• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_1
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• pp.277-285
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• 2024

Hydrogen is considered a key energy source to achieve carbon neutrality through the global goal of 'net zero'. Due to limitations in producing green hydrogen domestically, Korean companies are interested in importing green hydrogen produced overseas. The Middle East has high-quality solar energy resources and is attracting attention as a region producing green hydrogen using renewable energy. To build a green ammonia plant, optimization of the production facility configuration and economic feasibility analysis are required. It is expected that it will contribute to reviewing the economic feasibility of constructing overseas hydrogen production plants through preliminary economic feasibility analysis.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.2
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• pp.30-39
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• 2009

Extraction of glomeruli region plays a very important role for diagnosing nephritis automatically. However, it is not easy to extract glomeruli region correctly because the difference between glomeruli region and other region is not obvious, simultaneously unevennesses that is brought in the sampling process and in the imaging process. In this study, a new method for extracting renal glomeruli region using genetic algorithm is proposed. The first, low and high resolution images are obtained by using Laplacian-Gaussian filter with ${\sigma}=2.1$ and ${\sigma}=1.8$, then, binary images by setting the threshold value to zero are obtained. And then border edge is detected from low resolution images, the border of glomeruli is expressed by a closed B-splines' curve line. The parameters that decide the closed curve line with this low resolution image prevent the noises and the border lines from breaking off in the middle by searching using genetic algorithm. Next, in order to obtain more precise border edges of glomeruli, the number of node points is increased and corrected in order from eight to sixteen and thirty two from high resolution images. Finally, the validity of this proposed method is shown to be effective by applying to the real images.

• Journal of Astronomy and Space Sciences
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• v.27 no.4
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• pp.329-335
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• 2010

We investigate the sources of the variation of the high-latitude thermospheric neutral mass density depending on the interplanetary magnetic field (IMF) conditions. For this purpose, we have carried out the National Center for Atmospheric Research Thermosphere-Ionosphere Electrodynamics General Circulation Model (NCAR-TIEGCM) simulations for various IMF conditions under summer condition in the southern hemisphere. The NCAR-TIEGCM is combined with a new empirical model that provides a forcing to the thermosphere in high latitudes. The difference of the high-latitude thermospheric neutral mass density (subtraction of the values for zero IMF condition from the values for non-zero IMF conditions) shows a dependence on the IMF condition: For negative $B_y$ condition, there are significantly enhanced difference densities in the dusk sector and around midnight. Under the positive-$B_y$ condition, there is a decrease in the early morning hours including the dawn side poleward of $-70^{\circ}$. For negative $B_z$, the difference of the thermospheric densities shows a strong enhancement in the cusp region and around midnight, but decreases in the dawn sector. In the dusk sector, those values are relatively larger than those in the dawn sector. The density difference under positive-$B_z$ condition shows decreases generally. The density difference is more significant under negative-$B_z$ condition than under positive-$B_z$ condition. The dependence of the density difference on the IMF conditions in high latitudes, especially, in the dawn and dusk sectors can be explained by the effect of thermospheric winds that are associated with the ionospheric convection and vary following the direction of the IMF. In auroral and cusp regions, heating of thermosphere by ionospheric currents and/or auroral particle precipitation can be also the source of the dependence of the density difference on the IMF conditions.

• Korean Journal of Applied Biomechanics
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• v.30 no.1
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• pp.7-16
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• 2020

