• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.523-532
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• 2008

In this paper, we proposed a U-shaped RFID tag antenna with isotropic radiation characteristic for the stable operation of RFID system. The proposed antenna is composed of a U-shaped half wavelength dipole and a rectangular-shaped feed. In order to have good impedance matching with a tag chip, the commercial tag chip is attached to the lower center of the feed. A gain deviation characteristic of the U-shaped tag antenna can be further improved by inserting a rectangular slit in the lower center of the U-shaped antenna body. On the condition of VSWR<2, the tag antennas of two structures satisfy the Korea UHF RFID bandwidth and showed the gain deviation of less than 1.63 dB and 0.74 dB for without slit and with slit, respectively. On the condition of VSWR<5.8, the U-shaped tag antenna showed the gain deviation of less than 3.8 dB and 1.2 dB for without slit and with slit, respectively.

• Korean Journal of Radiology
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• v.22 no.3
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• pp.476-488
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• 2021

Objective: We aimed to develop a deep neural network for segmenting lung parenchyma with extensive pathological conditions on non-contrast chest computed tomography (CT) images. Materials and Methods: Thin-section non-contrast chest CT images from 203 patients (115 males, 88 females; age range, 31-89 years) between January 2017 and May 2017 were included in the study, of which 150 cases had extensive lung parenchymal disease involving more than 40% of the parenchymal area. Parenchymal diseases included interstitial lung disease (ILD), emphysema, nontuberculous mycobacterial lung disease, tuberculous destroyed lung, pneumonia, lung cancer, and other diseases. Five experienced radiologists manually drew the margin of the lungs, slice by slice, on CT images. The dataset used to develop the network consisted of 157 cases for training, 20 cases for development, and 26 cases for internal validation. Two-dimensional (2D) U-Net and three-dimensional (3D) U-Net models were used for the task. The network was trained to segment the lung parenchyma as a whole and segment the right and left lung separately. The University Hospitals of Geneva ILD dataset, which contained high-resolution CT images of ILD, was used for external validation. Results: The Dice similarity coefficients for internal validation were 99.6 ± 0.3% (2D U-Net whole lung model), 99.5 ± 0.3% (2D U-Net separate lung model), 99.4 ± 0.5% (3D U-Net whole lung model), and 99.4 ± 0.5% (3D U-Net separate lung model). The Dice similarity coefficients for the external validation dataset were 98.4 ± 1.0% (2D U-Net whole lung model) and 98.4 ± 1.0% (2D U-Net separate lung model). In 31 cases, where the extent of ILD was larger than 75% of the lung parenchymal area, the Dice similarity coefficients were 97.9 ± 1.3% (2D U-Net whole lung model) and 98.0 ± 1.2% (2D U-Net separate lung model). Conclusion: The deep neural network achieved excellent performance in automatically delineating the boundaries of lung parenchyma with extensive pathological conditions on non-contrast chest CT images.

• Journal of Korea Technology Innovation Society
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• v.7 no.2
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• pp.257-281
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• 2004

In this paper we： (1) analyze the relationship among public R＆D investment, private R＆D investment, and GDP by employing the Clangor causality test; (2) examine if there is any country-specific pattern in the relationship by testing the cases of Korea, the U.S. and Japan. We found some common results for the above countries as follows： (i) GDP causes Public R＆D, not vice versa; (ii) Private R＆D causes GDP; and (iii) Public R＆D does not cause Private R＆D. For the bivariate model of GDP and total R＆D, the results show the existence of one-way causality running from total R＆D to GDP f3r both U.S. and Japan. We also found bidirectional causal relationship between GDP and total R＆D for Korea, which could be interpreted as a typical pattern for newly industrialized countries.

