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A study on various phase-shifted fiber grating realization methods
Park, Dongwook Research Institute of Science and Technology HONGI 2005 Hongik Journal of Science and Technology Vol.9 No.-
We analyze the spectral characteristics of the various types of phase-shifted fiber Bragg gratings that can be realized by controlling the UV exposure during the grating formation process. In particular, their reflection spectra are computed and compared against those of the ideal discrete phase-shift version.
초음파 센서를 이용한 차량 주차공간 탐색에서의 연석 감지 알고리즘
김수용(Suyong Kim),이동욱(Dongwook Lee),박성훈(Sunghoon Park),권재희(Jaehee Kwon) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
Recently many automobile companies are developing parking assist system as it improves the convenience of drivers. Among several types of parking assistance system, the method using ultrasonic sensors for detecting parking space is widely used because of its low cost and usefulness. In order to detect the parking space, the parking space detection algorithm provides the width and the length of the parking space using long range ultrasonic sensor. In this paper, to detect the accurate parking space with the curbstone, the curbstone detection algorithm is proposed. The performances of the proposed algorithm are verified and evaluated by experiments.
Park,Joosung,Park,Dongwook,Park,Seunghyun,Jung,Kapyull,Park,Jungsun,Hwang,Taiyoung,Jung,Gyungwoo,Choi,Kyeongsook,Kim,Yangho,Kim,Hyojin,Moon,Younghahn,Kim,Joonyoun 동아대학교 부설 산업의학연구소 1997 산업의학연구소 논총 Vol.- No.3
Objectives The purpose of this study was to describe hematopoietic and reproductive hazards of Korean electronic workers exposed to solvents containing 2-bromopropane. Methods Detailed medical and occupational histories were taken and thorough physical examinations with clinical laboratory tests were done for 33 workers (8 men and 25 women). Previous and present exposure was investigated in detail by industrial hygienists. Results Of the 25 female workers, 16 were shown to have secondary amenorrhea with high follicle-stimulating hormone levels, normal prolactin levels, and hot flashes. A total of eight workers with amenorrhea concurrently showed findings of pancytopenia. Among eight male workers, two showed azoospermia and another four showed some degree of oligospermia (normal >20 million·??) or reduced sperm motility (normal >50%). The bone marrow effects and the testis or ovarian failure was shown to be the main health hazards in this workplace. Except for the cleaning solution containing 97.4% 2-bromopropane, no other known physical or chemical agents could be identified as responsible for the gonadal and bone marrow effects, including ionizing radiation, lead, ethylene glycol ether and its acetates, benzene, and dibromochloropropane. Conclusions No previous studies have reported human toxicity for 2-bromopropane, but the results of this study lead to the tentative conclusion that the causal agent for the gonadal and bone marrow effects among the workers might be 2-bromopropane.
( Dongwook Lee ),( Jang Hun Kim ),( Dong-hyuk Park ),( Shin-hyuk Kang ),( Kyung-jae Park ) 대한뇌종양학회·대한신경종양학회·대한소아뇌종양학회 2023 Brain Tumor Research and Treatment Vol.11 No.4
Recurrence of Rathke’s cleft cysts (RCC) following surgery is not uncommon. We present a 33-yearold male patient with chronic headache and visual disturbances whose MRI showed mostly cystic, suprasellar mass with peripheral enhancement. Endoscopic extended transsphenoidal approach and tumor resection was performed and RCC was pathologically confirmed postoperatively. Early recurrence was first suspected at 3 months following surgery, and his serial MRIs showed a recurred mass without associated clinical symptoms. Upon further histopathological study, extensive squamous metaplasia and high Ki-67 were seen. Also, in this study, we discuss important factors associated with cyst recurrence following surgery.
A Study on the Dispersion of Long-Period Fiber Grating
Park,Dongwook,Hwang,Joon Hwan Research Institute for Science & Technology HONG- 1999 Hongik Journal of Science and Technology Vol.3 No.-
The dispersion characteristics and intensity spectra of uniform and phase-shifted long-period fiber gratings were investigated. We derived the solution of the coupled mode equations for the long period fiber grating and applied it along with the transfer matrix method (TMM) to calculate the wavelength-dependent variations of the group delay and the transmittance of the gratings.