Objective: It is to find factors related to stability through analysis of plantar pressure factors according to the level of instability when performing Snatch. Method: Foot pressure analysis was performed while 10 weightlifters performed 80% of the highest level of Snatch, and motion was classified and analyzed in 3 grades according to the level of instability. Results: First, in Bad Motion, the movement distance of the pressure center in the direction of ML and AP was larger significantly in Phase 2. Second, in Phase 2, the number of zero-crossing in the AP direction was larger statistically significantly in Good Motion. Third, in the bad motion in Phase 3, the number of zero-crossing in the ML direction showed a significantly larger value. Fourth, in Phase 4, it was found that the more stable the lock out motion, the greater the activity of foot controlling in the left and right directions. Fifth, Phase 3, the greater the Maximum/Mean foot pressure value, the more stable the pulling action. Sixth, in Phase 2, the foot pressure was concentrated with a wide distribution in the midfoot and rearfoot. Seventh, the triggering number of the forefoot region was small in the last pull phase. Eighth, the number of triggers in the toe area was significantly higher during Good Motion in Phase 4. Conclusion: Summarizing the factors of instability in Snatch, there was no significant difference in Phase 1 for each condition. In order to enhance the stability in Phase 2, the sensory control ability in the AP direction is required, and focusing the foot pressing motion with a wide distribution in the middle and rear parts increases the instability. In Phase 3, it was found that the more unstable, the more sensory control activity was performed in the ML direction, the stronger the forefoot pressing action should be performed for a stable Snatch. In Phase 4, It is important that the feet sensory control activity in ML directions and the control ability of the toes in order to have stable Lock out motion.

• Korean Journal of Materials Research
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• v.23 no.6
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• pp.329-333
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• 2013

The structural phase transformations of $0.7Pb(Mg_{1/3}Nb_{2/3})O_3-0.3PbTiO_3$ (PMN-0.3PT) were studied using high resolution x-ray diffraction (HRXRD) as a function of temperature and electric field. A phase transformational sequence of cubic (C)${\rightarrow}$tetragonal (T)${\rightarrow}$rhombohedral (R) phase was observed in zero-field-cooled conditions; and a $C{\rightarrow}T{\rightarrow}$monoclinic $(M_C){\rightarrow}$ monoclinic ($M_A$) phase was observed in the field-cooled conditions. The transformation of T to $M_A$ phase was realized through an intermediate $M_C$ phase. The results also represent conclusive and direct evidence of a $M_C$ to $M_A$ phase transformation in field-cooled conditions. Beginning from the zero-field-cooled condition, a $R{\rightarrow}M_A{\rightarrow}M_C{\rightarrow}T$ phase transformational sequence was found with an increasing electric field at a fixed temperature. Upon removal of the field, the $M_A$ phase was stable at room temperature. With increasing the field, the transformation temperature from T to $M_C$ and from $M_C$ to $M_A$ phase decreased, and the phase stability ranges of both T and $M_C$ phases increased. Upon removal of the field, the phase transformation from R to $M_A$ phase was irreversible, but from $M_A$ to $M_C$ was reversible, which means that $M_A$ is the dominant phase under the electric field. In the M phase region, the results confirmed that lattice parameters and tilt angles were weakly temperature dependent over the range of investigated temperatures.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.1 no.3
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• pp.97-103
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• 2008

In this paper, $256{\times}256$ input image is classified into a validity block and an edge block of $8{\times}8$ block for image compression. DCT(Discrete Cosine Transform) is executed only for the DC coefficient that is validity coefficients for a validity block. Predict the position where a quantization coefficient becomes 0 for an edge block, I propose new algorithm to execute DCT in the reduced region. Not only this algorithm that I proposed reduces computational complexity of FDCT(Forward DCT) and IDCT(Inverse DCT) and decreases encoding time and decoding time. I let compressibility increase by accomplishing other stability verticality zigzag scan by the block size that was classified for each block at the time of huffman encoding each. In addition, the algorithm that I suggested reduces Run-Length by accomplishing the level verticality zigzag scan that is good for a classified block characteristic and, I offer the compressibility that improved thereby.

• International Journal of Computer Science & Network Security
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• v.21 no.2
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• pp.120-130
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• 2021

The spinal cord or CSF surgery is a very complex process. It requires continuous pre and post-surgery evaluation to have a better ability to diagnose the disease. To detect automatically the suspected areas of tumors and symptoms of CSF leakage during the development of the tumor inside of the brain. We propose a new method based on using computer software that generates statistical results through data gathered during surgeries and operations. We performed statistical computation and data collection through the Google Source for the UK National Cancer Database. The purpose of this study is to address the above problems related to the accuracy of missing hybrid KNN values and finding the distance of tumor in terms of brain cancer or CSF images. This research aims to create a framework that can classify the damaged area of cancer or tumors using high-dimensional image segmentation and Laplace transformation method. A high-dimensional image segmentation method is implemented by software modelling techniques with measures the width, percentage, and size of cells within the brain, as well as enhance the efficiency of the hybrid KNN algorithm and Laplace transformation make it deal the non-zero values in terms of missing values form with the using of Frobenius Matrix for deal the space into non-zero values. Our proposed algorithm takes the longest values of KNN (K = 1-100), which is successfully demonstrated in a 4-dimensional modulation method that monitors the lighting field that can be used in the field of light emission. Conclusion: This approach dramatically improves the efficiency of hybrid KNN method and the detection of tumor region using 4-D segmentation method. The simulation results verified the performance of the proposed method is improved by 92% sensitivity of 60% specificity and 70.50% accuracy respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.4
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• pp.215-228
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• 1991

