• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.8
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• pp.750-757
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• 2011

Wireless Sensor Network is composed of a lot of sensor nodes that are densely deployed in a field. So generally this sensor nodes are spreaded using Helicopter or Fixed wing. Each node delivers own location and acquired information to user when it detects specific events. In this paper, we propose localization algorithm without range information in wireless sensor network using helicopter. Helicopter broadcasts periodically beacon signal for sensor nodes. Sensor nodes stored own memory this beacon signal until to find another beacon point(satisfied special condition). This paper develops a localization mechanism using the geometry conjecture(perpendicular bisector of a chord) to know own location. And the simulation results demonstrate that our localization scheme outperforms Centroid, APIT in terms of a higher location accuracy.

• Korean Journal of Optics and Photonics
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• v.22 no.5
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• pp.207-213
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• 2011

We propose a new method to measure the phase errors of an AWG(arrayed waveguide grating) through Monte-Carlo analysis. In the frequency domain method, we used the Monte-Carlo method to fit the theory to the experimental results. The phase and amplitude values are obtained from the fitted theory. To verify our method, we carried out a simulation. Some phase errors were included to make a virtual interferogram and we measured the actual AWG phase errors from it by our method. The results show that our method gives good results if the laser tuning range is larger than 1.7 times of the AWG FSR(free spectral range) and if the phase errors are within ${\pm}50^{\circ}$.

• Smart Structures and Systems
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• v.21 no.3
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• pp.279-286
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• 2018

The free longitudinal vibration of a circular truncated nanocone is investigated based on the nonlocal elasticity theory. Exact analytical formulations for tapered nanostructures are derived and the nonlinear differential governing equation of motion is developed. The nonlocal small scale effect unavailable in classical continuum theory is addressed to reveal the long-range interaction of atoms implicated in nonlocal constitutive relation. Unlike most previous studies applying the truncation method to the infinite higher-order differential equation, this paper aims to consider all higher-order terms to show the overall nonlocality. The explicit solution of nonlocal stress for longitudinal deformation is determined and it is an infinite series incorporating the classical stress derived in classical mechanics of materials and the infinite higher-order derivative of longitudinal displacement. Subsequently, the first three modes natural frequencies are calculated numerically and the significant effects of nonlocal small scale and vertex angle on natural frequencies are examined. The coupling phenomenon of natural frequency is observed and it is induced by the combined effects of nonlocal small scale and vertex angle. The critical value of nonlocal small scale is defined, and after that a new proposal for determining the range of nonlocal small scale is put forward since the principle of choosing the nonlocal small scale is still unclear at present. Additionally, two different types of nonlocal effects, namely the nonlocal stiffness weakening and strengthening, reversed phenomena existing in nanostructures are observed and verified. Hence the opposite nonlocal effects are resolved again clearly. The nano-engineers dealing with a circular truncated nanocone-based sensors and oscillators may benefit from the present work.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.1
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• pp.51-62
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• 2010

The high concentration of N in the wastewater from livestock farming generally renders the efficiency of the wastewater treatment. Therefore, removal of N in livestock wastewater is crucial for successful treatment. The current study was conducted to investigate the optimum conditions for partial nitrification under anaerobic condition following nitritation in TPAD-BNR(two-phase anaerobic digestion-biological nitrogen removal) operating system. Sequential operating test to stimulate partial nitrification in reactor showed that partial nitrification occurred at a ratio of 1.24 in $NO_2{^-}$-N:$NH_4{^+}$-N. With this result, a wide range of factors affecting stable nitritation were examined through regression analysis. In the livestock wastewater treatment procedure, the hydraulic retention time (HRT) and pH range for optimum nitrite accumulation in the reactor were 1-1.5 days and 7-8, respectively. It was appeared that accumulation of $NO_2{^-}$-N in the reactor is due to inhibition of the $NO_2{^-}$-N oxidizer by free ammonia (FA) while the effect of free nitrous acid was minimal. Nitrification was not influenced by DO concentration at a range of 2.0-3.0 mg/L and the difference in the growth rate between $NH_4{^+}$-N oxidizer and $NO_2{^-}$-N oxidizer was dependent on the temperature in the reactor.

