• ETRI Journal
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• v.38 no.1
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• pp.30-40
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• 2016

Co-channel interference between macro-femtocell networks is an unresolved problem, due to the frequency reuse phenomenon. To mitigate such interference, a secondary femtocell must acquire channel-state knowledge about a co-channel macrocell user and accordingly condition the maximum transmit power of femtocell user. This paper proposes a pilot-based spectrum sensing (PSS) algorithm for overlaid femtocell networks to sense the presence of a macrocell user over a channel of interest. The PSS algorithm senses the pilot tones in the received signal through the power level and the correlation metric comparisons between the received signal and the local reference pilots. On ensuring the existence of a co-channel macrocell user, the maximum transmit power of the corresponding femtocell user is optimized so as to avoid interference. Time and frequency offsets are carefully handled in our proposal. Simulation results show that the PSS algorithm outperforms existing sensing techniques, even at poor received signal quality. It requires less sensing time and provides better detection probability over existing techniques.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.323-326
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• 1992

In this paper, the active noise control(ANC) system using the inverse modeling techiniques is presented. The nonlinearity and time delay of the transfer function from the secondary speaker to the error microphone makes the ANC system have poor performance. To solve this problem, the inverse model technique and filtered-X LMS algorithm is using proposed. This proposed ANC system is implemented using DSP chip and operated in on-line. The experimental results show that this ANC system has better noise canceling performance than that used LMS only about 5-15[db]

• Korean Journal of Bronchoesophagology
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• v.3 no.1
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• pp.154-158
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• 1997

A case of squamous cell carcinoma of the thyroid gland associated with esophageal carcinoma is presented A squamous cell carcinoma of the thyroid gland is rare and is prognosis is poor. The histogenesis of squamous cell carcinoma is not clear, but at present, it is believed that most cases arise from the follicular epithelium It is very important to know whether squamous cell carcinoma of the thyroid is primary or secondary. Thus, the possibility of squamous cell carcinoma in the thyroid being the result of a metastasis or extension from a primary tumor in the trachea or esophagus must always be ruled out and intensive evaluation should be required to confirm the diagnosis of this disease. We report a squamous cell carcinoma of the thyroid associated with esophageal cancer with brief review of literature.

• Journal of Trauma and Injury
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• v.36 no.1
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• pp.60-64
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• 2023

Upper extremity vascular injuries occurring with acute compartment syndrome are very challenging to manage in an emergency context in resource-poor settings. The need to always recognize the likelihood of coexisting compartment syndrome guides surgeons to perform concomitant fasciotomy to ensure a better outcome. We managed three vascular injuries in the upper extremities in two patients with concomitant imminent compartment syndrome observed intraoperatively. The first injury was complete brachial artery disruption following blunt trauma, while the second and third injuries were radial and ulnar artery transection caused by sharp glass cuts. Both patients were treated with vascular repair and fasciotomy. Secondary wound coverage was applied with split-thickness skin grafting, and the outcomes were satisfactory. Concomitant fasciotomy potentially improves the outcomes of vascular repair in emergency vascular surgery and should be considered for all injuries with the potential for acute compartment syndrome.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1536-1545
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• 2008

In this paper, we research a new method for efficiency improvement of a single-phase Induction motor by minimization of the stator loss. To make this, we perform winding design which is based on balanced and quasi-balanced operation condition. It gives efficiency improvement greatly but poor starting torque simultaneously. To obtain the best efficiency improvement maintaining the maximum and starting torque, the optimal winding specification and rotor dimension is determined with variation of secondary resistance, running capacitor and turn ratio. Finally, this paper gives the comparison between the simulation results and experimental results.

• Journal of the Korean Ceramic Society
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• v.28 no.4
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• pp.269-278
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• 1991

Fine AlN powder was synthesized by carbothermal reduction and nitridation of alumimun hydroxide prepared from Al-isopropoxide. AlN ceramics with Y2O3 and CaO were prepared by hot-pressing under the pressure of 30 MPa at 180$0^{\circ}C$ for 1 h in N2 atmosphere. Grain boundary behavior and purification mechanism of AlN lattice were examined by heat treatment of AlN ceramics at 185$0^{\circ}C$ for 1-6 h in N2 atmosphere. AlN ceramics without sintering additives showed poor sinterability. However, Y2O3-doped and CaO-doped AlN ceramics were fully densified nearly to theoretical density. As the heat treatment time increased, c-axis lattice parameter increased. This is attributed to the removal of Al2O3 in AlN lattice. This purification effect of AlN attice depended upon the quantity of secondary oxide phase in the inintial stage of heat treatment and the heat treatment time.

