• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.4
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• pp.423-428
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• 2015

To identify locations and causes of interference among parts of an indoor air-conditioning unit, a 3D tolerance analysis was performed and optimized with respect to assembly gaps and the tolerance of each part. The maximum value of the defect rate resulting from the tolerance analysis was found to be 72.6 at the assembly portion of the body and drain. The maximum displacement caused by the thermal deformation during a heating operation was calculated to be approximately 1 mm by using finite element analysis (FEA). Therefore, it is possible that an interference among the assembled parts occurs. The tolerance of the drain was modified by the results of the sensitivity analysis. As a result, the defect rate was greatly reduced to 0.03. Through the FEA results of the indoor air-conditioning unit, it was shown that the improved tolerance of the drain decreased the interference among the assembled parts even though thermal deformation occurs during operation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.1-6
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• 2021

In this paper, in order to mitigate ISI(inter-symbol interference) in a diffusion-based molecular communication channel, an ISI Hamming code is proposed in which ISI characteristics are applied to a channel decoding algorithm. In order to prove the bit error rate performance of the proposed channel code, the bit error rate performance of the major channel codes applied to the molecular communication channel with ISI was compared and analyzed through simulation. From the simulation results, it can be seen that the bit error rate performance of the ISI Hamming code is the best when the number of radiated molecules is less than or equal to 1100. In addition, when the number of transmitted molecules is M=1000, the decoding method of the ISI Hamming code proposed in this paper has improved the bit error rate of approximately 5.9×10-5 compared to the Hamming code using only soft values. Compared with the ISI-mitigating channel code, which is effective for removing ISI in the molecular communication channel, the ISI Hamming code proposed in this paper is the most advantageous in a channel environment where the number of transmitted molecules is not big (M<1100). And we can see that the ISI-mitigating channel code is more advantageous when the number of transmitted molecules is large(M>1100).

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.138-143
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• 2011

To investigate the electromagnetic interference shielding efficiency (EMI SE) property based on heat treatment effects of carbon fibers in various temperatures, the polyacrilonitrle-based carbon fibers were prepared by electrospinning method and treated at 1073, 1323, 1873 and 2573 K. The surface morphology of carbon fibers was investigated by using FE-SEM and the carbon crystallization was studied by Raman spectroscopy based on effects of reaction temperatures. The electrical conductivity was obtained by measuring the surface resistance with four probe method on carbon crystallization. The permittivity, permeability and EMI SE were investigated by using S-parameter in the range of 800~4500 MHz. In case of carbon fibers treated at 2573 K, the improved carbon crystallization was confirmed by Raman spectrum and the enhanced electrical conductivity showing 54.7 S/cm was also observed. The permittivity was dramatically improved by factor of 4 based on effect of high reaction temperature. Eventually, the highly improved EMI SE value was obtained showing around 41.7 dB.

• Korean Journal of Radiology
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• v.25 no.8
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• pp.742-748
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• 2024

