• 센서학회지
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• 제32권3호
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• pp.131-139
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• 2023

Ascorbic acid plays a crucial role in the regulation of neurotransmitters and enzymes in the central nervous system. Maintaining an optimal level of ascorbic acid, which is between 0.6-2 mg/dL, is vital for preventing oxidative stress and associated health conditions, such as cancer, diabetes, and liver disease. Therefore, the detection of ascorbic acid is of the utmost importance. Electrochemical sensing has gained significant attention among the various detection methods, owing to its simplicity, speed, affordability, high selectivity, and real-time analysis capabilities. However, conventional electrodes have poor signal response, which has led to the development of modified electrodes with better signal response and selectivity. Carbon nanotubes (CNTs) and their composites have emerged as promising materials for the electrochemical detection of ascorbic acid. CNTs possess unique mechanical, electrical, and chemical properties that depend on their structure, and their large surface area and excellent electron transport properties make them ideal candidates for electrochemical sensing. Recently, various CNT composites with different materials and nanoparticles have been studied to enhance the electrochemical detection of ascorbic acid. Therefore, this review aims to highlight the significance of CNTs and their composites for improving the sensitivity and selectivity of ascorbic acid detection. Specifically, it focuses on the use of CNTs and their composites in electrochemical sensing to revolutionize the detection of ascorbic acid and contribute to the prevention of oxidative stress-related health conditions. The potential benefits of this technology make it a promising area for future research and development.

• 천문학회보
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• 제46권2호
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• pp.75.2-76
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• 2021

MESSIER is a science satellite project to observe the Low Surface Brightness (LSB) sky at UV and optical wavelengths. The wide-field, optical system of MESSIER is optimized minimizing optical aberrations through the use of a Linear Astigmatism Free - Three Mirror System (LAF-TMS) combined with freeform mirrors. One of the key factors in observations of the LSB is the shape and spatial variability of the Point Spread Function (PSF) produced by scatterings and diffraction effects within the optical system and beyond (baffle). To assess the various factors affecting the PSF in this design, we use PhoSim, the Photon simulator, which is a fast photon Monte Carlo code designed to include all these effects, and also atmospheric effects (for ground-based telescopes) and phenomena occurring inside of the sensor. PhoSim provides very realistic simulations results and is suitable for simulations of very weak signals. Before the application to the MESSIER optics system, PhoSim had not been validated for confocal off-axis reflective optics (LAF-TMS). As a verification study for the LAF-TMS design, we apply Phosim sequentially. First, we use a single parabolic mirror system and compare the PSF results of the central field with the results from Zemax, CODE V, and the theoretical Airy pattern. We then test a confocal off-axis Cassegrain system and check PhoSim through cross-validation with CODE V. At the same time, we describe the shapes of the freeform mirrors with XY and Zernike polynomials. Finally, we will analyze the LAF-TMS design for the MESSIER optical system.

• 응용화학
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• 제15권2호
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• pp.113-116
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• 2011

A sensitive and selective determination method of Fe(II) ion by luminol-H₂O₂ system using a chelating reagent has been presented. A metal ion-chelating ligand complex such as Fe(II)-diethylenetriamine pentaacetic acid (DTPA) produced higher chemiluminescence (CL) intensity as well as longer lifetime in luminol-H₂O₂ system than metal exist as free ions. Furthermore, the catalytic activity of Cu(II) and Pb (II) complexes with chelating reagents in luminol-H₂O₂ system was lost since chelating reagents act as a masking agent although free Cu(II) and Pb(II) ions have high catalytic activity. On the optimized conditions, the calibration curve of Fe(II) ion was linear over the range from 1.0×10^-7 to 2.0×10^-5 M with correlation coefficient of 0.996. The detection limit was calculated to be 4.0×10^-8 M.

• 센서학회지
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• 제32권5호
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• pp.328-333
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• 2023

This study experimentally verified the etch rate of the SiO₂ sacrificial layer etching process with a single etch hole using vapor-phase hydrogen fluoride (VHF) etching. To fabricate small-sized polysilicon etch holes, both circular and triangular pattern masks were employed. Etch holes were fabricated in the polysilicon thin film on the SiO₂ sacrificial layer, and VHF etching was performed to release the polysilicon thin film. The lateral etch rate was measured for varying etch hole sizes and sacrificial layer thicknesses. Based on the measured results, we obtained an approximate equation for the etch rate as a function of the etch hole size and sacrificial layer thickness. The etch rates obtained in this study can be utilized to minimize structural damage caused by incomplete or excessive etching in sacrificial layer processes. In addition, the results of this study provide insights for optimizing sacrificial layer etching and properly designing the size and spacing of the etch holes. In the future, further research will be conducted to explore the formation of structures using chemical vapor deposition (CVD) processes to simultaneously seal etch hole and prevent adhesion owing to polysilicon film vibration.

