초소형 전자 렌즈의 전자 광학적 분석

김호섭,김대욱,김영철,최상국,김대용,Kim, Ho-Seob,Kim, Dae-Wook,Kim, Young-Chul,Choi, Sang-Kuk,Kim, Dae-Yong 한국광학회 2003 한국광학회지 Vol.14 No.2

FCM(Fast moving least square reproducing kernel point collocation method) 방식의 simulation tool을 이용하여 전기장으로 구동되는 초소형 전자 렌즈의 구동 특성을 조사·분석하였다. Einzel 렌즈의 retarding mode와 accelerating mode구동에서 포텐셜 분포는 유사하지만, electric field strength는 서로 다른 방향을 갖게 되어 서로 다른 형태의 전자 궤적을 보인다. 동일한 working distance에서 accelerating mode로 구동되는 전자렌즈는 retarding mode로 구동되는 경우보다 매우 높은focusing 전압을 필요로 한다. The analysis of operation characteristics of a miniaturized electrostatic electron lens system called an Einzel lens was performed using a simulation tool of FCM method. The potential distributions of Einzel lenses operated both in retarding and accelerating modes show similar features. But the electric fields determined from the potential distributions show opposite directions, which results in different features in the electron beam trajectory in each mode of operation. For the same working distance, focusing voltage in the accelerating mode is higher than that in the retarding mode.

The assembly of a fully functional microcolumn and its STEM mode operation

김호섭,D.W Kim,D.Y Kim,S.J Ahn,S.K Choi,S.S Park,Y.C Kim 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.43 No.51

A fully functional microcolumn composed of an electron emitter, micro-lenses, a double octupole de ector, and an Einzel lens was successfully assembled and operated in the STEM mode. We used a precise alignment method based on laser diraction through circular apertures instead of the conventional alignment method. This microcolumn was operated at a low energy of 300 eV. The scan range of the focused electron beam was around 80 m, and the beam current was measured to be 2 nA at the sample, which was 1.2 mm from the focusing lens. The results of the STEM-mode operation, both using the retarding and the accelerating mode, are reported. A fully functional microcolumn composed of an electron emitter, micro-lenses, a double octupole de ector, and an Einzel lens was successfully assembled and operated in the STEM mode. We used a precise alignment method based on laser diraction through circular apertures instead of the conventional alignment method. This microcolumn was operated at a low energy of 300 eV. The scan range of the focused electron beam was around 80 m, and the beam current was measured to be 2 nA at the sample, which was 1.2 mm from the focusing lens. The results of the STEM-mode operation, both using the retarding and the accelerating mode, are reported.

중소규모 사업장의 개인적 특성과 근골격계증상간의 상관관계 분석

김호섭,정명진,Kim, Ho-Seob,Jung, Myeong-Jin 국제문화기술진흥원 2021 The Journal of the Convergence on Culture Technolo Vol.7 No.3

We surveyed 27 workplaces and 1897 workers and analyzed the correlation between Personal characteristics of workers and Musculoskeletal Symptoms. The presence or absence of Symptoms of Musculoskeletal Disease in workers was based on The Management Target or higher in accordance with the guidelines for The Investigation of Harmful Factors in Musculoskeletal Burdened Work of the Korea Occupational Safety and Health Agency. Personal characteristics were divided into age, work load, housework burden, work experience, leisure type, gender, and marital status. In the survey, correlations were investigated through binominal logistic regression analysis for rank variables of work load, household burden, and work experience, and the significance of the results was confirmed by crosstabulation and chi-square analysis for other nominal variables. And in the case of other variables, there was a slight trend, but it was confirmed that it was not statistically significant. As a result, We confirmed that the incidence rate of Musculoskeletal Disease Symptoms increased as the age of the workers was lower, the higher the workload and housework, if they were women, if they did not engage in leisure activities. However, considering that the results of this study are slightly different as a result of comparing the results of other studies, the data of this study can be used as rough indicators for the prevention of musculoskeletal disorders, but additional research is needed before using it as quantitative indicators. 27개 사업장, 1897 근로자를 대상으로 근골격계질환 증상조사표를 받아 근골격계증상과 근로자 개인적 특성과의 상관관계를 분석하였다. 근로자의 근골격계질환 증상 유무는 한국산업안전보건공단의 근골격계부담작업 유해요인조사 지침에 따라 관리대상자 이상을 기준으로 했으며 개인적 특성으로는 작업자의 연령, 업무부담, 가사부담, 직장경력, 여가종류, 성별, 결혼유무로 구분하였다. 조사는 업무부담, 가사부담, 직장경력의 서열변수는 이분형 로지스틱 회귀분석을 통해 상관관계를 조사하였으며 그 외 명목변수는 교차분석과 카이제곱분석으로 해당 결과의 유의성을 확인하였다. 그 결과 작업자의 연령이 낮을수록, 업무부하와 가사부담이 높을수록, 여성일 경우, 여가활동을 가지지 않을 경우 근골격계질환 증상발현율이 높아진다는 것을 확인하였다. 그러나 본 연구의 결과를 다른 연구결과와 비교한 결과 조금씩 결과가 다른 점을 미루어볼 때 본 연구의 자료를 근골격계질환 예방의 개략적인 지표로써 활용할 수는 있지만 정량적 지표로써 활용하가 전 추가적인 연구가 필요할 것으로 사료된다.

