• 융합보안논문지
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• 제9권2호
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• pp.79-84
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• 2009

현재의 동영상 파일은 WMV(Window Media Video)형식과 같은 극일 포맷과 압축 기술들이다. 이 같은 파일 포맷과 압축 기술을 이용한 동영상들은 화질과 압축율에 문제점을 가지고 있다. 이에 본 논문은 Macromedia(Adobe 사가 인수함)사에서 개발한 FLV(Flash Video)와는 다른 FLY 솔루션 EZ-MOV를 설계 및 구현하였다. EZ-MOV는 다음과 같은 장점들을 가지고 있다. 첫째, FLV플레이어가 배속이 가능하며 자체 DRM이 내장 죄어 있어서 불법 녹화가 불가능하고 둘째, WMV 형식 파일을 FLV로 인코딩시에 최대한 50%까지 무손실로 압축이 가능하며 셋째, 버퍼링 없는 동영상 스트리밍이 가능하다. 넷째, 스트리밍 서버 없이도 FLV 파일을 스트리밍으로 서비스가 가능하다. 다섯째, 다운로드와 스트리밍을 병행한 동영상 서비스도 가능하다. 여섯째, 양방향으로의 서비스도 가능하다.

• 대한족부족관절학회지
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• 제14권2호
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• pp.109-114
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• 2010

Purpose: The purpose of this study was to report the surgical outcome of reconstruction of neglected chronic Achilles tendon ruptures with various methods including Achilles tendon allograft. Materials and Methods: Between October 2003 and November 2008, 8 consecutive neglected chronic Achilles tendon ruptures with the defect gap of more than 4 cm underwent surgical reconstruction including V-Y advancement, gastrocnemius fascial turn-down flap, flexor hallucis longus transfer and Achilles tendon allograft. There were 7 males and 1 female who were evaluated at more than 18 months after surgery. At the time of followup, all patients were assessed with regard to postoperative complications, their self-reported level of satisfaction, the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot scale, 10 repetitive single heel rise, single leg hopping test, and ankle range of motion. Results: The AOFAS score increased from average 71.4 (50-87) to 96.4 (86-100). All patients were able to perform 10-repetitive single heel raise and single leg hopping at the latest follow up. No patient experienced wound complications and deep infection. Six patients were rated as 'excellent' and the other two as 'good'. Conclusion: Neglected chronic Achilles tendon ruptures could be successfully treated with careful selection of the reconstruction method according to the amount of defect gap. With an extensive defect, Achilles tendon allograft can be a good option when the reconstruction is not feasible otherwise.

• International Journal of Internet, Broadcasting and Communication
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• 제9권4호
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• pp.38-43
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• 2017

Sensor Networks (WSNs) can be defined as a self-configured and infrastructure-less wireless networks to monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants and to cooperatively pass their data through the network to a main location or base-station where the data can be observed and analyzed. Typically a wireless sensor network contains hundreds of thousands of sensor nodes. The sensor nodes can communicate among themselves using radio signals. A wireless sensor node is equipped with sensing and computing devices, radio transceivers and power components. The individual nodes in a wireless sensor network (WSN) are inherently resource constrained: they have limited processing speed, storage capacity, communication bandwidth and limited-battery power. At present time, most of the research on WSNs has concentrated on the design of energy- and computationally efficient algorithms and protocols In order to extend the network life-time, in this paper we are looking into a routing protocol, especially LEACH and LEACH-related protocol. LEACH protocol is a representative routing protocol and improves overall network energy efficiency by allowing all nodes to be selected to the cluster head evenly once in a periodic manner. In LEACH, in case of movement of sensor nodes, there is a problem that the data transmission success rate decreases. In order to overcome LEACH's nodes movements, LEACH-Mobile protocol had proposed. But energy consumption increased because it consumes more energy to recognize which nodes moves and re-transfer data. In this paper we propose the new routing protocol considering nodes' mobility. In order to simulate the proposed protocol, we make a scenario, nodes' movements randomly and compared with the LEACH-Mobile protocol.

