• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.69.2-69.2
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• 2012

Graphene films have a strong potential to replace indium tin oxide anodes in organic light-emitting diodes (OLEDs), to date. However, the luminous efficiency of OLEDs with graphene anodes has been limited by a lack of efficient methods to improve the low work function and reduce the sheet resistance of graphene films to the levels required for electrodes. Here, we fabricate flexible OLEDs by modifying the graphene anode to have a high work function and low sheet resistance, and thus achieve extremely high luminous power efficiencies (37.2 lm/W in fluorescent OLEDs, 102.7 lm/W in phosphorescent OLEDs), which are significantly higher than those of optimized devices with an indium tin oxide anode (24.1 lm/W in fluorescent OLEDs, 85.6 lm/W in phosphorescent OLEDs). We also fabricate flexible white OLED lighting devices using the graphene anode. These results demonstrate the great potential of graphene anodes for use in a wide variety of high-performance flexible organic optoelectronics.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.7 no.1
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• pp.11-18
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• 1989

Observations to precise levelling nets contain different types of error because it has been caried out with various instruments and techniques, and also completed through long period. In order to establish a precise levelling nets, therefore, the weight function has to be selected adequately in the adjustment of nets. The purpose of the study is to determine a suitable weight function for the first order geodetic levelling nets in Korea and, therefore, the various numerical tests are performed with different statistical error models. The result of the study shows that the weight function, W＝1/$L^2$ is more efficient than W＝1/L in the first order levelling nets in the Korea.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.12
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• pp.1125-1131
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• 2013

Nowadays, embedded software development using the MATLAB/Simulink system is gradually emerging. Studies generating the parts of embedded S/W in a Rapid Prototype are presented. In this paper, a method to generate the entire embedded S/W of enhanced AC motor control is proposed. High performance motor control could not be achieved with the basic Simulink library and RAppID Toolbox library as it does not have PWM based Interrupt, an ASAC (Analog Sensing for AC Motors) function and other special functions of the Freescale MPC555x. Consequently, the required libraries for enhanced AC motor control are created by Legacy code tool, TLC (Target Language Compiler) and S-Function (System-Function) of MATLAB/ Simulink and utilized in the Rapid Prototype. Motor control performance and execution time are compared automatically to the generated-code S/W with the hand coded S/W. The IPMSM (Interior Permanent Magnet Synchronous Motor) and MPC5553 board that were designed as the AC motor controller for hybrid electrical vehicle are used for the test. The performances meet the requirements and satisfactory results are acquired.

• Honam Mathematical Journal
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• v.44 no.1
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• pp.135-145
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• 2022

This paper aims to investigate characterizations on parameters k₁, k₂, k₃, k₄, k₅, l₁, l₂, l₃, and l₄ to find relation between the class of 𝓗(k, l, m, n, o) hypergeometric functions defined by $$5_F_4\[{\array{k_1,\;k_2,\;k_3,\;k_4,\;k_5\\l_1,\;l_2,\;l_3,\;l_4}}\;:\;z\]=\sum\limits_{n=2}^{\infty}\frac{(k_1)_n(k_2)_n(k_3)_n(k_4)_n(k_5)_n}{(l_1)_n(l_2)_n(l_3)_n(l_4)_n(1)_n}z^n$$. We need to find k, l, m and n that lead to the necessary and sufficient condition for the function zF([W]), G = z(2 - F([W])) and $H_1[W]=z^2{\frac{d}{dz}}(ln(z)-h(z))$ to be in 𝓢^*(2^-r), r is a positive integer in the open unit disc 𝒟 = {z : |z| < 1, z ∈ ℂ} with $$h(z)=\sum\limits_{n=0}^{\infty}\frac{(k)_n(l)_n(m)_n(n)_n(1+\frac{k}{2})_n}{(\frac{k}{2})_n(1+k-l)_n(1+k-m)_n(1+k-n)_nn(1)_n}z^n$$ and $$[W]=\[{\array{k,\;1+{\frac{k}{2}},\;l,\;m,\;n\\{\frac{k}{2}},\;1+k-l,\;1+k-m,\;1+k-n}}\;:\;z\]$$.