• 한국운동역학회지
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• 제14권3호
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• pp.99-118
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• 2004

The aim of this study is to evaluate tennis shoes's plantar pressure distribution in tennis prayers and to determine the influence of the shoe on various tennis movements. When investigating the biomechanics of movement in tennis, one of the first things to do is to understand the movement patterns of the sport, specifically how these patterns relate to different tennis shoes. Once these patterns are understood, footwear company can design tennis shoes that match the individual needs of tennis players. Plantar pressure measurement is widely employed to study foot function, the mechanical pathogenesis for foot disease and as a diagnostic and outcome measurement tool for many performance. Measurements were taken of plantar pressure distribution across the foot and using F-Scan(Tekscan Inc.) systems respectively. The F-Scan system for dynamic in-shoe foot pressure measurements has enabled us to assess quantitatively the efficacy of different types of footwear in reducing foot pressures. The Tekscan F-Scan system consists of a flexible, 0.18mm thick sole-shape having 1260 pressure sensors, the sensor insole was trimmed to fit the subjects' right, left shoes. For this study 4 university male, high level tennis players were instructed to hit alternated forehand stroke, backhand stroke, forehand volley, backhand volley, smash, service movement in 4 different tennis shoes. 1. When impact in tennis movement, peak pressure distribution of landing foot displayed D>C>B>A, A displayed the best low pressure distribution. A style's tennis shoes will suggest prayer with high impact. If prayer with high impact feeling during pray in tennis wear A style, it will decrease injury, will have performance improvement. 2. When impact in tennis movement, plantar pattern of pressure distribution in landing foot displayed B>A>C>D in stability performance. During tennis, prayer want to stability movement suggest B style tennis shoes when tennis movement impact keep stability of human body. B style tennis shoes give performance improvement 3. When impact in tennis movement, plantar pattern of center of force(C.O.F.)trajectory in landing foot analyzed this : 1) When stroke movement and volley movement in tennis, prayer better to rearfoot movement. 2) when service movement, prayer midfoot strike movement. 3) when smash movement, prayer have forefoot strike movement.

• 천문학회보
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• 제40권1호
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• pp.54.3-54.3
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• 2015

To probe the star formation in local and early Universe, the NISS with a capability of imaging spectroscopy in the near-infrared is being developed by KASI. The main scientific targets are nearby galaxies, galaxy clusters, star-forming regions and low background regions. The off-axis optical design of the NISS with 15cm aperture was optimized to obtain a wide field of view (FoV) of $2deg.{\times}2deg.$ as well as a wide spectral coverage from 0.9 to $3.8{\mu}m$. The opto-mechanical structure was designed to be safe enough to endure in both the launching condition and the space environment. The dewar will operate $1k{\times}1k$ infrared sensor at 80K stage. The NISS will be launched in 2017 and explore the large areal near-infrared sky up to $200deg.^2$ in order to get both spatial and spectral information for astronomical objects. As an extension of the NISS, KASI is planning to participate in a new small space mission together with NASA. The promising candidate, SPHEREx (Spectro-Photometer for the History of the Universe Epoch of Reionization, and Ices Explorer) is an all-sky survey satellite designed to reveal the origin of the Universe and water in the planetary systems and to explore the evolution of galaxies. Though the survey concept is similar to that of the NISS, the SPHEREx will perform the first near-infrared all-sky imaging spectroscopic survey with the wider spectral range from 0.7 to $5{\mu}m$ and the wider FoV of $3.5deg.{\times}7deg.$ Here, we report the current status of the NISS and introduce new mission for the near-infrared imaging spectroscopic survey.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.375-375
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• 2012

Graphene is a sp2-hybridized carbon sheet with an atomic-level thickness and a wide range of graphene applications has been intensely investigated due to its unique electrical, optical, and mechanical properties. In particular, hybrid graphene structures combined with various nanomaterials have been studied in energy- and sensor-based applications due to the high conductivity, large surface area and enhanced reactivity of the nanostructures. Conventional metal-catalytic growth method, however, makes useful applications difficult since a transfer process, used to separate graphene from the metal substrate, should be required. Recently several papers have been published on direct graphene growth on the two dimensional planar substrates, but it is necessary to explore a direct growth of hierarchical nanostructures for the future graphene applications. In this study, uniform graphene layers were successfully synthesized on highly dense dielectric nanowires (NWs) without any external catalysts. We also demonstrated that the graphene morphology on NWs can be controlled by the growth parameters, such as temperature or partial pressure in chemical vapor deposition (CVD) system. This direct growth method can be readily applied to the fabrication of nanoscale graphene electrode with designed structures because a wide range of nanostructured template is available. In addition, we believe that the direct growth growth approach and morphological control of graphene are promising for the advanced graphene applications such as super capacitors or bio-sensors.

