• Journal of the Korea Society of Computer and Information
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• v.18 no.11
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• pp.1-12
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• 2013

In multi-core processors, Last Level Cache(LLC) can reduce the speed gap between the memory and the core. For this reason, LLC has big impact on the performance of processors. LLC is composed of shared cache and private cache. In computer architecture community, most researchers have mainly focused on the management techniques for shared cache, while management techniques for private cache have not been widely researched. In conventional private LLC, memory is statically assigned to each core, resulting in serious performance degradation when the workloads are not fairly distributed. To overcome this problem, this paper proposes the replacement policy for managing private cache of LLC efficiently. As proposed core-aware cache replacement policy can reconfigure LLC dynamically, hit rate of LLC is increases drastically. Moreover, proposed policy uses 2-bit saturating counters to improve the performance. According to our simulation results, the proposed method can improve hit rates by 9.23% and reduce the access time by 12.85% compared to the conventional method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.3
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• pp.229-235
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• 2019

The implementation of an in-band full-duplex wireless communication system is demonstrated in this study. In the analog/RF domain, the self-interference(SI) signal is reduced using a separate antenna for the transmitter and receiver paths, and most of the SI signal is canceled in the digital domain. A software defined radio(SDR) is used to implement the in-band full-duplex wireless communication system. The USRP X310 device uses transmitting and receiving antennas. By adjusting the gain of the transmitting and receiving ends of the SDR device, the magnitude of the SI signal entering the receiving antenna, and the size of the received signal from the outside, are both set to -64 dB. To verify the in-band full-duplex wireless communication performance, the source data is image and orthogonal frequency-division multiplexing is used for modulation. A WiFi standard frame with a carrier frequency of 2.67 GHz and bandwidth of 20 MHz is used. In the received signal, the SI signal is canceled by digital signal processing and the SI signal is attenuated by up to 34 dB. OFDM demodulation was impossible when the SI signal was not removed. However, the bit error rate is reduced to $2.63{\times}10^{-5}$ when the SI signal is attenuated by 34 dB, and no error is detected in the 100 Mbit data output as a result of passing through the Viterbi decoder.

• Journal of Korean Dental Hygiene Science
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• v.4 no.1
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• pp.29-37
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• 2021

Background: The selection of an occupation is typically based on individuals' personalities and the characteristics of occupations, which significantly affect occupational consciousness. The present study aimed to enhance the occupational achievement level of and provide fundamental data for student counseling in order to develop competitive professional workers by understanding the occupational consciousness of freshmen and motivating them as dental hygienists with career development plans, as freshmen majoring in dental hygiene eventually play a significant role in the field of dentistry as dental hygienists. Methods: The surveys were distributed to 160 freshmen in the dental hygiene department and were subsequently collected. The data from 142 surveys were used for analysis, as 18 surveys were excluded due to insincere responses. The survey contents included questions related to major selection and satisfaction, including motives for selecting a dental hygiene major, prior knowledge on a dental hygiene major and a career as a dental hygienist, satisfaction level of the major, and reasons for dissatisfaction in cases if applicable, as well as questions related to occupational consciousness, including career prospects for dental hygienists, opinions on the occupation, and conditions of job selection. Results: High employment rate with good salary level ranked highest (43.7%) among motives to apply the dental hygiene major, followed by the desire to be a professional worker (21.1%) and recommendation by acquaintances. Of those who responded, 50.7% indicated a normal level of satisfaction with the major, and 69.9% responded that they had prior knowledge regarding the dental hygiene major and/or field of dental hygiene. These results may be due to youth unemployment and the occurrence of job preparation immediately after students enter university, which is a result of the difficulty in job seeking. In terms of career prospects, 48.6% of students responded with "growing a little bit," followed by "growing a lot" (28.9%), "no difference from now" (21.1%), and "other" (1.4%). Regarding opinions on the occupation, 65.5% responded that occupation was an tool with which to make and income or a living, 23.2% responded that occupation was for dreams and self-realization, and 11.3% responded that occupation was for success in life and maintaining social status. Regarding the conditions of job selection, the responses included that the workplace had good working conditions (39.4%), good interpersonal relationships (21.8%), and a higher salary (18.3%). This may reflect the change in work ethics among university students, according to the trend of the times. Conclusion: Based on the results of the present study, we found that educational guidance to enhance the level of satisfaction with the major, and career guidance to understand and apply the clear vision and long-term job security are necessary.