• 대한인간공학회지
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• 제17권3호
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• pp.13-22
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• 1998

Aircraft and the three-dimensional environment in which they operate are not user-friendly for human beings. As a result, maintaining the proficiencies necessary to safely and efficiently fly an airplane are difficult, and costly. The physiological and emotional status of the human element remains crucial in maintaining safe performance by all crew members. In the study of Hagiwara et al.(1993). they called the physiological and emotional status of the human element into the human alertness or physiological activity and stress, fatigue, circadian rhythm, alcohol. smoking, and self-medication are known the major factors that deteriorate the human alertness. Accordingly. this paper deals with the quantitative and objective performance test based on tracking error and reaction time by means of the new computer test program into which the perception-motion system of human beings is applied. Throughout this experiment using performance test, the results suggest that performance capability in state of sleep deprivation 2 hours and alcoholic 0.05~0.06% in blood were more impaired than one in a normal state, and they further showed statistically significant differences between them, which were influenced by impairment factors of body regulation and pilot's grade. We also obtained the prediction value and the 95% confidence interval of tracking error and reaction time at the normal state for the purpose of distinguishing performance capability between the normal state and the abnormal state. And it is expected that the evaluation of human alertness using performance test will be applied to the quantitative assessment of an each pilot's realistic consciousness/attention, and will lead a flight commander to the accurate decision of mission approval prior to a flight.

• 한국기계가공학회지
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• 제19권5호
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• pp.21-26
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• 2020

A descending lifeline is the only self-escape fire apparatus for fire in high-rise buildings and is installed in most buildings according to fire-fighting law. However, it is difficult to properly use and quickly evacuate during an emergency due to its complex installation methods and procedures, even if users are pre-educated. In this paper, a new one-touch descending lifeline, which simplifies usage procedures and can be used regardless of whether users are educated, is proposed to solve the drawbacks of the conventional descending lifeline. All separate parts that require additional installation are initially assembled in a box, and the concept of a double square linkage is proposed to enable escape in a single motion of pushing the handle attached to the box. Three steps of kinematic design are explored to determine an appropriate configuration of double square linkage, and its dimensions are determined using Matlab and NX CAD software. The proposed all-in-one descending lifeline also follows the enforcement decree of the Fire Control Act, and its feasibility is verified through fabrication.

• 성인간호학회지
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• 제24권3호
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• pp.317-326
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• 2012

Purpose: The purpose of this study was to identify the effects of an exercise program on muscle strength, Activities of Daily Living (ADL), health perception, and depression among post-stroke elders. Methods: Nonequivalent control group design with pretest and posttest was used. A total of 23 post-stroke elders who met inclusion criteria were recruited. Muscle strength in upper and lower extremities, ADL, health perception, and self-rated symptoms of depression were measured. The exercise program consisted of deep breathing, range of motion, and muscle strengthening exercises using Thera-band, 30~40 min/day, three days a week, for 12 weeks. Results: Muscle strength of right shoulder (U=11.50, p=.001), right leg (U=13.50, p=.002), and health perception (U=24.00, p=.010) in the experimental group was significantly higher compared to the control group at 12 weeks of post-intervention. Depression scores were significantly lower in the experimental group compared to the control group at 6 weeks (U=28.00, p=.021), at 12 weeks (U=22.00, p=.006) of an exercise program. Conclusion: By applying this program, post-stroke elders showed increases in muscle strength and a decrease in depression as well as improvement of health perception. Further study is needed to verify the effects of the exercise program on cardiovascular physiologic variables through long-term follow-up.

• 대한안전경영과학회지
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• 제11권2호
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• pp.103-110
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• 2009

The purpose of this study is to suggest a proper tread of stairs using kinematic factors and moments of the lower-limb joints in the stair decent with the 3 different treads with boimechanical method in ergonomics. 9 subjects (body masses; $59.41{\pm}7.49$, $64.03{\pm}6.65$, $67.26:{\pm}7.58$, heights; $160.50{\pm}6.35$ ages; $31.22{\pm}2.99$; parity; $1.67{\pm}0.71$) participated in three experiments that were divided by physiological symptoms (the early (0-15 weeks), middle (16-27 weeks) and last (18-39 weeks). and they walked at self-selected pace on 4 staircases 3 trials. As extending the pregnancy period, cadence was shorter but cycle time were longer more and more. As extending treads of stair decent during pregnancy, speed, stride lengths and cycle time were increased. As extending the treads of stair decent, hip and ankle moments increased but knee moments decreased in sagittal plane. There were increasing or decreasing of moments by means of treads. These changes may account for relation between the treads of stair and moments in pregnant women. The main changes of pregnant women were joint moments and kinematic factors during pregnancy period because pregnancy makes them physical changes. It is possible that joints have connection with compensation each other to maximize stability and to control gait motion. In conclusion, we suggest that the tread of stair is longer than 26cm tread. and exercise programs to improve muscle activity were necessary where joint moments were small.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1446-1449
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• 1996

