• International Journal of Computer Science & Network Security
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• 제23권9호
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• pp.8-16
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• 2023

In Japan, high-speed ground transportation service using linear motors at speeds of 500 km/h is scheduled to begin in 2027. To accommodate 5G services in trains, a subcarrier spacing frequency of 30 kHz will be used instead of the typical 15 kHz subcarrier spacing to mitigate Doppler effects in such high-speed transport. Furthermore, to increase the cell size of the 5G mobile system, multiple base station antennas will transmit identical downlink (DL) signals to form an expanded cell size along the train rails. In this situation, the forward and backward antenna signals are Doppler-shifted in opposite directions, respectively, so the receiver in the train may suffer from estimating the exact Channel Transfer Function (CTF) for demodulation. In a previously published paper, we proposed a channel estimator based on Delay and Doppler Profiler (DDP) in a 5G SISO (Single Input Single Output) environment and successfully implemented it in a signal processing simulation system. In this paper, we extend it to 2×2 MIMO (Multiple Input Multiple Output) with spatial multiplexing environment and confirm that the delay and DDP based channel estimator is also effective in 2×2 MIMO environment. Its simulation performance is compared with that of a conventional time-domain linear interpolation estimator. The simulation results show that in a 2×2 MIMO environment, the conventional channel estimator can barely achieve QPSK modulation at speeds below 100 km/h and has poor CNR performance versus SISO. The performance degradation of CNR against DDP SISO is only 6dB to 7dB. And even under severe channel conditions such as 500km/h and 8-path inverse Doppler shift environment, the error rate can be reduced by combining the error with LDPC to reduce the error rate and improve the performance in 2×2 MIMO. QPSK modulation scheme in 2×2 MIMO can be used under severe channel conditions such as 500 km/h and 8-path inverse Doppler shift environment.

• The Journal of Korean Physical Therapy
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• 제35권4호
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• pp.105-110
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• 2023

Purpose: The purpose of this study was to determine whether the degree of dizziness affects static balance due to the disruption or absence of the senses involved in balance. To this end, the correlation between the Dizziness Handicap Inventory (DHI), which objectively evaluates dizziness, the Fourier Index (FI; Frequency bands of postural oscillation, F1, F2-4, F5-6, F7-8) and the Stability Index (ST), which evaluates static balance ability, were examined. Methods: This study investigated balance and dizziness issues in 30 healthy young adults. Participants underwent multiple tests like the DHI and tetra-ataxiometric posturography (Tetrax) under different conditions (eyes open/closed, standing on a foam-rubber pillow, and with the head in various orientations). Results: We found that F1 exhibited a weak positive correlation with dizziness under normal conditions, as well as when the eyes were closed (r=0.396, p<0.05) and the head was tilted back (r=0.375, p<0.05). Meanwhile, F5-6 showed a moderate positive correlation with dizziness in both head-back (HB: r=0.471, p<0.05) and head-forward postures (r=0.404, p<0.05). Lastly, both F7-8 and ST demonstrated a moderate positive correlation with dizziness when the head was in a forward posture (F7-8: r=0.483; ST: r=0.403, p<0.05). Conclusion: The study results indicate that the severity of dizziness affects sensory systems and balance. It also suggests that head movements, especially forward and backward, further stimulate the vestibular system, intensifying dizziness, and balance problems in affected individuals.

• Journal of Audiology & Otology
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• 제23권3호
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• pp.129-134
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• 2019

Background and Objectives: Sine a self-reported questionnaire for hearing-impaired listeners is not available by Malay language yet, it is important to develop or translate any available existing questionnaires. The aim of this study was to translate, adapt and validate the Hearing Handicap Inventory for Adult (HHIA) to be used by the audiologist among the hearing-impaired population in Malaysia. Subjects and Methods: The HHIAs was translated to Malay language using forward-backward translation techniques by four-panellists (two for each level). The translated HHIA was then reconciled and harmonized for cultural aspects and content of the questionnaire by the researchers and two expert panels before being pilot-tested among 10 hearing-impaired patients. Questionnaire validation was conducted among 80 adults with a hearing loss to calculate for Cronbach's α (internal reliability), Spearman's correlation (inter-item correlation) and factor analysis. Results: None of the translated items were removed from the scale. The overall Cronbach's α was 0.964; 0.927 and 0.934 for both social and emotional subscales, respectively. The factor analysis (force-concept inventory) demonstrated a two-structure with a strong correlation between all items in either component 1 or 2, that resembled the original scale. The Mann-Whitney test revealed significantly higher scores for those adults with a hearing loss than those adults with normal hearing. Conclusions: The Malay HHIA has been successfully translated and validated for the purpose of determining the psychosocial aspects of adults with hearing loss in the local population.