In the East Sea of Korea the vertical structure functions of the temperature field were evaluated and the characteristic thermal zone was classified by the use of the empirical orthogonal function(EOF) method. The East Sea of Korea within the hydrographic lines of 10-107 of the Fisheries Research and Development Agency of Korea(FRDA) can be divided into three thermal regions by the characteristics of the vertical temperature variability. They are the North Korean Cold Current(NKCC) region near the coast which extends parallel to the north-south direction, the Warm-Core(WC) region which dominates almost all the hydrographic stations of the Line 104 of the FRDA and occupies a few stations of the Line-103 and -105 with its axis at the Line 104, and the East Korea Warm Current(EKWC) region which is bisected into the northern and the southern part by the WC region, respectively. Considering the two most important modes, $85.20-98.20\%$ of the total variance of temperature variation are explained in the NKCC region, $85.20-92.90\%$ in the EKWC region, and$85.50-91.70\%$ in the WC region. The first mode has its peak value at the surface with the annual cycle of variation. The spatial pattern of the first mode portrays a coherent vertical variation in the EKWC region and a clear anti-correlation both in the NKCC region and in the WC region where the zero-crossing depths are loom and 200m, respectively. The second mode of the NKCC region is particularly noticeable, haying its peak at loom with coherent vertical variation. To study the time dependency of the vertical structure functions, the extended EOF(EEOF) method was used. The persistence of the first mode is less than 4 months in the study area. The annual variation of the first mode in the NKCC region is different from those in the WC region and in the EKWC region.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.214-220
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• 2017

The spherical Al/RDX/AP composites with an average size of $550{\mu}m$ were successfully prepared by drowning-out/agglomeration (D/A) process. The surface morphology and dispersion of Al particles of those composites were investigated using SEM and EDS (energy dispersive spectrometry). As a result of thermal analysis, the onset temperature of thermal decomposition of the Al/RDX/AP composites by the D/A process was found to decrease about $50^{\circ}C$ and their thermal stability was shown to be relatively enhanced due to the increase of activation energy compared to those of using the physical mixing method. In the first decomposition region of AP, Prout-Tompkins model was shown to describe well the thermal decomposition of both composites by the physical mixing and D/A process. On the other hand, in the second decomposition region of AP, the decomposition mechanisms of composites by the physical mixing and D/A process were explained by the zero-order and contracting volume model, respectively.

• Polymer(Korea)
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• v.37 no.6
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• pp.744-752
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• 2013

The miscibility between poly(L-lactide) (PLLA) and poly(methyl methacrylate) (PMMA) was investigated using thermal analyses for the purpose of developing birefringence-free material at oriented state. The effect of methyl acrylate (MA) units as comonomer of PMMA on the miscibility was also studied. All the blends prepared in this study show composition-dependent single $T_g$'s between those of blend components and high transparency over the visible region, indicating the miscibility at molecular level and no discernible effect of MA units on it. No phase separation was observed at elevated temperature of $280^{\circ}C$, higher than the degradation of PLLA and PMMA. The interaction energy density in PLLA/PMMA blends with 17 mol% of MA was measured to be $-0.74J/cm^3$ from the equilibrium melting temperature depression based on the Hoffman-Weeks method. The blends show zero-${\Delta}$n behavior at a specific mixing ratio and the drawing ratio of 3 due to compensation of intrinsic orientation birefringence. Birefringence dispersion of PLLA/PMMA5 blends was also measured to examine the possibility for quarter-wave plates or polarizer protective films.