수심이 얕은 부영양 인공호(일감호)의 동 ${\cdot}$ 식물플랑크톤 동태학

김호섭,박제철,황순진,Kim, Ho-Sub,Park, Je-Chul,Hwang, Soon-Jin 한국하천호수학회 2003 생태와 환경 Vol.36 No.3

본 연구는 수심이 얕고 부영양화가 지속되고 있는 인공호수에서의 동 ${\cdot}$식물플랑크톤의 종 조성과 현존량의 계절변화, 수질인자와의 상관관계 그리고 PEG모델과의 비교를 위해 실시되었다. 식물플랑크톤의 분류군 별 계절적 출현양상은 봄과 가을에 녹조류와 규조류가 우점하고 여름에 남조류의 현존량이 증가함에 따라 PEG모델과 유사하였다. 그러나 현존량에 의한 우점종의 변화는 2002년 1월부터 3월가지 녹조류가 우점했던 것을 제외하고는 조사기간 내내 남조류가 우점 함으로써 PEG모델과 다르게 나타냈다. 수체 내 영양염의 증가가 나타난 봄철 녹조류가 증가하였고, 무기영양염의 감소와 함께 남조류의 우점비율이 증가하였다. 주요출현 남조류는 Microcystis, Oscillatoria, Lyngbya, Merismopedia속 내종들 이였고, 2000년 10월에 가장 높은 현존량을 나타났으며 (12.9${\pm}$5.8${\times}10^5$ cells/ml, 3.5${\pm}$0.9${\times}10^3{\mu}gC/l$), 엽록소 a ($r^2$ = 0.71, P< 0.001), TP농도 ($r^2$ = 0.62, P< 0.001)와 양의 상관관계를 나타냈다. 녹조류가 우점한 3월부터 5월 사이에 윤충류인 Keratella cochlearis와 같은 크기가 작은 윤충류의 증가가 나타났다. 성체보다는 대부분 유생의 비율이 (70%이상)높았던 요각류와 지각류 (Diaphanosoma brachyurum, Bosmina longirostris등)의 현존량 증가는 식물플랑크톤 중 와편모조류와 규조류가 증가한 6월과 9월 사이에 나타났다($r^2$=0.73, P< 0.001). 본 연구기간동안 동물플랑크톤 섭식에 의한 청수기는 관찰되지 않았으며, 동 ${\cdot}$ 식물플랑크톤의 다양성은 식물플랑크톤의 생물량 증가 시 회복되는 것으로 나타났다. 본 연구결과에서는 부영양 호수에서 동물플랑크톤의 섭식이나 제한영양염의 결핍이 식물플랑크톤의 현존량에 영향을 출 수 있으나 군집의 변화를 야기하지는 못함이 제시되었다. This study was attempted to understand seasonal dynamics of phyto- and zooplankton communities in shallow, eutrophic Lake llgam and to compare them with the PEG (Plankton Ecology Group) model. Seasonal succession pattern of phytoplankton community was similar to PEG model as Chlorophyceae and Baciliphyceae increase during spring and autumn fellowed by increase of Cyanophyceae. However, based on the cell density and biomass, a dominant phytoplankton community differed with PEG model: Cyanophyceae had been a dominant community throughout a year, except for ice-cover period during which Chlorophyceae was a dominant group. In spring, when ice melted and dissolved nutrients in water column increased, the increase of Chlorophyceae occurred: when nutrients (DIN and DIP) rapidly decreased, Cyanophyceae increase occurred. Microcystis, Oscillatoria, Lyngbya, Merismopedia were maior dominant species of Cyanophyceae and their cell density and/or biomass was the highest in October 2000 (12.9${\pm}$5.8${\times}10^5$ cells/ml, 3.5${\pm}$0.9${\times}10^3{\mu}gC/l$). Cyanophyceae biomass showed positive relationship with chlorophyll a ($r^2$ = 0.71,P< 0.001) and TP concentration ($r^2$ = 0.62, P< 0.001). Small-sized rotifers such as Keratella cochlearis, increased between March and May when Chlorophyceae increased. Both high standing crop of copepods and cladocerans, such as Diaphanosoma brachyrum and Bosmina longirostris occurred between June and September accompanied with the increase of Dinophyceae and Bacillariophyceae. There was no evidence that clear-water phase was caused by zooplankton grazing. The diversity and evenness index of phyto- and/or zooplankton increased with chlorophyll a concentration. These results suggest zooplankton grazing and limiting nutrient deficiency could lead to change of phytoplankton biomass, but not the phytoplankton community in Lake llgam.