• 대한전자공학회논문지SP
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• 제47권6호
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• pp.107-116
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• 2010

스미어 현상은 CCD 센서의 전하 전달 과정에 기인한다. 정지 영상에서는 기계적 셔터와 같은 하드웨어적인 구조로 이를 제거하지만, 동영상에서는 수행 시간의 제약 등의 문제로 이러한 방식이 적용될 수 없다. 본 논문에서는 신호처리 관점에서 스미어 현상을 제거하여 정지 영상뿐만 아니라 동영상에도 적용이 가능한 스미어 제거 방식을 제안한다. 제안하는 방식은 CCD 센서의 모서리 부분에 존재하는 화소들의 집단인 광학암흑영역(optical black region)을 이용한다. 광학암흑영역은 실제로 빛의 영향을 받지 않아 상이 맺히지 않지만, 스미어가 발생할 경우 전하 전달에 의하여 스미어 신호가 저장된다. 따라서 제안하는 방식은 스미어 신호를 정확하게 추정하기 위해서 광학암흑영역에 발생한 신호로부터 스미어와 잡음에 의한 영향을 구분하고 잡음은 제거하면서 스미어 신호는 유지하는 과정을 선행하며, 이렇게 처리된 광학암흑영역 신호를 영상 전반에 빼주어 스미어 현상을 제거한다. 또한 스미어 현상에 의해 포화가 발생한 경우는 손실된 원 신호의 정보를 주변의 화소 값으로 대체하여 스미어 현상에 의한 시각적 열화를 개선한다. 실험 결과를 통해 제안하는 방법이 기존 방법에 비해 시각적인 면에서 뛰어난 결과를 보임을 확인할 수 있다.

• 한국화재소방학회논문지
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• 제31권3호
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• pp.63-72
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• 2017

본 논문에서는 저압용 10회로 분전반을 전기공업협동조합(KEMC) 2102-610 규정에 근거하여 제작하였다. 또한, 개발된 10회로 분전반의 특성 평가를 실시하여 안전성을 확보하고자 한다. 개발된 10회로 분전반은 내식성, 절연 재료의 특성, 자외선 복사의 내성, 기계적 충격 등에 적합하도록 설계되었다. 개발된 분전반은 외함의 보호 등급, 감전방지와 보호회로, 개폐 장치와 구성품, 내부 전기 회로와 연결부, 외부 도체의 단자, 절연 특성, 온도 상승 시험, 열저항 등이 적합하도록 제작하였다. 개발된 10회로 분전반은 단상 회로와 3상 회로 등으로 구분되어 있다. 분기된 각각의 차단기 부하측에 센서 모듈을 설치하여 부하의 전선로에서 발생되는 누설전류의 크기를 실시간 측정할 수 있다. 그리고 부하의 용도 및 목적 등에 따라 회로를 증설할 수 있고, 각각의 부하 상태 역시 실시간 부하 관리 및 점검이 가능하다. 개발된 10회로 분전반의 온도 상승 시험을 실시한 곳은 인입 접속부, 주회로 및 분기회로 모선, 모선지지물 등 18 개소이다. 온도가 가장 높게 측정된 곳은 분기회로 모선용 MCCB 전원측 접속부의 R-phase으로 $65.3^{\circ}C$, 부하측은 T-phase으로 $61.6^{\circ}C$로 기록되었다. 그리고 내열 실험 장치를 이용하여 MCCB를 $180^{\circ}C$에서 6시간 동안 열적 스트레스를 인가하였을 때 작동 손잡이의 변형이 확인되었고, 트립 상태로 이동한 것이 확인되었다.

• 전자공학회논문지
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• 제53권11호
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• pp.151-159
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• 2016

본 논문에서는 다량의 온수가 필요하지 않는 세면을 목적으로 개발된 세라믹 발열체 기반 비저장식 순간 전기온수기를 제안한다. 입력되는 물을 가열하여 온수로 출수시키는 히팅모듈은 유량센서를 이용하여 입력되는 물을 감지하고 세라믹 히팅 모듈을 동작시킨다. 히팅 모듈 내부는 분당 1.5리터로 입수되는 물의 온도 대비 약 $15^{\circ}C$정도로 가열된 온수로 입수 2초 내에 출수시키기 위해 1 path 유로로 설계하였고 또한 설계의 타당성을 검증하기 위해 히팅모듈 내부 물의 흐름과 온도변화에 대한 열유동해석을 수행하였다. 기본 설계를 기초로 내부에 막대형 세라믹 발열체 1개가 내장된 히팅모듈을 제작하였다. 히팅모듈 제작 후 3단계로 온도 세팅 기능을 가지는 온수기 시제품을 제작하였다. 제작된 시제품을 분당 1.5리터의 물을 공급하는 상수도관에 연결하고 출수되는 물의 온도 및 시간을 측정한 실험에서 물 공급 후 2초 후에 온수기 3단 기준으로 공급되는 물 온도 대비 $18.3^{\circ}C$로 가열된 온수를 출수할 수 있음을 확인하였다. 그리고 대기전력 1w 미만, 순간 전력도 일반가정에서의 허용범위를 넘지 않는다. 성능 측정 결과들을 통해 제안된 비저장식 순간 전기온수기가 겨울철 세면용으로 가정, 고속도로휴게소, 공장 등의 세면대에 적용이 가능함을 확인하였다.