• Journal of the Korean Mathematical Society
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• v.51 no.1
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• pp.67-86
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• 2014

Based on an expanded mixed finite element method, we consider the semidiscrete approximations of the solution u of the quasilinear pseudo-parabolic equation defined on ${\Omega}{\subset}R^d$, $1{\leq}d{\leq}3$. We construct the semidiscrete approximations of ${\nabla}u$ and $a(u){\nabla}u+b(u){\nabla}u_t$ as well as u and prove the existence of the semidiscrete approximations. And also we prove the optimal convergence of ${\nabla}u$ and $a(u){\nabla}u+b(u){\nabla}u_t$ as well as u in $L^2$ normed space.

• The Journal of the Acoustical Society of Korea
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• v.29 no.8
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• pp.491-496
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• 2010

Thermoacoustic power generation by a spiral heater in the Rijke tube was analyzed numerically. In the analysis, variables were normalized by the angular frequency of the sound and the thermal diffusivity of the air. The effect of the heater wire diameter d, the spacing between wires P-d, and the air-current velocity $U_0$, upon the power generation was obtained and discussed. When the spacing is broad enough, the normalized velocity is $U_0{\approx}0.8$ and the diameter is $d{\approx}4$ for the maximum power generation. With decrease of the spacing, however, the power generation increases more than 5 times and becomes maximum around $d{\approx}2$, $P-d{\approx}3$. And the velocity $U_0{\approx}0.8$ for the maximum power generation is almost independent of the wire spacing.

• Journal of Korean Medicine Rehabilitation
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• v.24 no.3
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• pp.29-37
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• 2014

Objectives Osteoporosis is an impending problem in the rapidly aging society. The purpose of this study is to identify the effects of Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) on osteoporosis induced by ovariectomy in rats. Methods 24 rats were randomly assigned to a SHAM group, a control group, and a Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) group (n=8). Ovaries were extracted and for 8 weeks, the rats were given dry feeds and Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) group were given a mixture of dry feeds and Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$). At 8 weeks, their body weight, femur mass, tibia ash per body ratio, overall surface area and thickness of the trabeculae, overall surface area of the osteoblasts, and the number of osteoclasts were measured and levels of albumin, aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), total-cholesterol, calcium and estradiol were recorded. Results There was no significant difference in the weight of the femur and the tibia ash per body ratio. The Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) group had significantly thicker trabeculae than the control group and showed a minimal increase of overall surface area of the trabeculae. The overall surface area of the osteoblasts and the number of osteoclasts decreased in the Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) group. There were no statistically significant differences in AST, ALT, ALP, total cholesterol, phosphorus, and estradiol levels. On the contrary the Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) group had significantly higher levels of Albumin, triglyceride, and calcium. Conclusions It can be concluded that oral intake of Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) prevents the thinning process of the trabeculae. Thus, it may have positive effects on the treatment and prevention of osteoporosis in postmenopausal women.

• Journal of the Korea Society of Computer and Information
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• v.19 no.2
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• pp.161-171
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• 2014

In this paper the flow dynamics of the flue gas equipment in the desulfurization system was numerically analyzed by simulating the problems for the turbulent and combustion flow from Induced Draft Fan(I.D.Fan) outlet to Booster Up Fan(B.U.Fan) inlet using the commercial CFD software of CFD-ACE+ in CFDRC company for Computational Fluid Dynamic Analysis. The guide vane of this section was examined for the minimum pressure loss and the uniform flow dynamic to B.U.Fan with the proper velocity from I.D,Fan exit to B,U,Fan inlet section at the boiler both the maximum continuous rating and the design base. The guide vanes at I,D.Fan outlet and B.U.Fan inlet were removed and modified by numerical simulation of the CFD analysis. The flue gas at the system had the less pressure loss and the uniform flow dynamics of the flow velocity and flow line by comparing with the old design equipment.