SmBCO 초전도 선재 특성에 대한 Sm:Ba:Cu 조성비의 영향

김호섭,오상수,장세훈,민창훈,하홍수,하동우,고락길,염도준,문승현,정국채,Kim, H.S.,Oh, S.S.,Jang, S.H.,Min, C.H.,Ha, H.S.,Ha, D.W.,Ko, R.K.,Youm, D.J.,Moon, S.H.,Chung, K.C. 한국초전도학회 2011 Progress in superconductivity Vol.13 No.1

조성경사법을 이용하여 LMO/IBAD-MgO template 상에 EDDC 증착법을 이용하여 $Sm_{1+x}Ba_{2-x}Cu_{3+y}O_{7-d}$ 초전도 박막을 증착하였다. 테이프 형상의 기판상에 길이방향으로 $Sm_{1+x}Ba_{2-x}Cu_{3+y}O_{7-d}$ 박막의 조성비가 연속적으로 변하는 샘플을 얻을 수 있었고, 비접촉 Hallprobe를 이용하여 임계전류를 측정한 결과 조성비에 대응하는 연속적인 임계전류분포를 측정할 수 있었다. 본 조성비 영역 중 Sm:Ba:Cu = 1.01:1.99 :4.87의 조성비에서 최대의 임계전류를 보였다. 이 조성비에서 SmBCO 박막표면에 전체적으로 roof tile 형상의 결정립들이 관찰되었으며 국소적으로 2차상들이 관찰되었다. 조성 경사법을 이용하면 광범위한 조성비영역에서 신뢰도 높은 초전도특성, 결정배향성, 박막표면 형상 등을 조사할 수 있을 것으로 예상된다. The effects of Sm:Ba:Cu composition ratio in SmBCO coated conductor on their superconducting properties were investigated. The SmBCO coated conductors were fabricated by reactive co-evaporation method using EDDC(Evaporation using Drum in Dual Chamber) system. In this system, we could obtain various samples with different composition ratios in a batch by the technique providing composition gradient at deposition zone. From the specimens prepared by EDDC system, we found that composition ratio is uniform parallel to the drum axis, but gradient along the circumferential direction of the drum. We installed a shield having parallelogram open area between the deposition chamber and the evaporation chamber in EDDC system, and attached a 30 cm long template, which is parallel to drum axis, onto the drum surface. In this configuration, we could obtain SmBCO coated conductors having a gradient composition along the length of template. We measured the composition ratios and surface morphologies with periodic interval by SEM and EDAX, and confirmed the profile of composition ratio. We also measured critical current using non-contact Hall probe critical current measurement system and thereby could plot composition ratio vs. critical current. The maximum critical current was obtained, and the surface morphology with the shape of roof tile was observed at the corresponding composition ratio of Sm:Ba:Cu = 1.01:1.99:4.87. It was also found that composition ratio had an effect on not only critical current but also surface morphology.