• 한국환경과학회지
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• 제31권12호
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• pp.1069-1078
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• 2022

This study investigated the weather conditions, fine particle concentration, and ion components in PM_2.5 when two cold fronts passed through Busan in succession on February 1 and 2, 2021. A analysis of the surface weather chart, AWS, and backward trajectory revealed that the first cold front passed through the Busan at 0900 LST on February 1, 2021, with the second cold front arriving at 0100 LST on February 2, 2021. According to the PM₁₀ concentration of the KMA, the timing of the cold front passage had a close relationship with the occurrence of the highest concentration of fine particles. The transport time of the cold front from Baengnyeongdo to Mt. Gudeok was approximately 11 hours . The PM₁₀ and PM_2.5 concentrations in Busan started to increase after the first cold front had passed, and the maximum concentration occurred two hours after the second cold front passed. The SO₄^2-, NO₃^-, and NH₄⁺ concentration in PM_2.5 started to increase from 1100 to 1200 LST on February 1, after the first cold front passed, and peaked at 0100 LST to 0300 LST on February 2. However, the highest Ca²⁺ concentration was recorded 2-3 hours after the second cold front had passed.

• 한국환경과학회지
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• 제31권12호
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• pp.1079-1087
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• 2022

This study investigated the effect of volcanic materials that erupted from the Nishinoshima volcano, Japan, 1,300 km southeast of the Busan area at the end of July 2020, on the fine particle concentration in the Busan area. Backward trajectory analysis from the HYSPLIT model showed that the air parcel from the Nishinoshima volcano turned clockwise along the edge of the North Pacific high pressure and reached the Busan area. From August 4 to August 5, 2020, the concentration of PM₁₀ and PM_2.5 in Busan started to increase rapidly from 1000 LST on August 4, and showed a high concentration for approximately 13 hours until 2400 LST. The PM_2.5/PM₁₀ ratio showed a relatively high value of 0.7 or more, and the SO₂ concentration also showed a high value at the time when the PM₁₀ and PM_2.5 concentrations were relatively high. The SO₄^2- concentration in PM_2.5 in Busan showed a similar trend to the change in PM₁₀ and PM_2.5 concentrations. It rose sharply from 1300 LST on August 4, at the time where it was expected to have been affected by the Nishinoshima Volcano. This study has shown that the occurrence of high concentration fine particle in Busan in summer has the potential to affect Korea not only due to anthropogenic factors but also from natural causes such as volcanic eruptions in Japan.

• PNF and Movement
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• 제21권1호
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• pp.107-117
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• 2023

Purpose: The aim of this study is to compare the immediate effects of weight-assisting methods on vastus medialis oblique (VMO) and vastus lateralis (VL) muscle activation, on the VMO/VL muscle activation ratio, and on muscle onset time in healthy subjects when ascending stairs. Methods: Healthy participants were randomly assigned to the belt group (n = 11), hand group (n = 11), and control group (n = 11). In the belt group, a belt was wrapped around the sacrum and pulled forward with both hands, moving the center of weight forward, while ascending stairs. The hand group grasped the hips with both hands and climbed stairs, assisting their weight from the rear and moving the center of weight backward, and the control group climbed the stairs without any intervention. Results: Muscle activation of the VMO decreased significantly after the intervention in the belt and hand groups, and activation of the VL muscle in both groups showed a greater decrease than that of the VMO muscle. Further, the VMO/VL muscle activation ratio increased significantly, with an improvement shown in the order of the belt group, hand group, and control group, while muscle onset time also improved in the order of the belt group, hand group, and control group. Conclusion: The belt group demonstrated the greatest effect across all dependent variables, confirming that in clinical practice, these two weight-assisting methods are more effective interventions during stair ascent for patients with knee joint instability, pain, and imbalance than no assistance.

