• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.1009-1011
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• 2013

최근 U-헬스케어 서비스가 증가함에 따라 예방과 건강증진 등에 관심과 연구가 활발히 이루어지고 있다. 이러한 U-헬스케어에 사용되는 ECG, EMG, PPG EEG등이 스마트폰 기반의 휴대용 장비와 연동된 센서들의 연구 역시 활발히 진행 중이다. 일반적으로 PPG신호는 적외선센서를 이용하여 모세혈관의 혈중 헤모글로빈 농도 변화에 의한 맥파를 측정한다. PPG신호의 잡음을 제거하기 위해 필터를 사용하였다. 필터된 정보를 ADC하여 스마트폰으로 BlueTooth통신을 이용하여 전송한다. 최종적으로 스마트 디바이스에 PPG신호를 그린다. 제작결과 PPG아날로그 신호를 보는 것과 동일하게 스마트 디바이스에 그릴 수 있음을 보였다. 이후 PPG신호를 이용하여 혈관건강도 및 건강예방의 측정의 연구를 계속해서 한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.295-298
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• 2004

본 논문에서는 휴대용 영상장비인 비디오 레코더에 사용되는 직렬구조 리튬이온 배터리의 보호회로를 제안하였다. 제안된 보호회의에서는 정적 전류소모가 큰 전지 상태 검출기를 공유하였고 배터리의 상태에 따른 저 전력모드 변환을 가능하게 하여 보호회로의 효율성을 극대화하였다. 제안된 회의는 0.35um 표준 CMOS 공정을 사용하여 검증하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.768-769
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• 2015

센서를 이용한 산업은 다양하게 존재하며 그 범위는 점점 넓어지고 있다. 각종 생산 장비에서부터 각종 소비 장치까지 다양한 환경에 여러 종류의 센서들이 활용되고 있다. 그중 헬스 케어 분야는 응용분야가 다양하게 발전하고 있다. 헬스케어의 목적은 이용자가 가질 수 있는 위험 요소를 미리 측정 제거하여 건강한 삶을 살도록 하는 것이다. 이에따라 다양한 방면에서 활용되고 있으며, 연구되고 있다. 본 논문에서는 헬스케어의 여러 분야 중 사용자 관리 측면에서 센서를 이용한 주거 환경 개선 프로그램의 일환으로 사용자가 소지할 수 있는 휴대용 물품을 통하여 사용자의 신체 정보를 입수한다. 또한 사용자가 위치한 공간의 환경정보를 센서를 이용하여 측정하고, 이후 센서가 감지하는 사용자의 데이터를 근거로 미리 설정한 환경에 맞게 주변 환경을 제어하는 시스템을 구성하고 연구한다.

• The Journal of the Acoustical Society of Korea
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• v.39 no.5
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• pp.435-440
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• 2020

Single-beam acoustic tweezers that are capable of manipulating micron-size particles in a non-contact manner have been used in many biological and biomedical applications. Current single-beam acoustic tweezer systems developed for in vitro experiments consist of a function generator and a power amplifier, thus the system is bulky and expensive. This configuration would not be suitable for in vivo and clinical applications. Thus, in this paper, we present a portable single-beam acoustic tweezer system and its performances of trapping and manipulating micron-size objects. The developed system consists of an Field Programmable Gate Array (FPGA) chip and two pulsers, and parameters such as center frequency and pulse duration were controlled by a Personal Computer (PC) via a USB (Universal Serial Bus) interface in real-time. It was shown that the system was capable of generating the transmitting pulse up to 20 MHz, and producing sufficient intensity to trap microparticles and cells. The performance of the system was evaluated by trapping and manipulating 40 ㎛ and 90 ㎛ in diameter polystyrene particles.

• Journal of Advanced Navigation Technology
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• v.22 no.4
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• pp.288-294
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• 2018

The entertainment system of the aircraft has changed its paradigm in the form of using passenger electronic devices instead of using a fixed monitor. This has simplified the on-board equipment while the risk of safety has increased with the electric charging of portable electronic devices. Unlike personal portable electronic devices that do not have a transmission function, the use of Wi-Fi enabled electronic devices(T-PED) is allowed and the battery is required to be charged in the cabin. In this study, we used the NASA Aviation Safety Reporting System to investigate the effects of changes in wireless environment and entertainment service. Based on this, we analyzed the risks of personal electronic devices by sharing event occurrence cases caused by in-flight electronic equipment or passenger portable electronic devices(especially smart phones) from the viewpoint of aircraft safety management. This analysis includes identification of potential hazards and risk assessment, and finally the strategies for risk mitigation for safe use of portable electronic devices are suggested.

