Single Magnetic Bead Detection in a Microfluidic Chip Using Planar Hall Effect Sensor

Hyuntai Kim,Venu Reddy,Kun Woo Kim,Ilgyo Jeong,Xing Hao Hu,CheolGi Kim 한국자기학회 2014 Journal of Magnetics Vol.19 No.1

In this study, we fabricate an integrated microfluidic chip with a planar Hall effect (PHE) sensor for single magnetic bead detection. The PHE sensor was constructed with a junction size of 10 μm × 10 μm using a trilayer structure of Ta(3 nm)/NiFe(10 nm)/Cu(1.2 nm)/IrMn(10 nm)/Ta(3 nm). The sensitivity of the PHE sensor was 19.86 μV/Oe. A diameter of 8.18 μm magnetic beads was used, of which the saturation magnetization was ~2.1 emu/g. The magnetic susceptibility χ of these magnetic beads was calculated to be~0.14. The diluted magnetic beads solution was introduced to the microfluidic channel attributing a single bead flow and simultaneously the PHE sensor voltage was measured to be 0.35 μV. The integrated microchip was able to detect a magnetic moment of 1.98 × 10<SUP>?10</SUP> emu.

Corrugation-assisted metal-coated angled fiber facet for wavelength-dependent off-axis directional beaming

Kim, Hyuntai,An, Haechan,Kim, Jinseob,Lee, Seungsu,Park, Kyoungyoon,Lee, Seungjong,Hong, Seungsoo,Vazquez-Zuniga, Luis Alonso,Lee, Seung-Yeol,Lee, Byoungho,Jeong, Yoonchan The Optical Society 2017 Optics express Vol.25 No.7

Simple and reliable light launch from a conventional single-mode fiber into a helical-core fiber through an adiabatically tapered splice.

Kim, Hyuntai,Kim, Jongki,Jung, Yongmin,Vazquez-Zuniga, Luis Alonso,Lee, Seung Jong,Choi, Geunchang,Oh, Kyunghwan,Wang, Pu,Clarkson, W A,Jeong, Yoonchan Optical Society of America 2012 Optics express Vol.20 No.23

<P>We propose a simple and efficient light launch scheme for a helical-core fiber (HCF) by using an adiabatically tapered splice technique, through which we overcome its inherent difficulty with light launch owing to the large lateral offset and angular tilt of its core. We experimentally demonstrate single-mode excitation in the HCF in this configuration, which yields the coupling efficiency of around -5.9 dB (26%) for a ~1.1-μm light input when the splice joint is tapered down to 30 μm in diameter. To our knowledge, this is the first proof-of-principle report on the fusion-splice coupling between an HCF and a conventional single-mode fiber.</P>

Theoretical study on the generation of a low-noise plasmonic hotspot by means of a trench-assisted circular nano-slit.

Kim, Hyuntai,Lee, Seung-Yeol,Koo, Sukmo,Kim, Jinseob,Park, Kyoungyoon,Lee, Dongyeul,Vazquez-Zuniga, Luis Alonso,Park, Namkyoo,Lee, Byoungho,Jeong, Yoonchan Optical Society of America 2014 Optics express Vol.22 No.22

<P>We propose a novel trench-assisted circular metal nano-slit (CMNS) structure implementable on a fiber platform for the generation of a low-noise cylindrical surface plasmon (CSP) hotspot. We design trench structures based on a multi-pole cancellation method in order that a converging surface plasmon signal is well separated from co-propagating non-confined diffracted light (NCDL) at the hotspot location. In fact, the secondary radiation by the quasi-pole oscillation at the edge of the trench cancels the primary NCDL, thereby enhancing the signal-to-noise ratio (SNR) of the CSP hotspot. In particular, we investigate two types of trench structures: a rectangular-trench (RT) structure and an asymmetric-parabolic-trench (APT) structure, which are considered for the sake of the simplicity of fabrication and of the maximal enhancement of the SNR, respectively. In comparison with a conventional CMNS having no trenches, we highlight that the mean SNR of the CSP hotspot is enhanced by 6.97 and 11.89 dB in case of the optimized RT and APT CMNSs, respectively. The proposed schemes are expected to be useful for increasing the SNR of plasmonic devices that are interfered by NCDL, such as various types of nano-slits for generating high-resolution plasmonic signals, for example.</P>

