• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.222-226
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• 2001

In this paper, 2.4GHz RF Module using Even Harmonic Mixer(EHM) was designed and fabricated for Direct conversion(DC) system. By minimizing performance degradation of DC system with DC offset and LO radiation, the capability of minimization and one chip solution in wireless system was proposed. The designed EHM using anti-parallel diode pair represented 9dB conversion loss and about -60dBm 2LO leakage radiation in RF port, and output reflection and reverse transmission characteristic of low noise amplifier was improved. So superior DC offset suppression characteristic is expected. RF Module which consists of EHM, LNA, RF amplifier, Frequency synthesizer and Duplexer was designed and fabricated.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.637-640
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• 2010

VoIP 패킷을 전송하는데 있어서 MAC Header는 패킷의 데이터 크기에 비해 많은 대역폭을 할당 받고 있기에 제한된 무선자원의 사용에 부담이 되고 있다. 이러한 문제를 해결하기 위해 패킷 압축기법이나 패킷번들링을 이용하여 부하를 줄이기 위한 연구가 진행되고 있으며, 효율적인 무선 자원 이용의 향상을 가져올 수 있다. 따라서 본 연구에서는 WiMAX 시스템에서 스케줄링 서비스에 따른 VoIP서비스에서의 성능 분석을 하였다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.2
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• pp.81-88
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• 2023

SHM (Structural Health Monitoring) technique for monitoring aircraft structural health and damage, EHM (Engine Health Monitoring) for monitoring aircraft engine performance, and APM (Application Performance Management) is used for each function. APMS (Airplane Performance Monitoring System) is a program that comprehensively applies these techniques to identify the difference between the performance manual provided by the manufacturer and the actual fuel mileage of the aircraft and reflect it in the flight plan. The main purpose of using APMS is to understand the performance of each aircraft, to plan and execute flights in an optimal way, and consequently to reduce fuel consumption. First, it is to check the fuel efficiency trend of each aircraft, check the correlation between the maintenance work performed and the fuel mileage, find the cause of the fuel mileage increase/decrease, and take appropriate measures in response. Second, it is to find the cause of fuel mileage degradation in detail by checking the trends by engine performance and fuselage drag effect. Third, the APMS is to be used in making maintenance work decisions. Through APMS, aircraft with below average fuel mileage are identified, the cause of fuel mileage degradation is identified, and appropriate corrective actions are determined. Fourth, APMS data is used to analyze the economic analysis of equipment installation investment. The cost can be easily calculated as the equipment installation cost, but the benefit is fuel efficiency improvement, and the only way to check this is the manufacturer's theory. Therefore, verifying the effect after installation and verifying the economic analysis is to secure the appropriateness of the investment. Through this, proper investment in fuel efficiency improvement equipment will be made, and fuel efficiency will be improved.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.975-978
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• 2010

그룹통신에서의 작업자 간에 긴밀한 통신을 필요로 하는 경우에 기존의 무전기나 주파수 공용통신은 음성 품질이 매우 열악하여 통신 신뢰성이 매우 낮다. 이러한 문제를 해결하기 위해 그룹통신에서 VoIP를 활용하는 것이 요구된다. VoIP를 이용할 경우 20ms정도의 짧은 주기로 인하여 패킷마다의 헤더로 인한 오버헤드가 발생하는데 이를 해결하기 위해 그룹통신에서의 패킷번들링이 요구된다. 따라서 본 연구에서는 패킷번들링을 적용한 상태에서 VoIP를 이용한 그룹통신 성능분석을 하였다.

• Asia Marketing Journal
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• v.16 no.1
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• pp.169-193
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• 2014

The earlier studies have verified that brand values have significant impact on financial values such as stock return and stock price to justify marketing costs for brand building. Except for Mizik and Jacobson (2008), however, little research has addressed what kinds of brand components composing brand values have a significant relationship with financial values. As a follow-up research of Mizik and Jacobson (2008), this research focuses on what kinds of relationships exist between the unanticipated change of each brand asset component and stock return, one of the financial values. The authors selected six brand asset components from the Korea-Brand Power Index(K-BPI) data in which 'Top of Mind,' 'Unaided Awareness,' and 'Aided Awareness' are brand awareness measures and 'Image,' 'Purchase Intention,' and 'Preference' are brand loyalty measures. Out of those six brand components, they found that unanticipated changes of 'Top of Mind,' 'Unaided Awareness,' 'Image,' and 'Preference' have significantly positive effect on unexpected stock return change. Therefore, they conclude that these four brand asset components provide incremental information in explaining unanticipated stock return.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.35 no.4
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• pp.139-162
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• 2022

Objectives : The review was conducted to validate the effectiveness of herbal medicines on acne. Methods : Randomized controlled trials(RCTs) reporting the effects of herbal medicine treatment on acne were searched through seven electronic databases from the time of application of the material to October 2021. Cochrane Collaboration's Risk of Bias was used to assess the risk of bias. Analysis was performed using Review Manager 5.4 and R 4.1.0 Meta, Metafor program. Results : 34 RCTs was selected and meta-analysis was performed with 30 studies. The inflammatory lesion count of the herbal medicine(MD=0.29, 95% CI:-0.59-0.01, p<0.01, I²=80%) and the non inflammatory lesion count of herbal medicine(MD=-0.30, 95% CI:-0.70-0.10, p<0.01, I²=78%) were seen. The score of IGA(RR=1.43, 95% CI:0.90-2.27, p<0.91, I²=0%), VISIA(MD=0.36, 95% CI:0.21-0.51, p=0.07, I²=40%), effective rate(RR=1.23, 95% CI:1.05-1.44, p<0.01, I²=98%), DLQI(MD : 0.59, 95% CI:0.14-1.04, p=0.07, I²=63%) and recurrence rate(RR=0.36, 95% CI:0.23-0.58, p=0.73, I²=0%) were seen. The effective rate of herbal medicine were statistically higher that of the control group(WM)(RR=1.19, 95% CI:1.04-1.37, p<0.01, I²=97%). As a result of dividing the treatment groups into OHM, EHM, and OEHM, the EHM group(RR=1.17, 95% CI:0.79-1.72, p<0.01, I²=99%) showed the most statistically significant effect. The overall risk of bias of the included studies was some concerns. No serious adverse effects were observed. Conclusions : This review found the effectiveness of herbal medicine for acne.