• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.26-36
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• 2013

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charge mode, constant-current mode, and constant-voltage mode. The pre-charge mode employs the stair-case shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is specified to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 78A. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.8
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• pp.11-19
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• 1994

The matching probability P(ο/$\lambda$), of the signal sequence(ο) observed for a finite time interval with a HMM (Hidden Markov Model $\lambda$) indicates the probability that signal comes from the given model. By utilizing the fact that the probability represents matching score of the observed signal with the model we can recognize an unknown signal pattern by comparing the magnitudes of the matching probabilities with respect to the known models. Because the algorithm however uses floating point variables during the computing process hardware implementation of the algorithm requires floating point units. This paper proposes an integer algorithm which uses positive integer numbers rather than float point ones to compute the matching probability so that we can economically realize the algorithm into hardware. The algorithm makes the model parameters integer numbers by multiplying positive constants and prevents from divergence of data through the normalization of variables at each step. The final equation of matching probability is composed of constant terms and a variable term which contains logarithm operations. A scheme to make the log conversion table smaller is also presented. To analyze the qualitive characteristics of the proposed algorithm we attatch simulation result performed on two groups of 10 hypothetic models respectively and inspect the statistical properties with repect to the model order the magnitude of scaling constants and the effect of the observation length.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.323-324
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• 2013

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charge mode, constant-current mode, and constant-voltage mode. The pre-charge mode employs the stair-case shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is specified to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 78A. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.70.2-70.2
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• 2013

We present collections of optical photometry for a pre-main sequence star HBC 722. It showed large amplitude optical outburst (${\Delta}V=4.7$ mag) in 2010 and classified as a FU Orionis type object. We have been observing HBC 722 from 2011 April to 2013 May, using Camera for QUasars in EArly uNiverse (CQUEAN) attached to the 2.1 m Otto Struve telescope at the McDonald Observatory. Time-series monitoring data (minute-scale interval) were obtained in SDSS r, i and z bands to see short-scale behaviors as well as trace the long-term brightness changes after the eruption in 2010. Interestingly, it started to brighten from 2011 early summer and became brighter than the first outburst peak in our 2013 May observation. We expect that the recovering phase would result from re-increase of disk accretion rate, might attribute to distinctive short-scale color features. In this presentation, we report long- and short-timescale optical behaviors of HBC 722 in the post-outburst phase.

• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.45-45
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• 2003

To evaluate remodeling of infarcted myocardium with contrast-enhanced MRI (co-MRI) at true end-diastole (ED) MRI was performed with a Gyroscan Intera (1.5 Tesla, Philips, Netherlands) in 13 patients with acute subendocardial myocardial infarction. The First exam was done 0-15 days (mean 5.2days) after symptom onset and the second exam 28-88days (mean 49 days) after the first exam. Ce-MRI encompassing the entire left ventricle was performed with a multi-shot, turbo-field-echo, breath-hold sequence and a non-selective, inversion prepulse 10 minutes after the intravenous injection of Gd-DTPA at a dose of 0.2 mmol/kg body weight. To allow the long TD, ECG synchronization should use two RR-intervals for one acquisition of a segment of k-space by setting the heart rate to half that of the true heart rate. Trigger delay time (TD) was adjusted to the RR-interval for true end-diastolic imaging. The other typical parameters were TR=5.4ms, TE=1.6ms, voxel size=1.37${\times}$1.37${\times}$10mm, k-space data segmented into 8 segments with 32 lines of segment per two cycles over 16 cardiac circles. The thickness of hyperenhanced myocardium and epicardially nonenhanced myocardium were followed.

• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.92-92
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• 2003

To evaluate remodeling of infarcted myocardium with contrast-enhanced MRI (co-MRI) at true end-diastole (ED) MRI was performed with a Gyroscan Intera (1.5 Tesla, Philips, Netherlands) in 13 patients with acute subendocardial myocardial infarction. The First exam was done 0-15 days (mean 5.2days) after symptom onset and the second exam 28-88days (mean 49 days) after the first exam. Ce-MRI encompassing the entire left ventricle was peformed with a multi-shot, turbo-field-echo, breath-hold sequence and a non-selective, inversion prepulse 10 minutes after the intravenous injection of Gd-DTPA at a dose of 0.2 mmol/kg body weight. To allow the long TD, ECG synchronization should use two RR-intervals for one acquisition of a segment of k-space by setting the heart rate to half that of the true heart rate. Trigger delay time (TD) was adjusted to the RR-interval for true end-diastolic imaging. The other typical parameters were TR=5.4ms, TE=1.6ms, voxel size=1.37$\times$1.37$\times$10mm, k-space data segmented into 8 segments with 32 lines of segment per two cycles over 16 cardiac cycles. The thickness of hyperenhanced myocardium and epicardially nonenhanced myocardium were followed.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.67-72
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• 2020