Theoretical and Numerical Study of Cylindrical-vector-mode Radiation Characteristics in Periodic Metallic Annular Slits and Their Applications

Hyuntai Kim,Yoonchan Jeong 한국광학회 2018 Current Optics and Photonics Vol.2 No.5

We investigate the radiation characteristics of radially polarized light and azimuthally polarized light through plasmonic subwavelength-scale annular slit (PSAS) structures, by means of both theoretical and numerical methods. Effective-medium theory was utilized to analyze the characteristics of PSAS structures, and the corresponding results showed that PSAS structures can function as a metallic medium for azimuthally polarized light, or as a low-loss dielectric medium for radially polarized light. Numerical calculations based on the finite-element method were also performed, to verify the theoretical analyses. It turned out that the numerical results supported the theoretical results. Moreover, we exploited the PSAS structures in novel nanophotonic elements with dual functionalities that could selectively focus or pass/block incident light, depending on its polarization state. For example, if PSAS structures were implemented in the dielectric region of a metallic Fresnel zone plate, the modified zone plate could function as a blocking element to azimuthally polarized light, yet as a focusing element to radially polarized light. On the contrary, if PSAS structures were implemented in the metallic region of a metallic Fresnel zone plate (i.e. the inverted form of the former), it could function as a focusing element to azimuthally polarized light, yet as a simple transparent element to radially polarized light.

Metallic Fresnel zone plate implemented on an optical fiber facet for super-variable focusing of light

Kim, Hyuntai,Kim, Jinseob,An, Haechan,Lee, Yohan,Lee, Gun-yeal,Na, Jeongkyun,Park, Kyoungyoon,Lee, Seungjong,Lee, Seung-Yeol,Lee, Byoungho,Jeong, Yoonchan The Optical Society 2017 Optics express Vol.25 No.24

비굴착 지하배수암거 형태별 지하배수 성능 비교분석

김현태 ( Kim Hyuntai ),유전용 ( Ryu Jeonyong ),정기열 ( Jung Kiyuol ),서동욱 ( Seo Donguk ) 한국농공학회 2018 한국농공학회논문집 Vol.60 No.6

In this study, subsurface discharge performance has been studied through theoretical seepage analysis on four types of culverts that can be installed under the condition of non-excavation, such as ⓐperforated pipe(Φ50mm), ⓑperforated pipe+horizontal mat (B50cm) ⓒperforated pipe+horizontal mat+vertical gravel(B<10cm), ⓓperforated pipe+vertical gravel(B<10cm), and existing typical type ⓔperforated pipe with gravel (B40, h=40cm) which can be installed by excavation. The analysis results were as follows. i) Subsurface discharge performance per unit (m) was ⓐtype 56%, ⓑ 91%, ⓒ 96%, ⓓ 76%, respectively, lower than the value of ⓔculvert. ii) However, considering that non-excavation culvert can be installed at a spacing of 5m with the installation cost of the existing excavation culvert at the interval of 10m, it was analyzed that unit subsurface discharge(q) of ⓐ20.2mm/day(110%), ⓑ32.8(178%), ⓒ34.6(188%) ⓓ27.5(149%) in the four types of non-excavation culvert installed at intervals of 5m under the condition of k=10^-4cm/s was much larger than the amount of ⓔtype 18.5(100%), existing excavation culvert installed at 10m interval. iii) Through the test construction, peak subsurface drainage discharge(q_p) was 38.4mm/day, which is larger than the value of design criteria and confirmed that it satisfies the analysis results as well. iv) In particular, it was evaluated that ⓑperforated pipe+horizontal mat(B50cm) are low cost, high efficiency subsurface drainage culvert type with sufficient drainage performance(178%).

