structures
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• v.26 no.4
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• pp.215-229
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• 2018

The appearance of a rivulet at the upper surface of a stay cable is responsible for rain-wind-induced vibration (RWIV) of cables of cable-stayed bridges. However, the formation mechanism of the upper rivulet and its aerodynamic effects on the stay cable has not been fully understood. Large eddy simulation (LES) method is used to investigate flow around and aerodynamics of a circular cylinder with an upper rivulet at a Reynolds number of 140,000. Results show that the mean lift coefficients of the circular cylinder experience three distinct stages, zero-lift stage, positive-lift stage and negative-lift stage as the rivulet located at various positions. Both pressure-induced and friction-induced aerodynamic forces on the upper rivulet are helpful for its appearance on the upside of the stay cable. The friction-induced aerodynamic forces, which have not been considered in the previous theoretical models, may not be neglected in modeling the RWIV. In positive-lift stage, the shear layer separated from the upper rivulet can reattach on the surface of the cylinder and form separation bubbles, which result in a high non-zero mean lift of the cylinder and potentially induces the occurrence of RWIV. The separation bubbles are intrinsically unsteady flow phenomena. A serial of small eddies first appears in the laminar shear layer separated from the upper rivulet, which then coalesces and reattaches on the side surface of the cylinder and eventually sheds into the wake.

• Journal of the Korean Solar Energy Society
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• v.35 no.5
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• pp.39-48
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• 2015

In this study, the solar chimney, one of the passive solar systems, is proposed as a method to improve the thermal environment of northern zones in buildings. As this well-known system has rarely been used in building projects, an adequate application of the system is proposed in this paper: the solar chimney system is designed to meet the required ventilation rate and consequently to reduce the ventilation load in the northern part of a building. To investigate such a possibility, a numerical model for the system is developed, and results of numerical tests are used for energy simulations. The results were taken into account for test simulations in EnergyPlus. As a result, approximately 75% of the volumetric ventilation rate required in the north zone could be supplied with the air volume acquired through the system and the monthly mean load was reduced by 29.5%, from 1.584 kWh to 1.117 kWh. The analyses of hourly mean heating and ventilation load over the heating period indicated that the system was very effective at around 13:00. Results show that 33% reduction in the ventilation load and 17% in the heating load for the north zone could be acquired through this system.

• Proceedings of the KOR-KST Conference
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• 1997.12a
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• pp.33-69
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• 1997

This study was conducted to develop a methodology to predict utility pole accident rates and to evaluate cost-effectiveness for safety improvement for utility pole accidents. The utility pole accident rate prediction model was based on the encroachment rate approach introduced in the Transportation Research Board Special Report 214. The utility pole accident rate on a section of highway depends on the roadside encroachment rate and the lateral extent of encroachment. The encroachment rate is influenced by the horizontal and vertical alignment of the highway as well as traffic volume and mean speed. The lateral extent of encroachment is affected by the horizontal and vertical alignment, the mean speed and the roadside slope. An analytical method to generate the probability distribution function for the lateral extent of encroachment was developed for six kinds of encroachment types by the horizontal alignment and encroachment direction. The encroachment rate was calibrated with the information on highway and roadside conditions and the utility pole accident records collected on the sections of 55mph speed limit of the State Trunk Highway 12 in Wisconsin. The encroachment rate on a tangent segment was calibrated as a function of traffic volume with the actual average utility pole accident rates by traffic volume strategies. The adjustment factors for horizontal and vertical alignment were then derived by comparing the actual average utility pole accident rates to the estimations from the model calibrated for tangent and level sections. A computerized benefit-cost analysis procedure was then developed as a means of evaluating alternative countermeasures. The program calculates the benefit-cost ratio and the percent of reduction of utility pole accidents resulting from the implementation of a safety improvement. This program can be used to develop safety improvement: alternatives for utility pole accidents when a predetermined performance level is specified.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.2
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• pp.211-218
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• 2000

This is a retrospective study on the nature and severity of zygomatic bone fractures. This study was based on a series of 358 patients with zygomatic bone fractures who treated as in-patient at Soonchunhyang Chonan Hospital during the period of Jan. 1993 through Dec. 1996. The results obtained are as follows : 1. The ratio of men to women was 4.41:1. The age frequency was highest in the second, third decade. The yearly distribution was the highest in 1993. The monthly distribution was highest in Feb. and Jun. 2. The most frequent cause was the traffic accident.(66.2%) 3. The most frequent type of fractures was the class I(undisplaced fx.).(25%) 4. The most frequent associated oral and maxillofacial injuries was soft tissue.(46.9%) 5. The most frequent associated systemic injuries was upper, lower extremity.(38%) 6. In A.I.S of oral and maxillofacial area, the mean score of A.I.S was $2.5{\sim}3$. In I.S.S, the highest mean score was in the ped TA.(19) 7. In respect of treatment, the most common method was open reduction with rigid fixation on fronto-zygomatic suture area.(47.8%) 8. The incidence of complication was 12% and the most common complication was malunion.(6.1%)