• Korean Circulation Journal
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• v.52 no.10
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• pp.771-781
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• 2022

Background and Objectives: Although long QT syndrome (LQTS) is a potentially life-threatening inherited cardiac channelopathy, studies documenting the long-term clinical data of Korean patients with LQTS are scarce. Methods: This retrospective cohort study included 105 patients with LQTS (48 women; 45.7%) from a single tertiary center. The clinical outcomes were analyzed for the rate of freedom from breakthrough cardiac events (BCEs), additional treatment needed, and death. Results: LQTS was diagnosed at a median age of 11 (range, 0.003-80) years. Genetic testing was performed on 90 patients (yield, 71.1%). The proportions of genetically confirmed patients with LQTS types 1, 2, 3, and others were 34.4%, 12.2%, 12.2%, and 12.2%, respectively. In the symptomatic group (n=70), aborted cardiac arrest was observed in 30% of the patients. Treatments included medications in 60 patients (85.7%), implantable cardioverter-defibrillators in 27 (38.6%; median age, 17 years; range, 2-79 years), and left cardiac sympathetic denervation surgery in 7 (10%; median age, 13 years; range, 2-34). The 10-year BCE-free survival rate was 73.2%. By genotype, significant differences were observed in BCEs despite medication (p<0.001). The 10-year BCE-free survival rate was the highest in patients with LQTS type 1 (81.8%) and the lowest in those with multiple LQTS-associated mutations (LQTM). All patients with LQTS survived, except for one patient who had LQTM. Conclusions: Good long-term outcomes can be achieved by using recently developed genetically tailored management strategies for patients with LQTS.

• Radiation Oncology Journal
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• v.17 no.2
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• pp.120-129
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• 1999

Purpose : Serum squamous cell (SCC) antigen levels were examined in uterine cervix cancer undergoing radiation therapy, and authors analyzed the relationship between SCC antigen levels and treatment results. Materials and Methods :This is a retrospective study of 181 conical carcinoma patients who received radiotherapy and examined serial serum SCC antigen from 1991 to 1997 at Soonchunhyang University Hospital. One hundred and eighteen patients underwent SCC antigen evaluation at diagnosis The relationship between the serum tumor marker level and disease free survival, recurrence pattern, and other prognostic factors were analyzed according to various statistical methods. Results : The Positivity rate (initial serum value above 2.5 ng/ml) was increased with FIGO stage (IB-IIA 57% to IV 91%) and more discriminative than cutoff value of 1.5 ng/ml. Five year disease free survival rates for the stage IB-IIA, IIB, III and IV were 79.2%, 68.7%, 33.4% and 0%, respectively. The 5-year disease free survival rate for patients with serum SCC antigen levels above 5.0 ng/ml was 34% versus 55~62% for patients with normal range (>1.5 ng/ml) or mildly elevated levels (1.5~5.0 ng/ml). Rising SCC antigen levels preceded the clinical detection of disease by a mean of 4.8 months (range 1 ~13 months). Negative linear correlation was observed between initial SCC antigen levels and relapse free survival (r=-0.226), and by multivariate analysis, initial SCC antigen level had a large impact on the relapse free survival. Conclusion : SCC antigen assay is a useful aid to predict the prognosis of squamous cell carcinoma of the uterine cervix and to detect recurrence.

• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.331-335
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• 2012

A miniaturized laser beam transmitter, in which a visible laser module at ${\lambda}$=650 nm is precisely stacked upon an infrared (IR) module at ${\lambda}$=905 nm, has been proposed and constructed to provide an IR collimated beam in conjunction with a collinear monitoring visible beam. In particular, the IR beam is selectively dispersed through a perforated sheet diffuser, so as to create a rapidly diverging close-range beam in addition to a highly defined long-range beam simultaneously. The complementary close-range beam plays a role in mitigating the blind region in the vicinity of the transmitter, which is inevitably missed by the main long-range beam, thereby uniformly extending the transmitter's effective trajectory that is sensed by a receiver. The proposed transmitter was designed through numerical simulations and then fabricated by incorporating a diffuser sheet, perforated with an aperture of 2 mm. For the manufactured transmitter, the IR long-range beam was observed to have divergences of ~2.3 and 1.6 mrad in the fast and slow axes, respectively, while the short-range beam yielded a divergence of ~24 mrad. The angular alignment between the long-range IR and visible beams was as accurate as ~0.5 mrad. According to an outdoor feasibility test involving a receiver, the combination of the IR long- and short-range beams was proven to achieve a nearly uniform trajectory over a distance ranging up to ~600 m, with an average detectable cross-section of ${\sim}60{\times}80cm^2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.3
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• pp.220-226
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• 2002

