• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.469-470
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• 2023

이 논문은 이미지 처리와 머신 러닝 분야에서 중요한 주제 중 하나인 알고리즘 성능과 효율성에 대한 연구이다. 역전파 알고리즘과 상대적으로 새로운 Forward-Forward 알고리즘을 비교하고 분석해 보니 Forward-Forward 알고리즘이 역전파 알고리즘보다 비교적 높은 정확도를 확인할 수 있었다.

• The Journal of Korean Physical Therapy
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• v.30 no.4
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• pp.108-111
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• 2018

Purpose: This study examined the effects of the forward head posture and tension type headache on neck movement among office workers. Methods: The subjects were 6 male and 21 female patients composed of a forward head posture group, forward head posture group with a tension type headache and a normal group. Each group consisted of 2 males and 7 females. The cranio-vertebral angle of the head and the angle of motion of the neck were measured. SPSS 23.0 was used for data analysis and one-way ANOVA was performed for the mean comparison of the neck movements in the three groups. Results: The participants had a limitation in the movement of all necks between the forward head posture group and forward head posture with tension type headache group compared to the normal subjects. The forward head posture with tension headache group had limited neck extension and lateral bending compared to the forward head posture group. Conclusion: Office workers have limitations in the movement of the neck when they are accompanied by forward head posture and tension headache. In particular, when accompanied with a tension headache, there is a restriction on the neck extension and side bending. This study is expected to provide basic data for the relief of tension headache and the treatment of forward head posture in office workers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.361-370
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• 2008

Cooperative relaying permits one or more relay to transmit a signal from the source to the destination, thereby increasing network coverage and spectral efficiency. The performance of cooperative relaying is often measured as outage probability. However, appropriate measure for the channel quality is outage capacity. Although the outage probability for cooperative relaying protocol has been analyzed before, very little research has been addressed for the outage capacity. This paper is the first of its kind to derive a closed-form analytical solution of outage capacity using fixed decode and forward relaying and amplify and forward relaying in dissimilar Rayleigh fading channels, considering channel coefficients known to the receiver side. The analytical results show a tradeoff between the SNR and the number of relays for specific outage capacity. A comparison between decode and forward relaying and amplify and forward relaying shows that decode and forward relaying outperforms amplify and forward relaying for a large number of relays.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.6
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• pp.464-470
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• 2022

A new type of soft-switching forward converter is proposed in this study. By adding only a few components, the inductor, diode, switch, and capacitor exhibit higher efficiency than the conventional forward converter. Therefore, the switching losses of the proposed forward converter are considerably reduced compared with those of the conventional forward converter. In addition, the reset winding is not used because of the capacitor employed in the auxiliary circuit. The auxiliary capacitor is adopted for zero-current-transition operation and for dissipating magnetization energy. The performance of the proposed forward converter is validated using experimental results from a 60 W, single-output, forward converter prototype, and design guidelines are presented.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.19-25
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• 1999

To achieve high efficiency in high power and high frequency applications, reduction of switching losses and noise is very important. In this paper, an improved zero voltage switching forward dc/dc converter is proposed. The proposed converter is constructed by using energy recovery snubbers in parallel with the main switches and output diodes of the conventional forward dc/dc converter. Due to the use of the energy recovery snubbers in the primary and secondary side, the proposed converter achieves zero-voltage-switching turn-off without switching losses for switching devices and output rectification diodes. The complete operating principles and experimental results will be presented.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.6
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• pp.560-567
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• 2004

In this paper, the design and implementation of a high power(300W) forward converter using a planar transformer is presented. The overall size and volume of the converter is decreased by replacing a planar transformer in stead of using a conventional winding transformer. Due to the decreased size and volume, power density of the applied forward converter is increased. Also, in this paper, the 300W ZVS forward converter with active clamp snubber circuit is compared to the 300W hard switching forward converter planar transformer, the decreased size and volume, the 300W ZVS forward converter with active clamp snubber circuit, 30W hard switching forward converter.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2698-2700
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• 1999

The MRC minimizes a parasitic oscillation using the resonant tank circuit absorbed parasitic reactances existing in a converter circuit. So the converter is capable of operating at a high switching and also reducing the losses. But the resonant voltage stress across a resonant switch is 4-5 times a input voltage. This high voltage stress increases the conduction loss in MOSFET. In this paper, the CM forward MRC with synchronous rectifier and AT forward MRC are compared about efficiency and semiconductor stress. For analysis, we have built a 50W CM forward MRC and a 50W AT forward MRC. in which the input voltage is 48V, output voltage is 5V, each other. The measured voltage stress is about 170V of 2.9 times the input voltage in the AT Forward MRC, about 106V of 1.8 times the input voltage in CM forward MRC, and the efficiency is 81.05% in AT Forward MRC, 83.61% in CM forward MRC.

