• Journal of Korean Orthopaedic Sports Medicine
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• v.9 no.1
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• pp.16-21
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• 2010

The prevalence of overuse syndrome in the lower extremity including chronic compartment syndrome and stress fracture is increasing with popularity of sports activities. Chronic compartment syndrome is defined as elevation of the interstitial pressure during exertional activities in a closed osseofascial compartment that results in microvascular compromise and operative procedures can be necessary if conservative treatments fail. Stress fracture can be classified as fatigue and insufficiency fracture; stress fracture occurs by repeated strain under abnormal conditions from the patient's activity whereas insufficiency fracture does by those from a process intrinsic to the bone. Most stress fractures occur in the lower extremity, most commonly in the tibial region. Fatigue fractures begin in athletes with the change in their training programs. The radiographic findings are usually diagnostic or at least strongly suggestive and MRI has proven to be a beneficial diagnostic tool for difficult diagnostic cases. Fatigue fractures are treated with a decrease in activity, but surgical procedure may be necessary in those in anterior cortex of the tibial diaphysis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.125-134
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• 2004

The new deregulated economic environment in the power utility market is forcing fundamental changes in the investment and operational decisions regarding transmission lines. Hence, it has come to be an important issue to evaluate their current utility in order to increase conductor ampacity based on conservative assumptions of worst case weather conditions. Static thermal rating has born still applied in most power companies worldwide, however some of them have been done various trials such as monitoring dynamic line ratings to increase line ratings in real time. This study is an attempt to access the static line ratings in Korea Electric Power Corporation(KEPCO) transmission lines, which were specified by weather model. Several environmental performances for determining static line ratings are examined by using the past weather data of Korean Meteorological Administration. As a result, it is shown that seasonal or regional line ratings could be adopt to the KEPCO's transmission lines, and their line ratings could be more increased without refurbishing current conductors in service to new high-temperature ones.

• Clinical and Experimental Pediatrics
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• v.54 no.4
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• pp.169-175
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• 2011

Purpose: Acute internal hemorrhage is an occasionally life-threatening complication in pediatric cancer patients. Many therapeutic approaches have been used to control bleeding with various degrees of success. In this study, we evaluated the efficacy of selective internal iliac artery embolization for controlling acute intractable bleeding in children with malignancies. Methods: We retrospectively evaluated the cases of 6 children with various malignancies (acute lymphoblastic leukemia, acute myelogenous leukemia, chronic myelogenous leukemia, T-cell prolymphocytic leukemia, Langerhans cell histiocytosis, and rhabdomyosarcoma), who had undergone selective arterial embolization (SAE) of the internal iliac artery at the Chonnam National University Hwasun Hospital between January 2004 and December 2009. SAE was performed by an interventional radiologist using Gelfoam$^{(R)}$ and/or Tornado$^{(R)}$ coils. Results: The patients were 5 boys and 1 girl with median age of 6.9 years (range, 0.7-14.8 years) at the time of SAE. SAE was performed once in 4 patients and twice in 2, and the procedure was unilateral in 2 and bilateral in 4. The causes of hemorrhage were as follows: hemorrhagic cystitis (HC) in 3 patients, procedure-related internal iliac artery injuries in 2 patients, and tumor rupture in 1 patient. Initial attempt at conservative management was unsuccessful. Of the 6 patients, 5 (83.3%) showed improvement after SAE without complications. Conclusion: SAE may be a safe and effective procedure for controlling acute intractable hemorrhage in pediatric malignancy patients. This procedure may obviate the need for surgery, which carries an attendant risk of morbidity and mortality in cancer patients with critical conditions.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.2
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• pp.143-152
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• 1998