• Archives of Plastic Surgery
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• v.36 no.4
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• pp.428-431
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• 2009

Purpose: Blow out fracture resulting from facial trauma is of high frequency among facial bone fractures, and can cause severe complications. So, proper management and close observation after operation are needed. So far, Computed tomography has been the best choice in the evalution following orbit wall reconstruction. However, cost - effectiveness, accessibility to patients and hazard of radiation exposure of computed tomography require supplementary measure for the evaluation following orbit wall reconstruction. This study was performed to describe the effectiveness of ultrasonography in the evalution following orbit wall reconstruction. Methods: A retrospective study was performed on 40 patients who underwent orbit wall reconstruction from June, 2008 to July, 2008. The patients' ages ranged from 13 to 65 years (mean 27.5 years), and this group was compsoed of 27 male and 13 female patients. The follow up period ranged from 2 weeks to 28 weeks (mean 11weeks). Preoperatively, all fractures were diagnosed using computed tomography. Ultrasonography for all cases, and computed tomography for 2 cases were performed for evaluation following orbit wall reconstruction. Results: Reduction of herniated orbital soft tissue and orbit implant was identified by using ultrasonography in 38 cases out of 40 cases. In other cases which we could not identify the orbit implant, computed tomography was performed. Con clusion: Compared to computed tomography, ultrasonography is simple, inexpensive and convenient method. Ultrasonography can be used as supplementary measure to computed tomography in the evaluation following orbit wall reconstruction for elective patients.

• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.293-301
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• 2016

Objective: The purpose of this study was to analyze the effects of freezing of gait and visual information on the static postural control ability in patients with Parkinson's Disease (PD) during the bipedal stance with feet together. Method: This study included a total of 36 patients with PD; the freezer group included 17 PD patients (age: $69.3{\pm}6.2yrs$, height: $159.6{\pm}9.0cm$, weight: $63.4{\pm}9.78kg$) and the nonfreezer group included 19 PD patients (age: $71.4{\pm}5.6yrs$, height: $155.8{\pm}7.1cm$, weight: $57.7{\pm}8.6kg$). Static postural control ability was analyzed using variables of center of pressure (COP) and dividing by mediolateral, anteroposterior, and integration factors during a bipedal stance with the eyes open and closed. Results: Freezers and nonfreezers showed increases in anteroposterior velocity, mediolateral velocity, averaged velocity, and mediolateral 95% edge frequency when visual information was blocked. Additionally, freezers had greater anteroposterior range, 95% confidence ellipse area, and COP anteroposterior mean position than nonfreezers. Conclusion: Freezers and nonfreezers showed a reduction in static postural control ability when visual information was blocked. Additionally, the results of this study found a significant difference in static postural control ability between freezers and nonfreezers with PD. In particular, anteroposterior range, 95% confidence ellipse area, and COP anteroposterior mean position might be used to distinguish between freezers and nonfreezers with PD.

• Clinics in Shoulder and Elbow
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• v.9 no.1
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• pp.34-41
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• 2006

Purpose: This study is to analyze the result and complications of internal fixation with T-plate for two-part fracture of the neck of the humerus. Materials and Methods: The clinical results of fourteen patients who had been performed with this method mentioned above were reviewed. Their average age was 49.6. Postoperative mean follow up period was 24.1 months. Radiological evaluation was done by Kronberg's and shoulder function by Neer's. Results: By Kronberg evaluation, nine cases were good, two cases acceptable and three cases poor. By Neer's, mean score of shoulder function was 77.6 and 4 cases were excellent, one satisfactory, five unsatisfactory and four failure. The complications were the sfiff shoulder, loss of reduction and avascular necrosis of humeral head. Conclusion: In this study, there were differences according to the age. And we obtained an unsatisfactory result in patients over 50 years old. We consider that in patients over 50 years old, the differences were due to the muscle weakness through wide surgical approaches, postoperative implant loosening or the stiffness caused by poor rehabilitation.

• The Journal of the Acoustical Society of Korea
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• v.33 no.2
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• pp.146-151
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• 2014

This paper analyzes the previous Anjok model of the Gayageum and describes a method to improve the frequency modeling based on previous model. In the previous work, relation between the fundamental frequency and Anjok's location on the body is assumed as an exponential function and these frequencies are integrated by a first-order leaky integrator. Finally, a parameter of the formula to calculate the fundamental frequency is obtained by applying integrated frequencies to the linear regression. This model shows 2.5 Hz absolute deviation on average and has maximum error 7.75 Hz for the low fundamental frequencies. In order to overcome this problem, this paper proposes that the Anjok's locations are grouped according to the rate of error increase and linear regression is applied to each group. To find the optimal parameter, the RMSE(Root Mean Square Error) between measured and calculated fundamental frequencies is used. The proposed model shows substantial reduction in errors, especially maximum three times.