古典醫書에 나타난 導引氣功 方法에 대한 硏究

김현태(Hyuntai Kim),한창현(Changhyun Han),이상남(Sangnam Lee),박지하(Jiha Park) 한국한의학연구원 2009 한국한의학연구원논문집 Vol.15 No.2

Objectives : Because of emphasizing a side of preventive medicine in the oriental medicine, an interest in Doinqigong (導引氣功: Physical and breathing exercise) has been elated recently. But, it has a limited sphere of application in the present south korea. Therefore we would like to bring out its sphere of application and detailed method in the oriental medicine classics. Method : We have researched theories and methods of Doinqigong in the Junghwaeujeon(中華醫典: Oriental medicine classic collections) DB according to below the procedure. (1) Making a related words list: We have used existing study of Doinqigong to make a list. It has been connected with Doinqigong. It includes not only technical terms, but also general terms. (2) Searching sentences: We have searched sentence that contain terms related with Doinqigong in the Junghwaeujeon DB. (3) Analysis of related sentences: We have searched and classified sentence by theory and method. Result : Results & Conclusion : (1) The total number of oriental medicine classics connected with Doinqigong is twelve. (2) The methods of Doinqigong have classified into three large groups: They are the Doinqigong for preservationing of good health, the Doinqigong for curing disease and the Doinqigong for internal organs and channels. (3) The number of Doinqigong for preservationing of good health in the seven oriental medicine classics is about ten. For example, the Okeumhi(五禽戱: Five animal's dance), the Paldangeum(八段錦: Eight motions of qigong) and so on. The number of oriental medicine classics connected with Doinqigong for curing disease is seven. They contain internal diseases, surgical diseases, diseases of five sensory organs and various diseases in the order of their frequency. The Doinqigong for internal organs and channels is only the Yookjageul(六字訣: Six sound's treatment).

밭작물 논 재배 확대를 위한 무굴착 암거배수 기술 개발

김현태 ( Hyuntai Kim ),정기열 ( Kiyuol Jung ),이상훈 ( Sanghun Lee ),유전용 ( Jeonyong Ryu ) 한국농공학회 2017 한국농공학회 학술대회초록집 Vol.2017 No.-

농업환경변화를 보면 농가소득이 벼보다 밭작물이 높기 때문에 기존 논에서 밭 작물재배를 원하는 농가가 많다. 하지만 저습답은 지하수위와 함수비가 높아 작물이 습해를 입기 때문에 밭작물재배에 어려움이 많다. 저습답에서 밭작물재배를 위하여, 지하암거와 심토파쇄 등의 보조공법이 적용되고 있으나, 기존 공법은 공사비가 높고, 지하배수효과가 낮은 문제가 있어, 저습답 농지범용화를 위하여 저비용 고효율 지하암거공법의 개발·도입이 필요하다. 본 연구에서 무굴착으로 시공이 가능한 암거모양별 지하배수성능을 분석하고, 공사비를 비교하여, 저비용 고효율 무굴착 지하암거공법을 제안하고, 저습답에 시험시공을 통하여 다음과 같은 결론을 얻었다. ① 무굴착시공이 가능한 ⓐ 유공관암거, ⓑ 유공관+수평필터매트(폭50cm) 암거는 단위m당 배수량은 기존 ⓒ 유공관+자갈소수재(30^*40cm)암거의 ⓐ 54%, ⓑ 92%로 적으나, m당공사비가 1/3로 기존암거를 10m간격으로 설치하는 것보다 ⓑ 유공관+수평매트암거를 5m간격으로 설치하면 공사비는 70%이나, 배수효과는 175%로 저비용 고효율 지하암거공법으로 평가·제안되었다. ② 이 결과를 바탕으로 미사질양토 저습답에 지하암거 시험시공결과, ⓒ 기존공법(7m간격)보다 ⓑ 무굴착 유공관+수평필터매트 암거(3, 5m간격)가 공사비도 적으면서, 지하수위 상승이 훨씬 적고, 하강도 훨씬 빠른 결과를 보이고 있다. ③ 토양함수비도 ⓒ 기존공법(7m간격)보다 ⓑ 무굴착 암거(3, 5m간격)가 함수비 상승도 적으면서 빠르게 작물생육의 최적함수비 상태로 되는, 훨씬 좋은 결과를 보였다. ④ 콩 시험재배결과 무암거 경구보다 기존 암거공법과 무굴착 암거설치경구가 작황이 훨씬 좋은 것으로 볼 때, 공사비가 저렴한 ⓑ 무굴착암거공법이 저습답 농지범용화에 적용이 가능한 저비용 고효율 공법으로 확인되었다. ⑤ 그리고 100^*100m의 대구획의 저습답은 규모화와 범용화 영농의 큰 장점을 가지고 있으나, 경사가 거의 없는 평지로 집중강우 시 포장 내 지표배수가 잘되지 않아, 이를 해결하기 위한 연구도 함께 필요하다는 결론을 얻었다.

