• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.2
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• pp.235-241
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• 2018

In this study, total fluoride (TF) in commercial toothpastes for children in Korea was evaluated and compared with the fluoride concentration declared by the manufacturer (Declared F). Additionally, total soluble fluoride (TSF) was evaluated and compared with TF. Ten toothpastes were coded with letters to allow blind analysis. For evaluation of TF, each toothpaste was homogenized in deionized water. For evaluation of TSF, each toothpaste was centrifuged and then, the supernatant of the sample was evaluated. Fluoride concentrations were assessed using a fluoride electrode coupled to an ion analyzer. Only one toothpaste showed lower TF concentration than Declared F. In all toothpastes, TSF was similar to the TF.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.10
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• pp.1158-1165
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• 1988

In this paper, the polarization properties of spun fiber due to intrinsic birefringence and magneto-optic effects are theoretically analyzed and experimented. The degree of polarization which indicates the intrinsic birefrigence is measured over 0.818, and the variation of output polarization angle with input polarization angle is measured within 9$^{\circ}$. Compared with single mode fiber, spun fiber is found to have very excellent polarization-maintaining property. Implemented current measurement system using spun fiber can linearly measure the magnetic field up to 20,000 A/m generated by solenoid.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.292-292
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• 2013

최근, 자연의 기능성 표면을 모사하여 우리 생활에 응용하기 위한 연구가 활발하다. 초-발수 특성을 가지는 대표적인 예인 연꽃잎은 마이크로-나노 크기의 거친 미세돌기(papillae)를 가지고 있으며 그 위에 낮은 표면 에너지를 가지는 왁스(wax)가 발달 되어 항상 깨끗한 상태를 유지한다. 본 실험에서는 이를 모사하여 RIE (Reactive Ion Etching)방법을 이용하여 기판인 Poly silicon wafer를 Sf6가스를 사용하여 Metal mash로 거칠기를 만들어 주었고, RF-magnetron sputtering 장치를 사용하여 $6{\times}10^{-3}$ Torr의 진공도에서 낮은 표면에너지를 가지는 PTFE (polytetrafluoroethylene)를 증착하여 표면 구조와 발수특성에 대하여 조사하였다. SSME(Surface shape measurement equipment)측정결과 0.24~0.36 um RSa 값이 측정되었고, 12 uL의 Di-water로 접촉각을 측정 한 결과 RIE 10분 처리를 한 기판 위에 PTFE를 3분 증착하였을 때 가장 높은 $153^{\circ}$의 초-발수 특성이 나타났으며, 4주의 시간이 지났을 때에도 접촉각이 유지가 되었다. XPS 측정결과 초-발수 표면에서 나타나는 CF2와 CF3 피크 값이 측정되었다. Reactive Ion Etching을 이용한 PTFE 발수 특성은 방수, 스마트 윈도우, 자가세정(Self-Cleaning), 디스플레이 표시장치, 김서림 방지(Anti-Fogging), 대전방지 코팅 등에 다각적으로 응용 가능할 것이라 사료된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.149.2-149.2
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• 2013

친 환경적 소재인 ETFE (Ethylene Tetra Fluoro Ethylene)는 내화학성과 단열성을 가지며 탁월한 빛투과성, 자정효과 및 초경량 소재의 특성을 가진 열가소성 불소수지로서 서울시 신청사, Water Cube라고 많이 알려진 베이징 올림픽 수영 경기장 같은 대형 건축물의 외벽에 사용될 만큼 최근 세계 각국의 건축가들에게 각광을 받고 있다. 본 실험에서는 영구자석을 이용한 고밀도 플라즈마로 높은 점착성과, 균일한 박막 및 대면적 공정이 가능한 RF-magnetron sputtering방법으로 기판인 Slide glass위에 ETFE를 증착하여 접촉각의 변화와 구조적 및 광학적 특성에 대하여 측정하였다. 접촉각 측정결과 35w에서 $15^{\circ}$ 이하의 친수 특성을 나타내었고, 자외선 파장에서의 투과율 측정 결과 87% 이상의 높은 투과율을 나타내었다. AFM (Atomic Force Microscope) 측정결과 35 W에서 1.6 nm의 RMS (Root mean square)값이 측정 되었다. ETFE 특성은 비가 오면 자동으로 이물질이 씻겨 내려 주기적으로 청소를 해줘야하는 유리보다 유지관리비가 적게 될 것으로 사료되고, 높은 자외선 투과율을 보임으로 온실에서 균형 잡힌 식물 성장을 위한 화학약품의 소모를 줄여 줄 것으로 사료된다.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.4
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• pp.28-35
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• 2021

Infrared (IR) stealth technology to protect aircraft from heat-tracking missiles is a very important factor in the development of military aircraft. In this study, the intensities of signal generation were compared by observing the IR signals generated from the plumes of the engine and identifying them for each measurement angle. To simulate a jet engine applied to an actual aircraft, a small turbojet engine was constructed, the infrared signal characteristics for each wavelength were identified according to the measurement angle, and the total infrared radiance was derived by integrating the signal for each wavelength. Through this study, we intend to present basic data for improving the infrared stealth performance of aircraft.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.303-303
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• 2023

