• Journal of the Korean Mathematical Society
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• v.53 no.1
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• pp.187-199
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• 2016

The r-ary number sequences given by $$(b^{(r)}_n)_{n{\geq}0}=\Large{\frac{1}{(r-1)n+1}}(^{rn}_n)$$ are analogs of the sequence of the Catalan numbers ${\frac{1}{n+1}}(^{2n}_n)$. Their history goes back at least to Lambert [8] in 1758 and they are of considerable interest in sequential testing. Usually, the sequences are considered separately and the generalizations can go in several directions. Here we link the various r first by introducing a new combinatorial structure related to GR trees and then algebraically as well. This GR transition generalizes to give r-ary analogs of many sequences of combinatorial interest. It also lets us find infinite numbers of combinatorially defined sequences that lie between the Catalan numbers and the Ternary numbers, or more generally, between $b^{(r)}_n$ and $b^{(r+1)}_n$.

• Korean Journal of Head & Neck Oncology
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• v.8 no.2
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• pp.91-96
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• 1992

The efficacy of the fine needle aspiration biopsy and cytological examination(FNABC) under ultrasonographic(US) guides for the diagnosis of cervical tuberculous lymphadenitis was assessed. There were one hundred and one patients whose neck masses were proven to be tuberculous lymphadenites with cytologic and/or histologic diagnosis. The physical characteristics shown by US revealed that all the cases were multiple lesions. Multiregional lesions were found in 80 cases(79.1%) and 19 cases(18.8%) were the bilateral lesion. The region V was the most prevalent site(n=69, 68.3%). US findings revealed 92 cases(90.9%) showed hypoechoic lesions and 9(9.1%) showed mixed echo patterns. There was no hyperechoic lesion (p<0.05). The sensitivity of FNABC was 77.2% and specificity was 99.0%. Diagnostic accuracy was 85.0%. There was no complication during the procedures. FNABC for the diagnosis of cervical tuberculous lymphadenitis is a safe, convinient procedure and has a high specificity. The pitfall of FNABC the low sensitivity, seemed to be compensated by US evaluations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.172-182
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• 2014

In this paper, is is presented the result of design and fabrication for X band T/R module using in active array radar. The high power RF circuit was fabricated using GaN element, so that high power and high efficiency was fulfilled comparing with the previous T/R module that have under 50 W output power for X band. Designed X band T/R module demonstrated 200 W(53 dBm) peak power, 20 us pulse width with 0.4 dB pulse droop and 20 % duty cycle. And it has characteristics of 26 dB receive gain and 4.5 dB noise figure. The structure was applied to prevent serious damage of receive path and GaN HPA by transmitting power during trasmit time of a pulse radar.

• Nuclear Engineering and Technology
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• v.37 no.5
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• pp.401-422
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• 2005

We review here research and development progress achieved in US Plasma Chamber technology roughly over the last decade. In particular, we focus on two major programs carried out in the US: the APEX project (1998-2003) and the US ITER TBM activities (2003-present). The APEX project grew out of the US fusion program emphasis in the late 1990s on more fundamental science and innovation. APEX was commissioned to investigate novel technology concepts for achieving high power density and high temperature reactor coolants. In particular, the idea of liquid walls and the related research is described here, with some detailed examples of liquid metal and molten salt magnetohydrodynamic and free surface effects on flow control and heat transfer. The ongoing US ITER Test Blanket Module (TBM) program is also described, where the current first wall/blanket concepts being considered are the dual coolant lead lithium concept and the solid breeder helium cooled concepts, both using ferritic steel structures. The research described for these concepts includes both thermofluid MHD issues for the liquid metal coolant in the DCLL, and thermomechanical issues for ceramic breeder packed pebble beds in the solid breeder concept. Finally, future directions for ongoing research in these areas are described.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.12 s.103
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• pp.1179-1185
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• 2005

In this paper, novel internal antenna with its controllable resonant frequency is presented for triple-band or over mobile handsets. The operating range can include GSM(880${\~}$960 MHz), GPS(1,575$\pm$10 MHz), DCS(1,710${\~}$1,880 MHz), US-PCS(1,850${\~}$l,990 MHz), and W-CDMA(1,920${\~}$2,170 MHz). The proposed antenna is realized by combination of a half wavelength loaded line and a shorted monopole. A single shorting and feeding points are used and they are common to both antenna structures. By controlling a value of lumped inductance element between shorting point and ground plane, the antenna provides enough bandwidth to cover DCS, US-PCS, and W-CDMA respectively. When these higher bands are controlled by the values of inductance, resonant characteristics in GSM and GPS bands are maintained. In this work, maximum value of the inductor is limited within 3.3 nH to mitigate gain degradation from frequency tuning. As a result, measured maximum gain of antenna is -0.58${\~}$-0.30 dBi in the GSM band, -0.57${\~}$0.43 dBi in the GPS band and 0.38${\~}$1.15 dBi in the DCS/US-PCS/W-CDMA band. In higher band, the proposed antenna is certified that resonant frequency of about 240 MHz can be effectively controlled within gain variation of about 0.77 dB by simulation and measurement.