The fifth generation (5G) mobile communication has an impact on the human life over the whole world, nowadays, through the artificial intelligence (AI) and the internet of things (IoT). The low latency of the 5G new radio (NR) access is implemented by the state-of-the art technologies, such as non-orthogonal multiple access (NOMA). This paper investigates a practical issue that in NOMA, for the practical channel models, such as fading channel environments, the successive interference cancellation (SIC) should be performed on the stronger channel users with low power allocation. Only if the SIC is performed on the user with the stronger channel gain, NOMA performs better than orthogonal multiple access (OMA). Otherwise, NOMA performs worse than OMA. Such the superiority requirement can be easily implemented for the channel being static or slow varying, compared to the block interval time. However, most mobile channels experience fading. And symbol by symbol channel estimations and in turn each symbol time, selections of the SIC-performing user look infeasible in the practical environments. Then practically the block of symbols uses the single channel estimation, which is obtained by the training sequence at the head of the block. In this case, not all the symbol times the SIC is performed on the stronger channel user. Sometimes, we do perform the SIC on the weaker channel user; such cases, NOMA performs worse than OMA. Thus, we can say that by what percent NOMA is better than OMA. This paper calculates analytically the percentage by which NOMA performs better than OMA in the practical mobile communication systems. We show analytically that the percentage for NOMA being better than OMA is only the function of the ratio of the stronger channel gain variance to weaker. In result, not always, but almost time, NOMA could perform better than OMA.

• The KIPS Transactions:PartD
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• v.18D no.4
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• pp.215-224
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• 2011

U-Health collects patient information with various kinds of sensor. Stream data can be summarized as an interval event which has aninterval between start-time-point and end-time-point. Most of temporal mining techniques consider only the event occurrence-time-point and ignore stream data change of state. In this paper, we propose the temporal mining technique considering the event change of state in U-Health. Our method overcomes the restrictions of the environment by sending a significant event in U-Health from sensors to a server. We define four event states of stream data and perform the temporal data mining considered the event change of state. Finally, we can remove an ambiguity of discovered rules by describing cause-and-effect relations among events in temporal relation sequences.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.5162-5168
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• 2013

Hopping sequences of Time Hopped Ultra Wideband Impulse Radio (TH-UWB-IR) system are to mitigate multipath fading and to provide the multiple access chances for multi users. For the reliable communications, the same pulses are repeatedly transmitted for a bit duration based on hopping sequences. The proposed decoding scheme utilizes the intervals of inter-codes in a frame where the short interval between two pulses leads to the large interference by the multipath fading. For a single user case, the proposed method obtains 0.5dB gain over the conventional method at BER=$10^{-3}$. Decoding performance of repeated pulses can be increased using the property of the hopping sequences of multi users.

• KIEAE Journal
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• v.15 no.2
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• pp.19-26
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• 2015

Purpose: Maximizing human comfort in design of medical environments depends immensely on specialized architects particularly critical care design; the study proposes Evidence-Based Design as an apparent analog to Evidence-Based Medicine. Healthcare facility designs are substantially based on the findings of study in an effort to design environments that augment care by improving patient safety and being therapeutic. On SPSS (Statistical Package for Social Science) t-test is applied to simulate two independent variables of PDR (Pre Design-Research) and POE (Post- Occupancy Evaluation). PDR is conducted on relatively new hospital Hallym University Dongtan Sacred Heart Hospital to analyse visibility from researchers' point of view, here the ICU is arranged in I-Shape. POE is applied on Dongguk University Ilsan Hospital to simulate walking on LogWare where two NS are designed based on L- Shape and Seoul St. Mary's Hospital, The Catholic University of Korea where five NS are functional for ICU Intensive Care Unit, Surgical Intensive Care Unit (SICU), Medical Intensive Care Unit (MICU), Critical Care Unit (CCU), Korean Oriental Medical Care Unit which are mostly arranged in U-Shape, and walking pattern is recognized to be in a zigzag path. Method: T-Test is applied on two dependent communication variables: walkability and visibility, with confidence interval of 95%. This study systematically analyses the Nurse Station (NS) typo-morphology, and simulates nurse horizontal circulation, by computing round route visits to patient's bed, then estimating minimum round route on LogWare stop sequence software. The visual connectivity is measured on depth map graphs. Hence the aim is to reduce staff stress and fatigue for better patients care by minimizing staff horizontal travel time and to facilitate nurse walk path and support space distribution by increasing effectiveness in delivering care. Result: Applying visibility graph and isovist field on space syntax on I- Shape, L- Shape and U- Shape ICU (SICU, MICU and CCU) configuration, I-shape facilitated 20% more patients in linear view as they stir to rise from their beds from nurse station compared to U-shape. In conclusion, it was proved that U-Shape supply minimum walking and maximum visibility; and L shape provides just visibility as the nurse is at pivot. I shape provides panoramic view from the Nurse Station but very rigorous walking.