• Tunnel and Underground Space
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• v.15 no.1 s.54
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• pp.28-38
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• 2005

According to the recent development of measurement system utilizing one or a set of boreholes, visualization of the explored underground became to be a major issue. It induced even the introduction of monitoring apparatuses on the borehole wall with multi-function tool, but the usage of these was often limited by where is unfavorable rock condition and a few of engineers can approach. And so, a portable type of borehole camera with only the essential function has been investigated and a few of commercial models about this is recently being applied into the field condition. This paper was based on the monitoring results obtained using a commercial model by Dr. Nakagawa. Discontinuities in rock mass were the topic for the visualization, and it was studied how can visualize their three dimensional distribution and what a numerical formulation is needed and how to understand the visualization result. The numerical formulation was based on the geometric correlation between the dip direction / dip of discontinuous plane and the trend / plunge of borehole, a set of the equation of a plane was induced. As field application of this into two places, it is found that the above visualization methodology will be especially an useful geotechlical tool for analyzing the local distribution of discontinuities.

• Journal of the Korea Society for Simulation
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• v.28 no.2
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• pp.139-147
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• 2019

A MANPADS(Man Portable Air Defense System), which tracks infrared energy, is light enough for individuals to carry and can against to a variety of aircraft, making it widely deployed around the world, posing a major threat to aircraft. A flare has been developed as an IRCM(Infrared Countermeasures) that protects the life of friendly aircraft and combatants by deceiving such guided missiles. However, DIRCM, which can overcome the problems of existing IRCM, is being developed mainly in some developed countries, and the need for it has been increasing gradually. This paper modeled first generation IR seeker of AM modulation method, the second generation IR seeker of FM modulation method, and the third generation IR seeker of pulse modulation method among various MANPADS, and modeled the scattering light phenomenon in the seeker when laser beams are investigated in DIRCM. Using this, jamming simulations were performed in various engagement environments of the MANPADS and aircraft equipped with DIRCM, and the miss distance of the guided missiles and aircraft were analyzed. Simulation results show that DIRCM, which irradiates a modulated laser beam with one jamming code, deceives both first, second and third generation MANPADS at 1km and 2km of engagement distance. In particular, the survival rate of aircraft equipped with DIRCM increased when the distance of engagement increased from 1km to 2km, and the survival rate was at least 99% at 2km of engagement distance.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.263-265
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• 2000

휴대용 무선 장비의 보급으로 많은 사용자들이 좀 더 많은 컨텐츠를 요구를 하게 될 것이다. 서비스 공급업체는 좀 더 많은 무선 컨텐츠를 개발해야 할 것이다. 서비스 업체는 기존의 인터넷 컨텐츠의 근간을 이루는 언어인 HTML을 무시하고 무선 인터넷 언어인 WML로 컨텐츠를 새롭게 개발할 경우, 엄청나게 많은 시간과 비용을 소비해야 할 것이다. 이에 본 논문은 기존의 HTML 컨텐츠를 무선 인터넷 언어인 WML로 실시간 변환하는 컨텐츠 변환기를 설계하고 구현하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.550-552
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• 2004

최근 휴대폰, PDA, 노트북 등의 모바일 제품의 인기에 따라 모바일에 대한 소비자의 관심이 증대되고 있으며, 대형 네트워크 장비보다 소형의 개인 휴대용의 모바일 제품의 성장세가 두드러지고 있다. 이러한 추세에 따라 무선랜에 대한 관심도 증대되고 있다. 본 논문에서는 기존의 ARM 프로세서를 기반으로 802..11 무선랜 환경에 맞는 네트워크 프로세서 구조에 대한 연구를 수행하였다. 그 결과 전송과 수신이 빈번하게 동시에 일어나는 무선랜 환경에서는 multi-threading을 처리할 수 있는 프로세서가 구조(SMT)가 Superscalar 구조에 비해 높은 성능 향상 폭을 보여주었다

• Journal of Environmental Impact Assessment
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• v.27 no.4
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• pp.378-393
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• 2018

As atmospheric fine dust problems in Korea become more serious, there are growing needs to find the concentration of fine particles in indoor and outdoor areas and there are increasing demands for sensor-based portable monitoring devices capable of measuring fine dust concentrations instantly. The low-cost portable monitoring devices have been widely manufactured and used without the prescribed certification standards which would cause unnecessary confusion to the concerned public. To evaluate the reliability those devices and to improve their usability, following studies were conducted in this work; 1) The comparisons between sensor-based devices and comparison with more accurate devices were performed. 2) Several experiments were conducted to understand usefulness of the portable monitoring devices. As results, the absolute concentration levels need to be adjusted due to insensitivity of the tiny light scattering sensors in the portable devices, but their linearity and reproducibility seem to be acceptable. By using those monitoring devices, users are expected to have benefits of recognizing the changes of concentration more quickly and could help preventing themselves from the adverse health impacts.