• Phonetics and Speech Sciences
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• v.12 no.4
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• pp.81-90
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• 2020

This paper describes a method of building Korean conversational speech data in the emergency medical domain and proposes an annotation method for the collected data in order to improve speech recognition performance. To suggest future research directions, baseline speech recognition experiments were conducted by using partial data that were collected and annotated. All voices were recorded at 16-bit resolution at 16 kHz sampling rate. A total of 166 conversations were collected, amounting to 8 hours and 35 minutes. Various information was manually transcribed such as orthography, pronunciation, dialect, noise, and medical information using Praat. Baseline speech recognition experiments were used to depict problems related to speech recognition in the emergency medical domain. The Korean conversational speech data presented in this paper are first-stage data in the emergency medical domain and are expected to be used as training data for developing conversational systems for emergency medical applications.

• Journal of Broadcast Engineering
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• v.27 no.2
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• pp.244-247
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• 2022

In this paper, the performance of the decoding schemes using linear MMSE filters in the frequency and time domains and the reinforcement Gauss-Seidel algorithm for the orthogonal time frequency space (OTFS) system that can improve robustness under high-speed mobile environments are compared. The reinforcement Gauss-Seidel algorithm can improve the bit error rate performance by suppressing the noise enhancement. The simulation results show that the performance of the decoding scheme using the linear MMSE filter in the frequency domain is severely degraded due to the effect of Doppler shift as the mobile speed increases. In addition, the decoding scheme using the reinforcement Gauss-Seidel algorithm under the channel environment with 120 km/h and 500 km/h speeds outperforms the decoding schemes using linear MMSE filters in the frequency and time domains.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.151-158
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• 2022

In this paper, parameter characteristics such as pH effect, isotherm, kinetic and thermodynamic parameters and competitive adsorption of dyes including malachite green (MG), direct red 81 (DR 81) and thioflavin S (TS), which have different functional groups, being adsorbed onto activated carbon were investigated. Langmuir, Freundlich and Temkin isotherm models were employed to find the adsorption mechanism. Effectiveness of adsorption treatment of three dyes by activated carbon were confirmed by the Langmuir dimensionless separation factor. The mechanism was found to be a physical adsorption which can be verified through the adsorption heat calculated by Temkin equation. The adsorption kinetics followed the pseudo second order and the rate limiting step was intra-particle diffusion. The positive enthalpy and entropy changes showed an endothermic reaction and increased disorder via adsorption at the S-L interface, respectively. For each dye molecule, negative Gibbs free energy increased with the temperature, which means that the process is spontaneous. In the binary component system, it was found that the same functional groups of the dye could interfere with the mutual adsorption, and different functional groups did not significantly affect the adsorption. In the ternary component system, the adsorption for MG lowered a bit, likely to be disturbed by the other dyes meanwhile DR 81 and TS were to be positively affected by the presence of MG, thus resulting in much higher adsorption.

• Journal of Broadcast Engineering
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• v.27 no.6
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• pp.848-859
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• 2022

This paper presents a novel 360-degree video streaming system for large-scale immersive displays and its ongoing implementation. Recent VR systems aim to provide a service for a single viewer on HMD. However, the proposed 360-degree video streaming system enables multiple viewers to explore immersive contents on a large-scale immersive display. The proposed 360-degree video streaming system is being developed in 3 research phases, with the final goal of providing 6DoF. Currently, the phase 1: implementation of the 3DoF 360-degree video streaming system prototype is finished. The implemented prototype employs subpicture-based viewport-dependent streaming technique, and it achieved bit-rate saving of about 80% and decoding speed up of 543% compared to the conventional viewport-independent streaming technique. Additionally, this paper demonstrated the implemented prototype on UCSB AlloSphere, the large-scale instrument for immersive media art exhibition.