실용적인 표면영상유속계를 만들기 위해서는 적절한 하드웨어와 소프트웨어로 시스템을 구성해야 한다. 이를 위해서 본 연구에서는 하드웨어로 CCTV를 선택하고, 초음파 수위계를 이용하여 수위를 지속적으로 읽어들이도록 구성하였다. 한편, 소프트웨어적으로는 11변수 투영법을 적용하여 변화하는 수위에 따라 정확한 측정점을 재구성하도록 하고, 아울러 각 측정점에서 주흐름방향으로 정확한 시공간영상을 작성하고, 이 시공간영상(spatio-temporal image)들을 분석하였다. 그결과, 5분 간격으로 촬영된 1분 길이의 영상을 지속적으로 촬영하고 분석하여 유량을 산정하는 표면영상유속계측 시스템을 구축하였다. 본고에서는 이러한 소프트웨어 개선방향중 하나인 주흐름방향의 시공간영상 작성법을 소개한다. 먼저, 11변수 투영법을 이용하여 하천의 표면영상에 대한 좌표변환계수를 산정하였다. 그리고 이 좌표변환계수를 이용하여, 하천의 수위변화에 따라 표면영상내의 측정점이 적절히 수정될 수 있도록 하였다. 그 다음 이 측정점에서 측정횡단면과 수직이 되는 방향을 선정하고, 이 방향이 영상내에서 하천 측정횡단면과 수직인 방향, 즉 주흐름방향이 되도록 하였다. 촬영된 1분간의 동영상의 각 측정점 위치에서 잘라낸 시공간체적(spatio-temporal image volume)에서 주흐름방향의 시공간영상을 잘라내고 이를 상호상관법이나 고속푸리에변환을 이용하여 분석하였다. 이 때 만들어진 시공간영상은 주흐름방향과 정확하게 일치하여, 기존의 표면영상유속계의 문제이던, 일부 측정점의 유속벡터가 주흐름방향과 일치하지 않던 문제를 해결할 수 있었다. 개발된 방법으로 표면영상유속계를 제작하여 인수천에 시험 설치하고 호우 사상에 대해 검토한 결과 정확하고 신속하며 연속적인 유량측정이 가능하였다.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.6 no.2
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• pp.43-48
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• 2012

In this paper, we present the method of gait phases detection using multi biomedical signals during normal gait. Electromyogram(EMG) signals, muscle of thigh angle measurement device and resistive sensors are used for experiments. We implemented a test targeting five adult male and identified the pattern of EMG signal of normal gait. For acquiring the EMG signal, subjects attached surface Ag/AgCl electrodes to quadriceps femoris, biceps femoris, tibialis anterior and gastrocnemius medialis. Resistance sensors are attached to the heel toe and soles of the each feet for measuring attachment state of between feet and ground. Infrared sensors are attached on the thigh and thigh angle measurement device has the range from flection 25 degrees to extension 20 degrees. The results of this paper, The stance and swing phase could be confirmed during the normal gait and be classified in detail the eight steps.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.47-54
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• 2013

In this paper, we present an inertial sensor-based motion capturing system to measure and analyze whole body movements. This system implements a wireless AHRS(attitude heading reference system) we developed using a combination of rate gyroscope, accelerometer and magnetometer sensor signals. Several AHRS modules mounted on segments of the patient's body provide the quaternions representing the patient segments's orientation in space. We performed 3D motion capture using the quaternion data calculated. And a method is also proposed for calculating three-dimensional inter-segment joint angle which is an important bio-mechanical measure for a variety of applications related to rehabilitation. To evaluate the performance of our AHRS module, the Vicon motion capture system, which offers millimeter resolution of 3D spatial displacements and orientations, is used as a reference. The evaluation resulted in a RMSE of 2.56 degree. The results suggest that our system will provide an in-depth insight into the effectiveness, appropriate level of care, and feedback of the rehabilitation process by performing real-time limbs or gait analysis during the post-stroke recovery process.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.95-102
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• 2016

Geomagnetic sensors are widely utilized for sensing heading direction of quadrotors. However, measurement from a geomagnetic sensor is easily corrupted by environmental magnetic field interference and roll/pitch directional motion. In this paper, a measurement method of a quadrotor heading direction is proposed for application to yaw attitude control. In order to eliminate roll/pitch directional motion effect, the geomagnetic sensor data is compensated using the roll/pitch angles measured for stabilization control. In addition, yaw-directional angular velocity data from a gyroscope sensor is fused with the geomagnetic sensor data using a complementary filter which is a simple and intuitive sensor fusion method. The proposed method is applied to experiments, and the results are presented to prove validity and effectiveness of the proposed method.

• The Journal of Korean Academy of Sensory Integration
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• v.14 no.1
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• pp.1-8
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• 2016

Objective : The purpose of this study was to determine the reliability of Test of Playfulness (ToP) in Attention Deficit Hyperactivity Disorder (ADHD) children. Methods : Twenty ADHD children participated in this study. To determine inter-rater reliability, two raters was evaluated by Test of Playfulness scores and analyzed Kappa coefficient and total agreement and intraclass correlation coefficient (ICC). Results : Total agreement was the range of 75%~95% and the Kappa coefficients was the range of. 45~1.00. Analyzing inter-rater reliability by ICC showed very high reliability: Intrinsic motivation was .96, internal control was .98, suspension of reality was .90, framing was .98, total score was .99. Conclusion : A reliability of Test of Playflness of children with ADHD showed that high. On the basis of this study, it will provide availability for clinical evaluation of children with ADHD, and basic study on the play of children with ADHD.