• Journal of Magnetics
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• v.16 no.3
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• pp.216-219
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• 2011

Mn doped ZnO films were prepared on Si (100) substrates using sol-gel method. The prepared films were annealed at $550^{\circ}C$ for decomposition and oxidation of the precursors. XRD analysis revealed the presence of ZnMnO hexagonal wurtzite phase along with the presence of small quantity of $ZnMn_2O_3$ secondary phase and poor crystalline nature. The 2D, 3D views of magnetic domains and domain profiles were obtained using magnetic force microscopy at room temperature. Rectangular shaped domains with an average size of 4.16 nm were observed. Magnetic moment measurement as a function of magnetic field was measured using superconducting quantum interference device (SQUID) magnetometry at room temperature. The result showed the ferromagnetic hysteresis loop with a curie temperature higher than 300 K.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.6
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• pp.39-46
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• 2010

Linear induction motor is adopted as an actuator of the planar stage. An inherently poor characteristic at zero or ultra-low speed zone of the induction motor is remarkably improved due to a recent development of power electronic semiconductor technology and a spatial vector control theory. At present, a servo response speed of the induction motor reaches 90 percent of one of PM synchronous or BLDC motor. Specially, as a secondary of the induction motor can be constructed using uniform conducting sheets, there is no periodic force ripple as in PM motors. So, the induction motor can be superior to another driving means under a certain condition. This paper discusses the overall development procedure of non-contact planar stage with a big workspace using linear induction motors.

• Journal of Chest Surgery
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• v.23 no.6
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• pp.1139-1145
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• 1990

Seven infants less than age 3 months underwent patch aortoplasty and tube graft bypass for relief of coarctation of aorta. All had intractable congestive heart failure, despite aggressive medical therapy Each infant had other cardiac anomalies including patent ductus arteriosus, ventricular septal defect, atrial septal defect and congenital mitral stenosis. All patients underwent closure of the ductus arteriosus and patch angioplasty of the aorta to produce a luminal diameter of at least 15mm or tube graft interposition utilizing the Gortex tube graft diameter larger than 10mm. In 5 patients who had ventricular defect, they underwent pulmonary arterial banding. &ere was one hospital death 17 days after operation secondary to the hydronephrosis and renal failure. Hospitalization was less than 10 days after operation except one case. In 3 patients who had associated VSD, open heart surgery[VSD closure+PA debanding]was done without difficulty. Surgical repair of critical coarctation of the aorta in infants can safely be offered despite the poor preoperative condition and presence of other cardiac anomalies.

• Journal of Chest Surgery
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• v.15 no.4
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• pp.373-380
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• 1982

Experience with intracardiac surgery in infants indicates that for most anomalies the operation and late mortality after primary total correction is lower than the combined mortality after early palliation and delayed correction. In addition, there are secondary benefits of primary total correction in terms of reversal of retarded physical growth and social development and alleviation of parental anxiety. One hundred and fifteen infants under 2 years of age with congenital cardiac anomalies underwent primary surgical intervention at Seoul National University Hospital from Jan. `78 to Sep. `82. There were 70 patients with VSD, 17 patients with TOF, 10 patients with TGA, 4 patients with ASD, 4 patients with TA, 3 patients with TAPVR, and the remainders are Coronary AV Fistula, partial ECD+COA, SV, DORV, PA, Trilogy+PDA. The overall surgical mortality was 18.3%. In acyanotic group 6 patients died among 76 operated patients, and surgical mortality was 6.6%. But in cyanotic group, the mortality was very high as41.0% [16 patients among 39 patients]. This poor surgical result in cyanotic group was due to Improper pre-, intra- and post-operative care, and we are convincing that these factors soon be improved as experiences accumulated.