The aerosol concentrations of ionic components were measured on a daily basis from a coastal monitoring site located at Kosan, Cheju Island from 26 September to 5 October 1997 as a field-intensive for a LRTAP project The chemical species we investigated include most of important inorganic species (i.e., Cl-, NO3-, F-, SO42-, Na+, NH4+, and K+) and some organic species (i.e. formats, acetate, and methanesulfonate (MSA) ions). The concentration data of those important inorganic and organic species obtained during this study were evaluated to properly address their chemical and physical characteristics. Most of major inorganic components including sulfate, sodium, chloride, and potassium ions exhibited very conservative relationships with each other such that the concentration ratios of any pair are quite analogous to that of seawater ratio. Since the oceans serve as the major sources of ionic constituents, their concentration changes appear to be senstively reflected by the factors affecting air-sea processes such as an increase in wind speed or changes in wind direction. A comparative analysis of sulfur-containing species such as seasalt (SS) and nonseasalt (NSS) sulfate and MSA were also made to assess the factors influencing the S cycling. An evaluation of NSS/SS ratios suggests that most of sulfate be associated with NSS fraction rather than 55 one. The finding of lower MSA/NSS-SO42- ratio along with a line of physical evidence such as intrusion of anthropogenically affected air mass suggests that the oxidation of S species have been promoted under the conditions encountered during the study period. Finally, the concentration data of carboxylic species (such as formats and acetate ions) were also analyzed. Although the existence of temporal trends were difficult to assess, these data indicate that their contribution to the precipitation acidity may not be significant enough.

• Journal of Korean Orthopaedic Sports Medicine
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• v.11 no.1
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• pp.8-16
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• 2012

With the increase of participation in the sport activities, there has been a commensurate rise in the number of sport injuries. A more commonly encountered injured region in the upper-extremity is the wrist. Sport injuries are often characterized as overuse and traumatic. Traumatic injuries include fractures, dislocations, and ligament tears often seen in contact or collision sports. Overuse injuries, represented damages by a level of repetitive microtrauma sufficient to overwhelm the tissues$^{\circ}{\O}$ ability to adapt, include inflammatory conditions such as De Quervain$^{\circ}{\O}s$ disease, extensor carpi ulnaris tendinitis, intersection syndrome. Also included is a traumatic problem such as stress fractures of the hook of the hamate, subluxation of the extensor carpi ulnaris tendon, chronic scapholunate instabilities, and degenerative triangular fibrocartilage tears. This review will focus on both overuse and traumatic injuries of the wrist in the athletes. A significant emphasis will be placed on the evaluation, pearls and pitfalls of conservative and operative treatments.

• Journal of Communications and Networks
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• v.8 no.1
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• pp.70-84
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• 2006

We propose a new distributed QoS routing scheme called pre-computation based selective probing (PCSP). The PCSP scheme is designed to provide an exact solution to the constrained optimization problem with moderate overhead, considering the practical environment where the state information available for the routing decision is not exact. It does not limit the number of probe messages, instead, employs a qualitative (or conditional) selective probing approach. It considers both the cost and QoS metrics of the least-cost and the best-QoS paths to calculate the end-to-end cost of the found feasible paths and find QoS-satisfying least-cost paths. It defines strict probing condition that excludes not only the non-feasible paths but also the non-optimal paths. It additionally pre-computes the QoS variation taking into account the impreciseness of the state information and applies two modified QoS-satisfying conditions to the selection rules. This strict probing condition and carefully designed probing approaches enable to strictly limit the set of neighbor nodes involved in the probing process, thereby reducing the message overhead without sacrificing the optimal properties. However, the PCSP scheme may suffer from high message overhead due to its conservative search process in the worst case. In order to bound such message overhead, we extend the PCSP algorithm by applying additional quantitative heuristics. Computer simulations reveal that the PCSP scheme reduces message overhead and possesses ideal success ratio with guaranteed optimal search. In addition, the quantitative extensions of the PCSP scheme turn out to bound the worst-case message overhead with slight performance degradation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.531-542
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• 2011