• 대한통합의학회지
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• 제11권2호
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• pp.207-219
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• 2023

Purpose : This study was conducted to investigate the changes in trunk movement and ground reaction during sit to stand motion using visual feedback. Methods : Fifteen adults (average age: 23.53±1.77 years) participated in this study. An infrared reflective marker was attached to the body each participant for motion analysis, and the participants performed sit to stand motion while wearing a hat attached with a laser pointer, which provided visual feedback. First, the sit to stand action was repeated thrice without obtaining any visual feedback, followed by a three minute break. Next, the laser pointers attached to hats were irradiated on a whiteboard, located at a distance of 5 m in front of the chairs, on which the participants sat; a baseline was set, and the participants performed stand up movements three times under this condition. A visual feedback was provided to the participants to prevent the laser pointers from crossing the set baseline. During each stand-up movement, the position of the reflective marker attached to the subject's body was recorded in real time using an infrared camera for motion analysis. The trunk movement and ground reaction force were extracted through recorded data and analyzed according to the presence or absence of visual feedback. Results : The results indicated that in the presence of a visual feedback during the sit-to-stand movements, the range of motion of the trunk and hip joints decreased, whereas that of the knee and ankle joints increased in the sagittal plane. The rotation angle of the trunk in the horizontal plane decreased. The left and right movement speed of the center of pressure increased, the pressing force decreased, and the forward and backward movement speed of the trunk decreased. Conclusion : The results suggest that the efficiency and stability of the stand up movement of a body increase when a visual feedback is provided.

• 한국의류산업학회지
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• 제25권1호
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• pp.92-103
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• 2023

As the body shape change which occurs after middle age is the main factor affecting the fit of ready-to-wear clothes, this study was designed to classify and analyze the torso shapes of middle-aged men. This study sorted 3D body scans of 200 men aged 40-64 from the 8th Size Korea (2021) database and extracted their 47 measurement values using the Grasshopper algorithm for automatic extraction landmarks and measurements, developed by the previous research (Ryu & Song, 2022). Eight principal components (torso length, shoulder size, overall body size, abdomen prominence, back protrusion, neck inclination, upper body slope, and hip prominence) were identified and four torso shapes were classified. Shape 1 (28.5%) exhibited the shortest torso length, the narrowest shoulders, and the most protruding back. Shape 2 (21.0%) exhibited the skinniest body and the largest backward inclination of the upper body. Hence, the back appeared to be protruding, and the abdomen looked prominent. Shape 3 (25.5%) had the largest overall body size. Thus, the abdomen looked the least protruding, and it exhibited the flattest back. Shape 4 (25.0%) had the longest torso, widest shoulders, straightest neck, and the least protruding hips. This study suggested these three discriminant functions to identify a new person's torso type.

• 융합정보논문지
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• 제12권2호
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• pp.23-29
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• 2022

최근 사물인터넷(Internet of Things, IoT) 기기 사용 증가로 인해 클라우드 컴퓨팅 서버로 전송해 처리하는 데이터양이 급증하고, 그 결과 네트워크 관련 문제점(지연, 서버의 과부하 및 보안 위협)들이 크게 대두되고 있다. 특히, 연산 능력이 클라우드 컴퓨팅보다 낮은 에지 컴퓨팅은 수많은 IoT 기기들을 손쉽게 인증할 수 있는 경량화된 인증 알고리즘이 필요하다. 본 논문에서는 IoT와 에지 장치 간 익명성과 순방향·역방향의 비밀성을 보장하고 중간자 공격과 재전송 공격에 안정적이며, 에지 장치와 IoT 기기 특성에 적합한 경량화 알고리즘의 키 동의 프로토콜을 제안하였고, 제안한 키 동의 프로토콜을 기존 연구와 비교·분석한 결과 IoT 기기와 에지 장치에서 효율적으로 사용 가능한 경량화 프로토콜임을 보였다.

• Journal of Information Science Theory and Practice
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• 제10권spc호
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• pp.66-75
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• 2022

The manufacturing industry is the foundation that drives economic growth, and manufacturing innovation is essential for sustainable growth advantage and the transition into a digital economy. Therefore, major countries actively support the field of simulations, which incorporate information and communication technologies into manufacturing, and announce various policies at the national level along with increasing investment. Simulation technology virtualizes product development processes to replace physical production and experimentation of products, dramatically reducing time and costs. In South Korea, the Korea Institute of Science and Technology Information (KISTI) has supported manufacturing companies for about 14 years by providing relevant technologies. This study uses the input-output table for the Bank of Korea to analyze the economic ripple effect. First, we identified the domestic industrial sector dealing with the supercomputing-based simulation industry. Then we analyzed its ripple effects by dividing them into the production inducement effect, value-added inducement effect, employment inducement effect, and forward/backward linkage effect. Consequently, when the supercomputing simulation budget of KISTI (28.3 billion won, 2007-2020) was set as an input coefficient, the analysis showed 45.1 billion won as the production inducement effect, 24.7 billion won as the value-added inducement effect, and 282 individuals per 1 billion won as the employment inducement effect. This study is significant in that it derived the effects of the inputs by analyzing the economic ripple effects of the projects of KISTI, which have been supporting South Korean manufacturing companies for the past 14 years with supercomputing-based simulations.