오염물질 배출원과 하천에서의 유기탄소 분포 특성

김호섭,김상용,박지형,한미덕,Kim, Ho-Sub,Kim, Sang-Yong,Park, Jihyung,Han, Mideok 한국물환경학회 2017 한국물환경학회지 Vol.33 No.5

The fractionation characteristics of organic matter were investigated in inflow and effluent of each other pollution sources and river. While the DOC/TOC ratio in the influent of public sewage treatment plant and livestock disposal facilities was above 0.58, the POC/TOC ratio of human livestock Night soil treatment plant and stormwater runoff was more than 0.7. The TOC removal efficiency of public sewage treatment plant and human livestock Night soil treatment plant were 88.5 % and 99.6 %, respectively. Although the concentration distribution of organic matter pollution most of total organic carbon (TOC) in effluent of pollution sources accounted for dissolved organic carbon (DOC) type (DOC/TOC ratio >0.89) and Refractory-DOC (RDOC)/TOC ratio was higher (>0.65). The fractionation characteristics of organic matter in river were similar with that of sewage treatment plant and TOC concentration showed the positive correlation with DOC ($r^2=0.93$) and RDOC ($r^2=0.89$) concentration. The decay rate of Labile DOC (LDOC) (avg. $0.128day^{-1}$) was higher than labile particulate organic carbon (LPOC) ($0.082day^{-1}$), while that of DOC ($0.008day^{-1}$) was lower than POC ($0.039day^{-1}$) (paired t-test, p < 0.001, n = 5). These study results suggested that it should consider important both TOC and DOC as the target indicator to control refractory organic matter in pollution sources.

마이크로컬럼과 전계방출 전자 소스

김호섭,Kim, Ho-Seop 한국정보디스플레이학회 2020 인포메이션 디스플레이 Vol.21 No.5

Electron Beam Lithography

김호섭,Kim, Ho-Seop 한국광학회 2014 광학과 기술 Vol.18 No.3

IBAD-MgO 기판상에 플라즈마를 이용한 LaMnO₃ 저온 증착

김호섭,오상수,하동우,하홍수,고락길,문승현,Kim, H.S.,Oh, S.S.,Ha, D.W.,Ha, H.S.,Ko, R.K.,Moon, S.H. 한국초전도저온공학회 2012 한국초전도저온공학회논문지 Vol.14 No.1

LMO($LaMnO_3$) buffer layer of superconducting coated conductor was deposited on IBAD-MgO template in the plasma atmosphere at $650^{\circ}C$ which is relatively low compared with conventional deposition temperature of more than $800^{\circ}C$. Deposition method of LMO was DC sputtering, and target and deposition chamber were connected to the cathode and anode respectively. When DC voltage was applied between target and chamber, plasma was formed on the surface of target. The tape substrate was located with the distance of 10 cm between target and tape substrate. When anode bias was connected to the tape substrate, electrons were attracted from plasma in target surface to the tape substrate, and only tape substrate was heated by electron bombardment without heating any other zone. The effect of electron bombardment on the surface of substrate was investigated by increasing bias voltage to the substrate. We found out that the sample of electron bombardment had the effect of surface heating and had good texturing at low controlling temperature.

초전도 테이프 제작을 위한 니켈기판 상의 산화물 박막 증찰

김호섭,고락길,정준기,하홍수,송규정,박찬,Kim, Ho-Sup,Shi, Dongqui,Ko, Rock-Kil,Chung, Jun-Ki,Ha, Hong-Soo,Song, Kyu-Jeong,Park, Chan 한국전기전자재료학회 2004 전기전자재료학회논문지 Vol.17 No.12

High temperature superconducting coated conductor has a structure of <protecting layer>/<superconducting layer>/<buffer layer>/<metallic substrate>. The buffer layer consists of multi-layer, this study reports the deposition method and optimal deposition conditions of YSZ(Yttria-stabilized zirconia) layer which plays a important part in preventing the elements of substrate from diffusing into the superconducting layer. YSZ layer was deposited by DC reactive sputtering technique using water vapor for oxidizing deposited elements on substrate. To investigate optimal thickness of YSZ film, four YSZ/CeO$_2$/Ni samples with different YSZ thickness(130 nm, 260 nm, 390 nm, and 650 nm) were prepared. The SEM image showed that the surface of YSZ layer was getting to be rougher as YSZ layer was getting thicker and the growth mode of YSZ layer was columnar grain growth. After CeO$_2$ layer was deposited with the same thickness of 18.3 nm on each four samples, YBCO layer was deposited by PLD method with the thickness of 300 nm. The critical currents of four samples were 0, 6 A, 7.5 A, and 5 A respectively. This shows that as YSZ layer is getting thicker, YSZ layer plays a good role as a diffusion barrier but the surface of YSZ layer is getting rougher.