• Journal of the Korean Applied Science and Technology
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• v.10 no.2
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• pp.11-18
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• 1993

Contents of vitamin $D_3$ and 25-OH-vitamin $D_3$ in marine animal products(20 species) were determined by HPLC. The isomers of vitamin D, $D_2$ and $D_3$, were not clearly separated on a reversed phase, ${\mu}$ Bonda Pak, with 20% methanol-acetonitrile, and on a normal phase, Zorbax SIL. with 0.4% isopropanol-hexane, but 25-OH-vitamin $D_2$ and-$D_3$ were separated on either ${\mu}$ Bonda Pak with 10% methanol-acetonitrile, or on Zorbax SIL with 2.2% isopropanol-hexane, respectively. Although levels of vitamin $D_3$ and 25-OH-vitamin $D_3$ varied remarkably according to species, their average value(fish : $l,l87{sim}36,007$ I.U/sample 100g, mussel : $58{\sim}1,706$ I.U/sample 100g, pickle: $1,208{\sim}79,358$ I.U/sample 100g) was greatly higher than that of meat($80{\sim}100$ I.U/sample 100g) and dairy products($400{\sim}800$ I.U/sample 100g). Fatty tissues of fish and pickled fish intestines contained high level of vitamin $D_3$ and 25-OH-vitamin $D_3$, while the clam and mussel known to have various kinds of sterol including ${\Delta}^7$-sterol showed very low levels of vitamin $D_3$ and its derivative.

• Journal of environmental and Sanitary engineering
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• v.18 no.1
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• pp.30-40
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• 2003

The study subjects included the workers who were estimated to have been exposed in a low density of lead-laden glaze from pottery manufacturers. They were evaluated in terms of PbB and PbU as indices of lead concentration in the body, and Hb, Hct, ALAD, and FEP as indices of biochemical lead poisoning. Consequently, the study results revealed the relationship between each of indices and its effectiveness to indicate the degree of occupational lead exposure. 1. The mean of PbB was $22.85{\;}{\mu}g/d{\ell}$(range; $4.2~44.7{\;}{\mu}g/d{\ell}$) and PbU $45.69{\mu}g/d{\ell}$(range; $6.7~87.5{\mu}g/d{\ell}$), to indicate the level of lead exposure in the subjects. 2. While there was a high, linear correlation between PbB, PbU and FEP (r=0.835, r=0.855, respectively), a low correlation existed between PbB and ALAD(r=-0.240). 3. While there was a high, linear correlation between PbU and FEP(r=0.825), a low correlation existed between PbU and ALAD(r=-0.352). The above results suggest that FEP can be used as a highly useful biochemical index of lead poisoning, based on its high correlation with PbB and PbU indicating lead concentration in the body.

• Communications of the Korean Mathematical Society
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• v.34 no.1
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• pp.185-202
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• 2019

In this paper, we investigate many types of stability, like (uniform stability, exponential stability and h-stability) of the first order dynamic equations of the form $$\{u^{\Delta}(t)=Au(t)+f(t),\;\;t{\in}{\mathbb{T}},\;t>t_0\\u(t_0)=x{\in}D(A),$$ and $$\{u^{\Delta}(t)=Au(t)+f(t,u),\;\;t{\in}{\mathbb{T}},\;t>t_0\\u(t_0)=x{\in}D(A),$$ in terms of the stability of the homogeneous equation $$\{u^{\Delta}(t)=Au(t),\;\;t{\in}{\mathbb{T}},\;t>t_0\\u(t_0)=x{\in}D(A),$$ where f is rd-continuous in $t{\in}{\mathbb{T}}$ and with values in a Banach space X, with f(t, 0) = 0, and A is the generator of a $C_0$-semigroup $\{T(t):t{\in}{\mathbb{T}}\}{\subset}L(X)$, the space of all bounded linear operators from X into itself. Here D(A) is the domain of A and ${\mathbb{T}}{\subseteq}{\mathbb{R}}^{{\geq}0}$ is a time scale which is an additive semigroup with property that $a-b{\in}{\mathbb{T}}$ for any $a,b{\in}{\mathbb{T}}$ such that a > b. Finally, we give illustrative examples.