Amorphous $Sb_{2-x}Bi_xTe_3$ (x = 0.0, 0.5 and 1.0) thin films were prepared by vacuum evaporation. The resistivity of 7he films decreases from 1.4{\times}10^{-2}$ to $8.84{\times}10^{-5}\Omega cm$ and the type of conductivity changes from p to n with the increase of the x value of the films. D.C. conduction studies on these films ate performed at various electric fields in the temperature range of 303-403 K. At low electric fields, two types of conduction mechanisms, i.e. the variable range hopping and the phonon assisted hopping are found to be responsible for the conduction, depending upon the temperature. The activation energy decreases from 0.082 to 0.076 eV in the temperature range of 303-363 K and from 0.47-0.456 eV in the second range of 363-403 K, indicating the shift of the Fermi level towards the conduction band edge and hence the change of the conduction from P to n type with the increase of the Bi concentration. Poole-Frankel emission dominates at high fields. The shape of the potential well of the localized centre is deduced and the mean free path of the charge carriers is also calculated.

• Journal of Pharmaceutical Investigation
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• v.23 no.2
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• pp.111-118
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• 1993

The hemolytic characteristics of amphotericin B-containing liposomes have been investigated in vitro. From the hemolysis of human erythrocytes against free and liposomal amphotericin B, the marked reduction in the toxicity of amphotericin B was observed by incorporating the drug in egg PC liposomes. For 45 min, free amphotericin B at $9.6\;{\mu}g/ml$ could completely lyse 2 wt% human erythrocytes. However, liposomal amphotericin B had essentially no lytic effect even in the range over $9.6\;{\mu}g/ml$. In the 66 hr-hemolysis experiment, liposomal amphotericin B showed the slowly hemolysing chracteristics during the experimental period regardless of the concentration of amphotericin B but rapid hemolysis only for 12 hr was observed in the case of free amphotericin B and the degree of hemolysis for 12 hr was maintained after that time. Also the hemolysing ability of liposomal amphotericin B at $4\;{\mu}g/ml$ was lower than that of free amphotericin B at the same concentration for 66 hr. On the other hand, the dependence of hemolysis on amphotericin B contents in egg PC liposomes was significant between 1.64 mole% amphotericin B-containing liposomes and 15.79 or 27.27 mole% amphotericin B-containing liposomes. But no marked difference in hemolysis was observed between 15.79 and 27.27 mole% amphotericin B-containing liposomes. Especially, cholesterol as an excipient in amphotericin B-containing liposomes significantly reduced the hemolysis of human erythrocyte. The degree of hemolysis in 5 mole% amphotericin B-containing liposomes was reduced to approximately 50% of value in the cholesterol-free liposomes by adding 50% cholesterol.

• Archives of Plastic Surgery
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• v.40 no.3
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• pp.226-231
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• 2013

Background The reconstruction of volar surface defects is difficult because of the special histologic nature of the tissue involved. The plantar surface is the most homologous in shape and function and could be considered the most ideal of reconstructive options in select cases of volar surface defects. In this paper, we evaluate a single institutional case series of volar tissue defects managed with second toe plantar free flaps. Methods A single-institution retrospective review was performed on 12 cases of reconstruction using a second toe plantar free flap. The mean age was 33 years (range, 9 to 54 years) with a male-to-female ratio of 5-to-1. The predominant mechanism was crush injury (8 cases) followed by amputations (3 cases) and a single case of burn injury. Half of the indications (6 cases) were for soft-tissue defects with the other half for scar contracture. Results All of the flaps survived through the follow-up period. Sensory recovery was related to the time interval between injury and reconstruction-with delayed operations portending worse outcomes. There were no postoperative complications in this series. Conclusions Flexion contracture is the key functional deficit of volar tissue defects. The second toe plantar free flap is the singular flap whose histology most closely matches those of the original volar tissue. In our experience, this flap is the superior reconstructive option within the specific indications dictated by the defect size and location.