Objective: ¹⁸F-N-(2-(Diethylamino)ethyl)-5-(2-(2-(2-fluoroethoxy)ethoxy)ethoxy) picolinamide (¹⁸F-PFPN) is a novel positron emission tomography (PET) probe designed to specifically targets melanin. This study aimed to evaluate the diagnostic feasibility of ¹⁸F-PFPN in patients with ocular or orbital melanoma. Materials and Methods: Three patients with pathologically confirmed ocular or orbital melanoma (one male, two females; age 41-59 years) were retrospectively reviewed. Each patient underwent comprehensive ¹⁸F-PFPN and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET scans. The maximum standardized uptake value (SUV_max) of the lesion and the interference caused by background tissue were compared between ¹⁸F-PFPN and ¹⁸F-FDG PET imaging. In addition, the effect of intrinsic pigments in the uvea and retina on the interpretation of the results was examined. The contralateral non-tumorous eye of each patient served as a control. Results: All primary tumors (3/3) were detected using ¹⁸F-PFPN PET, while only two primary tumors were detected using ¹⁸F-FDG PET. Within each lesion, the SUV_max of ¹⁸F-PFPN was 2.6 to 8.3 times higher than that of ¹⁸F-FDG. Regarding the quality of PET imaging, the physiological uptake of ¹⁸F-FDG PET in the brain and periocular tissues limited the imaging of tumors. However, ¹⁸F-PFPN PET minimized this interference. Notably, intrinsic pigments in the uvea and retina did not cause abnormal concentrations of ¹⁸F-PFPN, as no anomalous uptake of ¹⁸F-PFPN was detected in the healthy contralateral eyes. Conclusion: Compared to ¹⁸F-FDG, ¹⁸F-PFPN demonstrated higher detection rates for ocular and orbital melanomas with minimal interference from surrounding tissues. This suggests that ¹⁸F-PFPN could be a promising clinical diagnostic tool for distinguishing malignant melanoma from benign pigmentation in ocular and orbital melanomas.

• Journal of Powder Materials
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• v.9 no.5
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• pp.359-364
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• 2002

We report the structure, thermal and magnetic properties of a non-equilibrium $Al_{0.6}(Fe_{50}Cu_{50})_{0.4}$ alloy powder produced by rod milling and chemical leaching. An X-ray diffractometry(XRD), a transmission electron microscope(TEM), a differential scanning calorimeter(DSC), a vibrating sample magnetometer(VSM), and superconducting quantum interference device(SQUID) were utilized to characterize the as-milled and leaching specimens. The crystallite size reached a value of about 8.82 nm. In the DSC experiment, the peak temperatures and crystallization temperatures decreased with increasing milling time. The activation energy of crystallization is 200.5 kJ/mole for as-milled alloy powder. The intensities of the XRD peaks of as-milled powders associated with the bcc type $Al_{0.5}Fe_{0.5}$ structure formative at $350^{\circ}C$ sharply increase with increasing annealing temperature. Above $400^{\circ}C$, peaks alloted to $Al_{0.5}Fe_{0.5}$ and $Al_{5}Fe_{2}$ are observed. After annealing at $600^{\circ}C$ for 1h, the leached Ll specimen transformed into bcc $\alpha$-Fe and fcc Cu phases, accompanied by a change in the structural and magnetic properties. The saturation magnetization decreased with increasing milling time, and a value of about 8.42 emu/g was reached at 500 h of milling. The coercivity reached a maximum value of about 142.7 Oe after 500 h of milling. The magnetization of leached specimens as function of fields were higher at 5 K, and increased more sharply at 5 K than at 100 K.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11A
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• pp.1087-1094
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• 2008

In this paper, we propose the acquisition method of the Cyclic-Prefix CDMA using Good-Autocorrelation-Sequence (GAS-CP-CDMA) system. The sequences for GAS-CP-CDMA are m-sequence and constant amplitude zero autocorrelation code (CAZAC) with good autocorrelation property. The GAS-CP-CDMA system is proposed for interference cancellation in multi-user and -path environment in co-cell. However, the reliable initial acquisition in multi-path fading channel and multi-user system environment is crucial. In this paper, non-coherent power detector and threshold value are used for discriminating signal acquisition. The sequence used for computer simulation is CAZAC. The simulation results show proper threshold value depends on the number of users. Through the computer simulation, we draw setting up method of the optimum threshold value for the GAS-CP-CDMA system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.127-133
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• 2013

This paper compare the performance of CCA (Compact Constellation Algorithm) adaptive equalization algorithm by effect of the compact slice weighting value for minimization of the intersymbol interference in the communication channel. The CCA combines the conventional DDA and RCA algorithm, it uses the constant modulus of the transmission signal and the considering the output of decision device by the power of compact slice weighting value in order to improving the initial convergence characteristics and the equalization noise by misadjustment in the steady state. In this process, it is confirmed by computer simulation that the compact slice weight affects the performance of CCA adaptive equalization algorithm. The performance index includes the output signal constellation, the residual isi and maximum distortion and MSE that is for the convergence characteristics, the SER according to the signal and noise power ratio at the channel is used. As a result of computer, it shows that the large weighting value gives more good in every performance index. But in SER performance, it is known that the small values gives more good in low SNR and the large values gives more good in high SNR.