• PNF and Movement
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• v.18 no.1
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• pp.45-53
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• 2020

Purpose: This study investigated the correlation between standing balance and head-forward posture in adolescents. Methods: The participants in this study were 15 female adolescents. We took photographs of the participants' craniovertebral angle with a digital camera to determine the degree of head-forward posture. Standing balance was evaluated using the 30-second Romberg test of BT4. The measurements were taken on a stable-support surface and on an unstable-support surface using a balance pad. The data measured in this study were analyzed using SPSS version 23.0, and the statistical significance level α was established as 0.05. Pearson correlation coefficient analysis was performed to identify the correlation between the degree of head-forward position of the participants and their balance ability. Results: When we measured 30 seconds of the Romberg test, we observed that, with their eyes open, the participants' head-forward posture and balance were not correlated. However, with their eyes closed, there was a strong correlation between the forward position of the head and the balance ability, which declined as the head position increased. Conclusion: Adolescents with severe head-forward posture exhibited problems with balance in posture control with closed eyes when visual information was not available. It can be inferred that an abnormality occurs in proprioceptor sensation due to their habitual head-forward posture. Education on correct posture and preventive activities should be recommended to improve the health of such adolescents and avoid possible future problems of physical deterioration.

• The Journal of Korean Society for Radiation Therapy
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• v.15 no.1
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• pp.41-52
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• 2003

I. Purpose The dose distribution in normal tissues and target lesions is very important in the treatment planning. To make the uniform dose distribution in target lesions, many methods has been used. Especially in the head and neck, the dose inhomogeneity at the skin surface should be corrected. Conventional methods have a limitation in delivering the enough doses to the planning target volume (PTV) with minimized dose to the parotid gland and spinal cord. In this study, we investigated the feasibility and the practical QA methods of the forward IMRT. II. Material and Methods The treatment plan of the forward IMRT with the partial block technique using the dynamic multi-leaf collimator (dMLC) for the patients with the nasopharyngeal cancer was verified using the dose volume histogram (DVH). The films and pinpoint chamber were used for the accurate dose verification. III. Results As a result of verifying the DVH for the 2-D treatment plan with the forward IMRT, the dose to the both parotid gland and spinal cord were reduced. So the forward IMRT could save the normal tissues and optimize the treatment. Forward IMRT can use the 3-D treatment planning system and easily assure the quality, so it is easily accessible comparing with inverse IMRT IV. Conclusion The forward IMRT could make the uniform dose in the PTV while maintaining under the tolerance dose in the normal tissues comparing with the 2-D treatment.

• Journal of Korean Physical Therapy Science
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• v.30 no.3
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• pp.23-30
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• 2023

Background: Flexion of cervical and lumbar joints is required when viewing a smartphone screen. Thus, these joints are overused, together with the surrounding joints and muscles. Long-term use of smartphones will cause changes in cervical and lumbar posture. The effect on forward head posture will vary, depending on the angle of cervical flexion start position in relation to the smartphone. This study investigated how forward head posture changes over time when using a smartphone at 20° and 40° cervical flexion start positions. Design: Cross-sectional study. Methods: Twenty-five subjects with a forward head posture angle of 35° or less participated in the study. A Forward Head Posture app on the participants' smartphones measured forward head posture 5 and 10 minutes after watching videos on their smartphones. Cervical range of motion was used to set a smartphone watching start posture of 20° and 40° of cervical flexion. Results: There was no significant difference in forward head posture, irrespective of cervical flexion start position, but the angle of forward head posture increased more at cervical flexion of 40° than at cervical flexion of 20°. There was no significant difference in what according to smartphone video viewing times, but the angle of forward head posture increased over time. Conclusion: An increase in forward head posture over time with smartphone usage poses a potential risk of neck and shoulder pain. Therefore, smartphone users should avoid prolonged screen time.