• The Journal of the Korea Contents Association
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• v.14 no.8
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• pp.342-364
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• 2014

The purpose of this paper is to provide an answer for the following question: What are the major shifts and implications of the unprecedently competitive and rapidly changing media ecosystem in the era of N-screen and OTT services? I've attempted to understand the complex and competitive nexus among media from an historical context by focusing on the displacement vs. complement thesis. The TPC model by Han has been employed for the analysis of the current dynamics of US media industries by triangulating three areas: Technology/industry, public policy and consumer/culture. More specifically, the US media landscape is initially divided into two competitive turfs - the competitors equipped with OTT services and the legacy media industry, and then the traditional media industry was grouped again into PayTV group(telecom service providers with IPTV and mobile TV, cable/Satellite TV networks) and Free (over-the-air) TV networks. Six major shifts were identified by the analysis: power shift in telecom carriers, power shifts in TV industry, Telecom/OTT partnership, time shifts, place shifts, and finally business model shifts.

• Communications of the Korean Mathematical Society
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• v.17 no.3
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• pp.535-540
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• 2002

Let X$_1$, X$_2$‥‥,X$\_$n/ be n independent and identically distributed random variables with continuous cumulative distribution function F(x). Let us rearrange the X's in the increasing order X$\_$1:n/ $\leq$ X$\_$2:n/ $\leq$ ‥‥ $\leq$ X$\_$n:n/. We call X$\_$k:n/ the k-th order statistic. Then X$\_$n:n/ - X$\_$n-1:n/ and X$\_$n-1:n/ are independent if and only if f(x) = 1-e(equation omitted) with some c > 0. And X$\_$j/ is an upper record value of this sequence lf X$\_$j/ > max(X$_1$, X$_2$,¨¨ ,X$\_$j-1/). We define u(n) = min(j|j > u(n-1),X$\_$j/ > X$\_$u(n-1)/, n $\geq$ 2) with u(1) = 1. Then F(x) = 1 - e(equation omitted), x > 0 if and only if E[X$\_$u(n+3)/ - X$\_$u(n)/ | X$\_$u(m)/ = y] = 3c, or E[X$\_$u(n+4)/ - X$\_$u(n)/|X$\_$u(m)/ = y] = 4c, n m+1.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.4
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• pp.247-252
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• 2009

This paper presents an Integer-N phase-locked loop (PLL) frequency synthesizer using a novel prescaler based on a charge pump and clock triggering circuit. A quadrature VCO has been designed for the 900MHz UHF RFID application. In this circuit, a voltage-controlled oscillator(VCO), a novel Prescaler, phase frequency detector(PFD), charge pump(CP), and analog lock detector(ALD) have been integrated with 0.35-${\mu}m$CMOS process. The integer divider has been developed with a verilog-HDL module, and the PLL mixed mode simulation has been performed with Spectre-Verilog co-simulator. The sweep range of VCO is designed from 828 to 960 MHz and the VCO generates four phase quadrature signals. The simulation results show that the phase noise of VCO is -102dBc/Hz at 100 KHz offset frequency, and the maximum lock-in time is about 4us with 32MHz step change (from 896 to 928 MHz).

• Journal of Environmental Health Sciences
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• v.50 no.4
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• pp.267-273
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• 2024

Background: During the coronavirus pandemic, masks played a critical role in preventing respiratory infections. While the performance of masks such as KF-certified masks and N95 masks was evaluated and managed by the authorities, the performance of common masks was not. Objectives: This study aimed to evaluate the performance of uncertified masks in four Asian countries against certification standards (Korean KF80, KF94, and US N95). Methods: Thirty uncertified mask products from Indonesia, 20 from South Korea, 26 from Taiwan, and 30 from Thailand were purchased to perform performance evaluations. The uncertified masks included disposable dental masks, cloth masks, and children's masks. Filtration efficiency and inhalation airflow resistance tests were conducted according to Korean KF80, KF94, and US N95 protocols. Results: None of the 106 identified masks complied with the KF94 standard. A few complied with the KF80 standard: four from Indonesia, four from South Korea, 13 from Taiwan, and 16 from Thailand. Some of the masks met the N95 standard: one from Indonesia, three from South Korea, two from Taiwan, and one from Thailand. Conclusions: Since many uncertified masks did not comply with performance standards, wearing them might not have provided sufficient protection. Performance of uncertified masks could provide critical information for next pandemic management.

• Journal of applied mathematics & informatics
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• v.34 no.3_4
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• pp.207-220
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• 2016

Our goal is to construct a two-frequency-dependent formula $I_N$ which interpolates a product f of two functions with different frequencies at some N points. In the beginning, it is not clear to us that the formula $I_N$ satisfies $I_N=f$ at the points. However, it is later shown that $I_N$ satisfies the above equation. For this theoretical development, a one-frequency-dependent formula is introduced, and some of its characteristics are explained. Finally, our newly constructed formula $I_N$ is compared to the classical Lagrange interpolating polynomial and the one-frequency-dependent formula in order to show the advantage that is obtained by generating the formula depending on two frequencies.