• Imaging Science in Dentistry
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• v.34 no.4
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• pp.185-190
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• 2004

Purpose: To compare the diagnostic accuracy for the detection of root fractures in CMOS-based digital periapical images with conventional film-based periapical images. Materials and Methods: Sixty extracted single-root human teeth with closed apices were prepared endodontically and divided into two groups; artificially induced vertical root fracture group and control group. All radiographs were obtained using the paralleling technique. The radiographs were examined by 4 observers three times within a 4 week interval. Receiver operating characteristic (ROC) analysis was carried out using data obtained from four observers. Intra- and inter-examiner agreements were computed using kappa analysis. Results: The area under the ROC curve (Az) was used as an indicator of the diagnostic accuracy of the imaging system. Az values were as follows: direct-digital images; 0.93, film-based images; 0.92, and inverted digital images; 0.91. There was no significant difference between imaging modalities (P<0.05). The kappa value of inter-observer agreement was 0.42 (range: 0.28-0.60) and intra-observer agreement was 0.57 (range: 0.44-0.75). Conclusion : There is no statistical difference in diagnostic accuracy for the detection of vertical root fractures between digital periapical images and conventional periapical images. The results indicate that the CMOS sensor is a good image detector for the evaluation of vertical root fractures.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.96-101
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• 2005

Magnesium alloys have been widely used for many structural components of automobiles and aircraft because of high specific strength and good cast ability in spite of hexagonal closed-packed crystal structure of pure magnesium. In this study, uniaxial tension tests at high temperature and creep tests are done in order to investigate the characteristics of high temperature and mechanisms for creep deformation of AZ31 Mg alloy. Yield stress and ultimate tensile stress decreased with increasing temperature, but elongation increased from results of uniaxial tension test at high temperature. The apparent activation energy Qc, the applied stress exponent n and rupture life have been determined during creep of AZ31 Mg alloy over the temperature range of 473K to 573K and stress range of 23.42 MPa to 93.59 MPa, respectively, in order to investigate the creep behavior. Constant load creep tests were carried out in the equipment including automatic temperature controller, whose data are sent to computer. At around the temperature of $473K{\sim}493K$ and under the stress level of $62.43{\sim}93.59%MPa$, and again at around the temperature of $553K{\sim}573K$ and under the stress level of $23.42{\sim}39.00MPa$, the creep behavior obeyed a simple power-law relating steady state creep rate to applied stress and the activation energy for the creep deformation was nearly equal, respectively, and a little low to that of the self diffusion of Mg alloy including aluminum. Also rupture surfaces at high temperature have had bigger dimples than those at lower temperature by SEM.

• 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.

• Journal of Chest Surgery
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• v.30 no.12
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• pp.1167-1174
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• 1997

We retrospectively reviewed a series of 20 patients treated with delayed sternal closure during a 5-year period from 1991 to 1996. Of the 2675 patients with cardiovascular su gery 20 underwent this procedure. Male and female ratio was 11:9, mean age was 6.4 months(range 7 days to 5 years). The indications included unstable hemodynamic profiles after open heart surgery due to myocardial edema and poor lung compliance(15), necessity of mechanical ventricular assist device due to weaning failure(3), and hypoxia after PAB(2). Sternum was closed at a mean interval of 102(range 4 to 213) hours after operation. During delayed sternal closure, central venous pressure was elevated(p<0.05). Mediastinitis and other wound problems did not occur. Sepsis developed in 2 patients and microorganism was confirmed in one of the two patients. Five patients died(mortality 25%). And two of 15 discharged patients died during follow-up period. Cumulative survival rate was 65.0% at 12 months and also 65.0% at 24 months.(Standard error was 10.7%) Delayed sternal closure Is considered to be a good method to decompress the hemodynamically compromised heart. Without that, it is not f asible to come off bypass or to decompress the heart. Of course. careful selection of the indication is imperative.

• Archives of Reconstructive Microsurgery
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• v.25 no.2
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• pp.49-55
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• 2016

Purpose: Soft tissue defects in the lumbosacral area can be challenging to treat, and various methods to accomplish this have been proposed, including the use of perforator flaps. Herein, we present our experience with superior gluteal artery perforator (SGAP) and inferior gluteal artery perforator (IGAP) flaps for the reconstruction of lumbosacral defects. Materials and Methods: From March 2013 to July 2016, 28 cases (27 patients) of lumbosacral defects were treated by reconstruction with SGAP or IGAP flaps. The defects were caused by pressure sores (21 cases), burns (3 cases), tumor resection (2 cases), scars (1 case), or foreign body infection (1 case). Reliable perforators around the defect were found using Doppler ultrasound. The perforator flaps were elevated with a pulsatile perforator and rotated to cover the defects. Results: Twenty-three SGAP and 5 IGAP flap reconstructions were performed. The mean flap size was $9.2{\times}6.1cm^2$ (range, $5{\times}3cm^2$ to $16{\times}10cm^2$). Donor sites were closed by primary closure. Partial flap necrosis occurred in two cases, and minor complications of wound dehiscence occurred in 3 cases, which were healed by primary closure. The mean follow-up period was 4.4 months (range, 1~24 months). Conclusion: Gluteal-based perforator flaps can be safely harvested due to pliability and reliable vascularity in the gluteal area, reducing donor site morbidity without sacrificing the underlying muscles. Thus, these flaps are useful options for the reconstruction of lumbosacral defects.