The time-dependent temperature distribution across the section in bridges is determined on the basis of the three-dimensional finite element analyses and numerical time integration in this study. The material properties which change with time and thermal stress of concrete are taken into account to effectively trace the early-age structural responses. Since the temperature distribution is nonlinear and depends upon many material constants such as the thermal conductivity, specific heat, hydration heat of concrete, heat transfer coefficients and solar radiation, three representative influencing factors of the construction season, wind velocity and bridge pavement are considered at the parametric studies. The validity of the introduced numerical model is established by comparing the analytical predictions with results from previous analytical studies. On the basis of parametric studies for four different bridge sections, it is found that the creep deformation in concrete bridges must be considered to reach more reasonable design results and the temperature distribution proposed in the Korean bridge design specification need to be improved.

• Journal of Korean Foot and Ankle Society
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• v.24 no.1
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• pp.25-30
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• 2020

Purpose: Generally, the treatment of ankle trimalleolar open fractures is divided into two stages: external fixation and debridement; and secondary internal fixation. On the other hand, this two-stage operation takes considerable treatment time and is challenging in procedures requiring reduction. The purpose of this study was to evaluate the radiologic and clinical results of an immediate one-stage internal fixation operation considering the wound conditions to overcome two stage operation disadvantages. Materials and Methods: From September 2009 to January 2018, 24 cases of ankle trimalleolar open fractures, who underwent immediate internal fixation and were followed up for at least one year, were studied retrospectively. The open wound was divided into the Gustilo-Anderson classification. Open reduction and internal fixation were performed on every medial and lateral malleolar fracture. On the other hand, with posterior malleolar fractures, surgical or conservative treatment was performed depending on the fragment size. The radiologic outcome was evaluated using the Burwell and Charnley criteria and American Orthopaedic Foot and Ankle Society (AOFAS) scores, and complications, such as infection and posttraumatic arthritis, were used for the clinical evaluation. Results: The wound was classified into eight cases (33.3%) of type I, 11 cases (45.8%) of type II, and five cases (20.8%) of type IIIa. The degree of reduction was anatomical, fair, and poor in 16 cases (66.7%), six cases (25.0%), and two cases (8.3%), respectively. The mean AOFAS score was 79 points, and there were complications, such as infection in three cases (12.5%) and post-traumatic arthritis in two cases (8.3%). Conclusion: Satisfactory results were obtained through immediate surgical treatment in ankle trimalleolar open fractures of types I, II, and IIIa.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.2
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• pp.175-179
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• 2003

Convergence condition determines performance of iterative learning control (ILC), for example, convergence speed, remaining error, etc. Hence, the performance can be elevated and a feasible set of learning controllers grows if a less conservative condition is obtained. In the frequency domain, the $H_{\infty}$ norm of the transfer function between consecutive errors has been currently used to test convergence of a learning system. However, even if the convergence condition based on the $H_{\infty}$ norm has a clear property about monotonic convergence, it has a few drawbacks, especially in MIMO plants. In this paper, the relation between the condition and the monotonicity of convergence is clarified and a modified convergence condition is found out using a frequency domain Lyapunov equation, which supersedes the conventional one in the frequency domain.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.1
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• pp.62-69
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• 2020

This study intended to evaluate noise level of dental handpieces and the effects of noise cancelling devices. An ear model was designed to measure the level of the noise delivered to the inner ear during dental handpiece operation. The level of noise was measured in various conditions using the ear model and the portable noise meter. Noise level was measured again after applying of 4 different noise cancelling devices to the model ear. The noise level of dental handpieces was 82.5 - 84.4 dB. When 4 types of noise canceling devices were applied, the noise level reduced to 67.4 - 73.8 dB. All 4 devices had statistically significant effect in reducing the noise of the handpiece. Considering the intensity and exposure time, noise in dental clinics can cause hearing damage to dentists. For protection from the risk of occupational hearing damages, noise canceling devices can be recommended.