저습답 농지범용화을 위한 저비용 지하배수촉진 방안

김현태 ( Hyuntai Kim ),박수용 ( Sooyong Park ),진선영 ( Sunyoung Jin ),김영화 ( Younghwa Kim ) 한국농공학회 2013 한국농공학회 학술대회초록집 Vol.2013 No.-

농업환경변화를 보면 농가소득이 벼(약 5백만원/ha)보다 밭작물이 2∼10배 이상 높기 때문에 농가들이 기존 논에서도 밭 작물재배를 희망하고 있는 농가가 많다. 기존 논 중에서 밭으로 쉽게 사용할 수 있는 조건의 농경지는 농민들이 이미 밭으로 활용하고 있는 실정이다. 그러나 저습답과 간척지의 농지는 밭으로 사용하기가 쉽지 않아 농가들이 밭작물재배가 가능한 농지범용화사업을 희망하고 있다. 저습답은 우기 시 습해의 문제가 있어 밭농사가 불가능한 실정이다. 이들 문제를 해결하기 위한 연구와 사업이 많이 시도되었으나, 개선효과가 낮고 공사비가 높아 실용성이 부족한 실정이다. 본 연구에서 저습답의 지하 침튜류 수치해석을 통해 흙속에 물의 이동특성을 분석하고, 저비용이면서 실용성 있는 지하배수촉진방안을 제시하고자 하였다. 지하암거와 무암거 조건에 대한 지하침투류해석 및 분석결과 ① 4m간격의 지하암거설치 시 무암거보다 지하배수량이 30~300배 이상 증가하는 것으로 분석되었으며, ② 단위면적당 지하배수량에 미치는 지하암거 직경의 크기의 영향은 매우 적으며, ③ 유공암거+수평필터(폭50cm, 100cm) 설치 시 유공암거만 설치한 것보다 배수량이 2배로 증가하는 매우 유용한 방안이며, ④ 원형유공관 만을 지하암거로 설치 시 암거설치간격은 3m이내, 유공관+수평필터(폭50, 100cm) 지하암거설치 시는 암거설치간격을 4~6m까지 가능한 것으로 분석되었다. ⑤ 저습답 흙의 투수계수가 k=1×10^-4cm/s 이상인 농경지에서는 지하암거설치로 우기에 습해방지효과가 있으나, k=1×10^-4cm/s 이하인 농경지에서는 지하암거설치만으로 습해방지가 불가능하므로 흙의 투수성을 증가시키는 방안이 필요하며. ⑥ 지하암거설치공사비를 저비용으로 하기 위하여 비굴착식 지하암거(유공관+수평필터) 설치장비와 공법의 적용이 필요하다는 결론을 얻었다.