• Journal of the Korean institute of surface engineering
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• v.45 no.6
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• pp.257-263
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• 2012

CrN/AlN multilayer coatings with various bilayer periods in the range of 1.8 to 7.4 nm were synthesized using a closed-field unbalanced magnetron sputtering method. Their crystalline structure, chemical compositions and mechanical properties have been investigated with Auger electron spectroscopy, X-ray diffractometry, atomic force microscopy, nanoindentation, scratch tests. The properties of the multilayer coatings varied strongly depending upon the magnitude of the bilayer period. The multilayer coating with a bilayer period of 1.8 nm showed the maximum hardness and an elastic modulus of approximately 37.6 and 417 GPa, respectively, which was 1.54 times higher than the hardness predicted by the rule of mixture from the CrN and AlN coatings. The hardness of the multilayer coating increased as the bilayer period decreased, i.e. as the rotation speed increased. The Hall-Petch type relationship, hardness being related to (1/periodicity)$^{-1/2}$, suggested by Lehoczky was confirmed for the CrN/AlN multilayer coatings with bilayer period close to the 5-10 nm range. With decreasing bilayer period, the surface morphology of the films became rougher and the critical load of films for adhesion strength gradually decreased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6C
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• pp.483-491
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• 2012

In vehicle-to-vehicle (V2V) communications, each vehicle should periodically disseminate a beacon message including the kinematics information, such as position, speed, steering, etc., so that a neighbor vehicle can better perceive and predict the movement of the vehicle. However, a simple broadcasting of such messages may lead to a low reception probability as well as an excessive delay. In this paper, we attempt to analyze the impact of the following key parameters of the beacon dissemination on the performance of vehicular networks: beacon period, carrier-sensing range, and contention window (CW) size. We first derive a beacon period which is inversely proportional to the vehicle speed. Next, we mathematically formulate the maximum beacon load to demonstrate the necessity of the transmit power control. We finally present an approximate closed-form solution of the optimal CW size that leads to the maximum throughput of beacon messages in vehicular networks.

• Journal of Microbiology
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• v.42 no.2
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• pp.99-102
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• 2004

Bacteriophage PM2 has a closed circular form of double stranded DNA as a genome. This DNA from the phage is a useful source for nick-circle endonuclease assay in the fmol range. Due to difficulties in the maintenance of viral infectivity, storage conditions of the phage should be considered for the puri-fication of PM2 DNA. The proper condition for a short-term storage of less than 2 months is to keep the PM2 phage at 4$^{\circ}C$; whereas the proper condition for a long-term storage of the PM2 phage for over 2 months is to keep it under liquid nitrogen in 7.5 ％ glycerol. The optimal conditions for a high yield of phage progeny were also considered with the goal to achieve a successful PM2 DNA preparation. A MOI(Multiplicity Of Infection) of 0.03, in which the OD$\sub$600/ of the host bacteria was between 0.3 and 0.5, turned out to be optimal for the mass production of PM2 phage with a burst size of about 214. Considerations of PM2 genome size, and the concentrations and radiospecific activities of purified PM2 DNA, are required to measure the endonuclease activity in the fmol range. This study reports the proper quantitation of radioactivity and the yield of purified DNA based on these conditions.

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.5
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• pp.291-297
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• 2011

The effect of cyclosporin A (CsA), an immunosuppressant, on human ether-a-go-go-related gene (HERG) channel as it is expressed in human embryonic kidney cells was studied using a whole-cell, patch-clamp technique. CsA inhibited the HERG channel in a concentration-dependent manner, with an $IC_{50}$ value and a Hill coefficient of $3.17{\mu}m$ and 0.89, respectively. Pretreatment with cypermethrine, a calcineurin inhibitor, had no effect on the CsA-induced inhibition of the HERG channel. The CsA-induced inhibition of HERG channels was voltage-dependent, with a steep increase over the voltage range of the channel opening. However, the inhibition exhibited voltage independence over the voltage range of fully activated channels. CsA blocked the HERG channels predominantly in the open and inactivated states rather than in the closed state. Results of the present study suggest that CsA acts directly on the HERG channel as an open-channel blocker, and it acts independently of its effect on calcineurin activity.

• Archives of Plastic Surgery
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• v.37 no.6
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• pp.795-800
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• 2010

Purpose: According to various medical publications, it is believed that epinephrine should not be injected in fingers. However numerous articles show the successful use of local anesthetic with epinephrine in the digits. Epinephrine-mixed lidocaine solution enables to maintain a bloodless field for operation and provides long duration of local anesthesia when patient was wide awake. Methods: From May 2009 to December 2009, ten patients underwent flexor tendon reconstruction with local anesthesia using epinephrine. No tourniquet was necessary. Before operation, all patients were injected with local anesthetics using 1% lidocaine 20 mL and 0.1% epinephrine 0.1 mL. Results: There was no case of digital necrosis nor gangrene in the epinephrine injection. All 10 patients actively could move the finger through a full range of motion. All procedures were performed without sedation nor tourniquet and we could obtain a good vision of operative field and patients were comfortable. The patient make his or her fingers move through a full range of active motion before the skin is closed. Phentolamine was not required to reverse the vasoconstriction in any patients. Conclusion: The assertation that epinephrine should not be injected into the fingers is clearly no longer valid. The epinephrine injection allowed the authors to adjust flexor tendon surgery without risks associated with general anesthesia. It also enables to ensure longer anesthetic duration and bloodless operative field, and prevent post operative complications. In case of flexor tendon surgery, the use of epinephrine injection is recommended because of the advantages of local anesthesia.