Park, Kwangjin,Kim, Juyong,Park, Jun-Ho,Hwang, Yunil,Han, Dongwook Elsevier 2018 Journal of Power Sources Vol.408 No.-
<P><B>Abstract</B></P> <P>We describe a novel synchronous surface tailoring to form thin and uniform carbon coating layers and simultaneously induce an <I>in-situ</I> phase transition from a layered to spinel-like phase on the surfaces of Li-rich layered oxide (LLOs) particles by the thermal decomposition of 2,3-dihydroxynaphthalene (DN). The Li<SUB>2</SUB>MnO<SUB>3</SUB> component in pristine LLO is not affected during carbon coating, but the coordination numbers of the Co ions and the CoO bonds in the LiT<SUB>M</SUB>O<SUB>2</SUB> phase are diminished during carbon coating, implying that the formation of a spinel-like phase in LLO after carbon coating begins at the LiT<SUB>M</SUB>O<SUB>2</SUB> with little variation in the Li<SUB>2</SUB>MnO<SUB>3</SUB>. As a result, the optimized DN (0.2 wt%)-coated LLO cathode material shows superb electrochemical properties owing to the formation of uniform carbon coating layers and the layered-to spinel-phase transition on the surfaces of the LLO particles, which improves the surface stability, electronic conductivity, and Li-ion kinetics in the LLO.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel 2,3-dihydroxynaphthalene (DN)-coated Li-rich layered oxide was developed. </LI> <LI> Thin and uniform surface carbon layers were formed by the thermal decomposition of DN. </LI> <LI> An <I>in-situ</I> phase transition from a layered to spinel-like phase was observed on the surface. </LI> <LI> The synchronous surface tailoring improved the kinetics and surface stability of the cathode. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
조류발전용 1.2MW 권선형유도발전기 제어를 위한 전력변환장치 개발
박정우(Park, Jungwoo),이기욱(Lee, Kiwook),김동욱(Kim, Dongwook),염기대(Yum, Kidai),이광수(Lee, Kwangsoo),박진순(Park, Jinsoon) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06
국내에서 대체에너지 공급 비율을 보면 청정에너지로 분류할 수 있는 태양열에너지, 태양 광 에너지, 풍력에너지를 모두 합하여 대체에너지의 10%이하이며, 대체에너지 비율의 90% 이상을 폐기물로부터 얻은 에너지가 차지하고 있는 실정이다. 신재생에너지원에는 여러 종류가 있지만 해양에너지원에 대해 대상을 설정하고 이에 대한 부존량을 살펴보면 진도 주변의 해역에서 조류발전 부존량이 약 362만 kW가 되며, 시화호와 새만금 등지에서의 조력발전 부존량이 650만 kW, 동해안 후포 연안을 비롯한 파력발전 부존량이 20만kW가 되는 것으로 알려져 있다. 이에 따라 해양에너지를 실용화하기 위한 연구가 국내외에서 연구되고 있다. 본 논문은 권선형유도발전기를 갖는 조류발전 시스템을 대상으로 연구한 결과로 권선형유도발전기를 제어하기 위한 전력변환장치 개발과 관련한 내용이다. 신재생에너지원이 발전 단가 측면에서 경제성을 갖기 위해서 발전기 용량은 5MW 급까지 대용량화되어 있는 단계이지만 국내에서는 아직 MW급 이상이 되는 권선형 유도발전기와 권선형 유도발전기를 제어하는 전력변환장치에 대한 연구 실적이 없는 상황이다 이에 본 논문에서는 1MW급의 권선형유도발전기에 대한 개발 사례를 소개하면서 유효전력제어, 역률제어, 계통연계방법, 그리고 운전 속도에 따라 변동되는 회전자측에서의 피상전력 특성 등을 제시하고자 한다.
Han, Dongwook,Park, Kwangjin,Park, Jun-Ho,Yun, Dong-Jin,Son, You-Hwan THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.68 No.-
<P><B>Abstract</B></P> <P>We report the discovery of Li-rich Li<SUB>1+x</SUB>[(Ni<SUB>0.225</SUB>Co<SUB>0.15</SUB>Mn<SUB>0.625</SUB>)<SUB>1−y</SUB>V<SUB>y</SUB>]O<SUB>2</SUB> as a cathode material for rechargeable lithium-ion batteries in which a small amount of tetravalent vanadium (V<SUP>4+</SUP>) is selectively and completely incorporated into the manganese sites in the lattice structure. The unwanted oxidation of vanadium to form a V<SUB>2</SUB>O<SUB>5</SUB>-like secondary phase during high-temperature crystallization is prevented by uniformly dispersing the vanadium ions in coprecipitated [(Ni<SUB>0.225</SUB>Co<SUB>0.15</SUB>Mn<SUB>0.625</SUB>)<SUB>1−y</SUB>V<SUB>y</SUB>](OH)<SUB>2</SUB> particles. Upon doping with V<SUP>4+</SUP> ions, the initial discharge capacity (>275mAhg<SUP>−1</SUP>), capacity retention, and voltage decay characteristics of the Li-rich layered oxides are improved significantly in comparison with those of the conventional undoped counterpart.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>