Thin films of diamond-like carbon(DLC) have been deposited using a magnetron plasma-enhanced chemical vapor deposition(PECVD) method with an rf(13.56 MHz) plasma of $C_{3}H_{8}$. From the Langmuir probe I-V characteristics, it can be observed that increasing the magnetic field yields an increase of the temperature($T_e$) and density($N_e$) of electron. At a magnetic field of 82 Gauss, the estimated values of $T_e$ and $N_e$ are approximately $1.5\;{\times}\;10^5$ K(13.5 eV) and $1.3\;{\times}\;10^{11}\;cm^{-3}$, respectively. Such a highly dense plasma can be attributed to the enhanced ionization caused by the cyclotron motion of electrons in the presence of a magnetic field. On the other hand, the negative dc self-bias voltage($-V_{sb}$) decreases with an increasing magnetic field, which is irrespective of gas pressure in the range of $1{\sim}7$ mTorr. This result is well explained by a theoretical model considering the variation of $T_e$. Deposition rates of DLC films increases with a magnetic field. This may be due to the increased mean free path of electrons in the magnetron plasma. Structures of DLC films are examined by using various techniques such as FTIR and Raman spectroscopy. Most of hydrocarbon bonds in DLC films prepared consist of $sp^3$ tetrahedral bonds. Increasing the rf power leads to an enhancement of cross-linking of carbon atoms in DLC films. At approximately 140 W, the maximum film density obtained is about 2.4 $g/cm^3$.

• 대한기계학회논문집A
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• 제38권8호
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• pp.837-848
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• 2014

본 논문에서는 보행이 불편한 노인들의 효과적인 자가 재활을 위한 보행 보조 로봇의 개발에 대해 연구하였다. 개발된 로봇의 주요 특징은 크게 유아보행기 및 전동휠체어 메커니즘을 융합한 안전성 및 운동성향상과 가변저항 및 스테레오 카메라를 이용한 정확한 보행 추종 제어 알고리즘으로 나눌 수 있다. 구체적으로, 유아보행기의 메커니즘을 적용하여 사용자가 보행 중 넘어지는 사고로부터 안전을 확보하는 동시에 다리근육의 부담을 줄여줄 수 있는 골반지지대를 설계하였으며, 전동휠체어와 같이 구동모터를 이용하여 사용자가 적은 힘으로도 로봇을 이동시킬 수 있도록 하였다. 다음으로, 골반지지대에 부착된 가변저항을 이용하여 사용자의 보행 의도 및 방향을 로봇이 자동적으로 판단하고 사용자를 추종할 수 있도록 하였으며, 스테레오 카메라를 이용한 사용자 하체모션분석 알고리즘으로부터 추종 반응속도와 정확성을 한층 높였다. 최종적으로, 단계적인 보행 보조 실험을 통해 개발된 로봇의 사용자 보행 추종 성능을 실험적으로 검증하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.489.2-489.2
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• 2014

The planar type flexible piezoelectric energy harvesters (PEH) based on PbZr0.52Ti0.48O3 (PZT) thin films on the flexible substrates are demonstrated to convert mechanical energy to electrical energy. The planar type energy harvesters have been realized, which have an electrode pair on the PZT thin films. The PZT thin films were deposited on double side polished sapphire substrates using conventional RF-magnetron sputtering. The PZT thin films on the sapphire substrates were transferred by PDMS stamp with laser lift-off (LLO) process. KrF excimer laser (wavelength: 248nm) were used for the LLO process. The PDMS stamp was attached to the top of the PZT thin films and the excimer laser induced onto back side of the sapphire substrate to detach the thin films. The detached thin films on the PDMS stamp transferred to adhesive layer coated on the flexible polyimide substrate. Structural properties of the PZT thin films were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). To measure piezoelectric power generation characteristics, Au/Cr inter digital electrode (IDE) was formed on the PZT thin films using the e-beam evaporation. The ferroelectric and piezoelectric properties were measured by a ferroelectric test system (Precision Premier-II) and piezoelectric force microscopy (PFM), respectively. The output signals of the flexible PEHs were evaluated by electrometer (6517A, Keithley). In the result, the transferred PZT thin films showed the ferroelectric and piezoelectric characteristics without electrical degradation and the fabricated flexible PEHs generated an AC-type output power electrical energy during periodically bending and releasing motion. We expect that the flexible PEHs based on laser transferred PZT thin film is able to be applied on self-powered electronic devices in wireless sensor networks technologies. Also, it has a lot of potential for high performance flexible piezoelectric energy harvester.