• Journal of the Korean Society of Radiology
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• v.18 no.1
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• pp.21-26
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• 2024

The one of the famous deep learning models for object detection task is you only look once version 5 (YOLOv5) framework based on the one stage architecture. In addition, YOLOv5 model indicated high performance for accurate lesion detection using the bottleneck CSP layer and skip connection function. The purpose of this study was to evaluate the performance of YOLOv5 framework according to various hyperparameters in position emission tomogrpahy (PET) phantom images. The dataset was obtained from QIN PET segmentation challenge in 500 slices. We set the bounding box to generate ground truth dataset using labelImg software. The hyperparameters for network train were applied by changing optimization function (SDG, Adam, and AdamW), activation function (SiLU, LeakyRelu, Mish, and Hardwish), and YOLOv5 model size (nano, small, large, and xlarge). The intersection over union (IOU) method was used for performance evaluation. As a results, the condition of outstanding performance is to apply AdamW, Hardwish, and nano size for optimization function, activation function and model version, respectively. In conclusion, we confirmed the usefulness of YOLOv5 network for object detection performance in nuclear medicine images.

• Journal of the Korean Vacuum Society
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• v.5 no.4
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• pp.301-308
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• 1996

The heat of desorption and the work function change induced by nitrogen adsorption on the slepped tungstein surface plants, W(210) and W(310), are measured using the Field Electron Emission Microscope(FEM). The adsoption sites are predicted from the Thermal Desortion Spectra(TDS). The wirk function change of both W(210) and W(310) planes increase as increasing the nitrogen dose and saturates at the nitrogen dose about 5 Langmuir to 0.29 eV and 0.20 eV respectively. We find three adsorption site on each plane for the low dose range. The TDS result shows that the intensity of $\alpha_1$ state on W(310) is much stronger than that of $\alpha_1$ state on W(210), and the direction of nitrogen dipole moment adsorbed on the sites correspond to $\alpha_1$ and $\beta_2$ state on W(210) and W(310) planes are in the opposite direction to that of the equivalent states on W(100) plane. From this observation we can predict the relative atomic position in the z-direction (perpendicular direction to the surface) of nitrogen molecules/atoms adsorbed on these sites.

• Korean Journal of Mathematics
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• v.20 no.4
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• pp.371-379
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• 2012

Let D be an integral domain, $\bar{D}$ be the integral closure of D, * be a star operation of finite character on D, $*_w$ be the so-called $*_w$-operation on D induced by *, X be an indeterminate over D, $N_*=\{f{\in}D[X]{\mid}c(f)^*=D\}$, and $Kr(D,*)=\{0\}{\cup}\{\frac{f}{g}{\mid}0{\neq}f,\;g{\in}D[X]$ and there is an $0{\neq}h{\in}D[X]$ such that $(c(f)c(h))^*{\subseteq}(c(g)c(h))^*$}. In this paper, we show that D is a *-quasi-Pr$\ddot{u}$fer domain if and only if $\bar{D}[X]_{N_*}=Kr(D,*_w)$. As a corollary, we recover Fontana-Jara-Santos's result that D is a Pr$\ddot{u}$fer *-multiplication domain if and only if $D[X]_{N_*} = Kr(D,*_w)$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.711-712
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• 2009

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.157-161
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• 2000

The Eye sensitivity in the difference conditions of a light source intensity consists of two functions by the receptor of cone and rod according to a wavelength. We derived a distribution function of $P({\lambda})=A{\cdot}e^{-({\lambda}-{\lambda}_0)^2/2W^2}$ using a respond probability of the receptor of cone-rod for a photon. It was well applied for a CIE eye's sensitivity curve of a wavelength, we obtained values in case of a relative sensitivity. A = 106.4, ${\lambda}_0=559.2$, W = 83.5 for a photopic and A = 99.3 ${\lambda}_0=502.6$, W = 79.5 for a scotopic, and in case of a sensitivity curve using 1m/W units. $A=7.2{\times}10^4$, ${\lambda}_0=559.2$, W = 83.5 for a photopic and $A=1.6{\times}10^5$, ${\lambda}_0=502.6$. W = 79.5 for a scotopic.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.115-121
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• 2024

This study analyzed the influence of process variables affecting the thermodynamic equilibrium and fluid dynamics of interfaces such as reverse micelle, salt concentration, interfacial tension, and viscosity of fluids to optimize the microencapsulation process using the W1/O/W2 double emulsion method. The process variable with the greatest impact on encapsulation efficiency was found to be the difference in osmotic pressure between the W1 and W2 phases. It was observed that increasing the salt concentration in the W2 phase or decreasing the ascorbic acid concentration in the W1 phase resulted in higher encapsulation efficiency. Additionally, a larger difference in osmotic pressure led to increased damage to the surface of the microparticles, as confirmed by SEM images. The introduction of reverse micelles, which was anticipated to increase encapsulation efficiency, either had a low contribution or even decreased encapsulation efficiency. The yield of microcapsules was expressed as a universal function, applicable to all process conditions or solution compositions. According to this universal function, no further increase in yield was observed beyond the Ca (capillary number) of approximately 20.