• Journal of Korean Society of Rural Planning
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• v.20 no.4
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• pp.13-24
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• 2014

The pond wetlands in agricultural landscape are important natural resources that carry out the function of bio-diversity conservation. However, recently, those have been gradually embedded as their utility value were disappeared. And, the assessment methods used for pond wetlands are insufficient. Therefore, this study was conducted to examine the conservation value of pond wetlands by using the modified RAM, and present the improvement of assesment methods. The study sites, a total of 32 pond of 4 types by land use, were selected on the basis of Ramsar Convention. Through the analysis of precedent studies, the weighted 8 functions were adjusted. According to the assessment results, pond wetlands made the largest contribution to Fishery and Herpetile Habitat function. In addition, it also made large contribution to Floral Diversity, Wildlife Habitat, and Water Quality Protection function. On the other hand, it made a small contribution to Aesthetics and Recreation, Runoff Attenuation, Shoreline /Stream Bank Protection, and Flood/Storm Water Storage function due to the characteristics of small-scale pond wetlands. In the assessment of 8 functions, house type showed the worst assessment result, and mountain type showed the best assessment result. It is thought that those are due to land use type in terms of vicinity. 10 items among 52 of the modified RAM showed the same assessment results in all land use types. Accordingly, it is required to be deleted and modified the assessment method. On the other hand, it is required to add age, interference, and water use to the assessment method. It is thought that these results can be utilized for the development and modification of assessment methods focused on pond wetlands in rural area.

• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.187-190
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• 2010

$Sn_{0.99}{^{57}Fe}_{0.01}O_2$ prepared by a sol-gel method, and studied by x-ray diffractometer, vibrating magnetometer, Superconducting quantum interference devices and M$\ddot{o}$ssbauer spectroscopy. the crystal structure were found to be a rutile tetragonal structure with space group $P4_2$/mnm, and oxygen deficiency are 5.6 % by Rietveld refinement. magnetization value were $M_s=1.95{\times}10^{-2}{\mu}_B/Fe$ at room temperature, and Curri-weiss temperature were and ${\theta}_{cw}$ = 18 k, measurement of VSM and SQUID, respectively. Mssbauer spectra of $Sn_{0.99}{^{57}Fe}_{0.01}O_2$ have been Sextet taken at various temperatures ranging from 4.2 K to RT, and isomer shift value $\delta$ = 0.18~0.36 mm/s of $^{57}Fe$ ion site all of the temperature range the state shows ferric.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.1
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• pp.72-79
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• 2009

This paper describes the performance evaluation of NHD(nonhomogeneity detector) for STAP(space-time adaptive processing) airborne radar according to various normalization methods in the nonhomogeneous clutter environment. In practice, the clutter can be characterized as random variation signals, because it sometimes includes signals with very large magnitude like impulsive signal due to the system environment. The received interference signals are composed of homogeneous and nonhomogeneous data. In this situation, NHB is needed to maintain the STAP performance. The normalization using the NHD result is an effective method for removing the nonhomogeneous data. The optimum normalization can be performed by a representative value considered with a characteristic of the given data, so we propose the K-means clustering algorithm. The characteristic of random variation data due to nonhomogeneous clutters can be considered by the number of clusters, and then the representative value for selecting the homogeneous data is determined in the clustering result. In order to reflect a characteristic of the nonstationary interference data, we also investigate the algorithm for a calculation of the proper number of clusters. Through our simulations, we verified that the K-means clustering algorithm has very superior normalization and target detection performances compared with the previous introduced normalization methods.