• Journal of the Korean Geotechnical Society
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• v.26 no.2
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• pp.23-32
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• 2010

This study was especially conducted to find out the characteristics of the lightweight air-mixed soil (slurry density 10 kN/$m^3$) containing silt related to water. Compression strength, permeability, and capillary height of the lightweight air-mixed soil were studied, and also to support these studies, the structure of that soil was analyzed in detail. Air bubbles of various sizes are inside the lightweight air-mixed soil, and its distribution in a location is almost constant. A numerous tiny pores are inside the air bubbles so that the lightweight air-mixed soil can be saturated with water. Porosity is also estimated through the image analysis. Peak strength of the lightweight air-mixed soil is not dependent on water, but behavior of stress-strain is affected by the water. Permeability is about $4.857{\times}10^{-6}cm/sec$, which is a little bit higher than the clay's permeability. Capillary rise occurs rapidly at the beginning of the test until the lapse of 100 minutes and then its increase rate becomes slow. The capillary rise causes the increase of the density of the lightweight air-mixed soil, and thus it is required to pay attention to this phenomenon during structure design and maintenance of the lightweight air-mixed soil.

• Journal of Service Research and Studies
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• v.13 no.4
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• pp.70-96
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• 2023

Recently, the high turnover rate of nursing staff and the problems caused by increased job stress have been highlighted as social issues, and the problem of 'Taeoom' in nursing organizations has received increasing attention. Therefore, the purpose of this study is to propose a solution to the Taeoom problem, including bullying in the nursing work environment, as there is an urgent need to find a solution to prevent and overcome this problem. For this purpose, based on the S-O-R framework and previous studies, job stress and turnover intention were derived as outcome variables of Taeoom and communication competence as an antecedent factor, and a research model was constructed with the expectation that mindfulness and social support would serve as moderating variables to help overcome this problem. Data were collected through a survey of 300 nurses who had experienced Taeoom within the past year, and the hypotheses were tested using a structural equation model. The results revealed that the higher the communication competence of nurses, the less they perceived the damage of Taeoom, and that the damage caused by Taeoom leads to turnover intention through high job stress. In addition, mindfulness and social support significantly attenuated the positive effects of burnout on job stress and job stress on turnover intention, respectively. The significance of this study is that it proposed an extended P-S-O-R framework by adding a prevention stage to the existing S-O-R framework, and further tested the moderating effects of mindfulness and social support variables. It is expected that the findings of this study will provide concrete guidelines to prevent and overcome the Taeoom problem that can be applied in practice.

• International Journal of Computer Science & Network Security
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• v.23 no.10
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• pp.1-10
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• 2023

This paper proposes a method to extend Inter-Carrier Interference (ICI) canceling Orthogonal Frequency Division Multiplexing (OFDM) receivers for 5G mobile systems to spatial multiplexing 2×2 MIMO (Multiple Input Multiple Output) systems to support high-speed ground transportation services by linear motor cars traveling at 500 km/h. In Japan, linear-motor high-speed ground transportation service is scheduled to begin in 2027. To expand the coverage area of base stations, 5G mobile systems in high-speed moving trains will have multiple base station antennas transmitting the same downlink (DL) signal, forming an expanded cell size along the train rails. 5G terminals in a fast-moving train can cause the forward and backward antenna signals to be Doppler-shifted in opposite directions, so the receiver in the train may have trouble estimating the exact channel transfer function (CTF) for demodulation. A receiver in such high-speed train sees the transmission channel which is composed of multiple Doppler-shifted propagation paths. Then, a loss of sub-carrier orthogonality due to Doppler-spread channels causes ICI. The ICI Canceller is realized by the following three steps. First, using the Demodulation Reference Symbol (DMRS) pilot signals, it analyzes three parameters such as attenuation, relative delay, and Doppler-shift of each multi-path component. Secondly, based on the sets of three parameters, Channel Transfer Function (CTF) of sender sub-carrier number n to receiver sub-carrier number l is generated. In case of n≠l, the CTF corresponds to ICI factor. Thirdly, since ICI factor is obtained, by applying ICI reverse operation by Multi-Tap Equalizer, ICI canceling can be realized. ICI canceling performance has been simulated assuming severe channel condition such as 500 km/h, 8 path reverse Doppler Shift for QPSK, 16QAM, 64QAM and 256QAM modulations. In particular, 2×2MIMO QPSK and 16QAM modulation schemes, BER (Bit Error Rate) improvement was observed when the number of taps in the multi-tap equalizer was set to 31 or more taps, at a moving speed of 500 km/h and in an 8-pass reverse doppler shift environment.