환축추 골강직과 류마티스 관절염양 수부변형을 동반한 연소형 강직성 척추염

장효식 ( Hyo Shick Chang ),신기철 ( Ki Chul Sin ),김재덕 ( Jae Duk Kim ),박영아 ( Young Ah Park ),기명주 ( Myung Ju Ki ),장현규 ( Hyun Kyu Chang ),이지영 ( Jee Young Lee ) 대한류마티스학회 2003 대한류마티스학회지 Vol.10 No.2

Ankylosing spondylitis (AS) is a heterogeneous and systemic rheumatic disorder of unknown cause that is characterized by inflammation of the spine and sacroiliac joints. It is more common in young men. The disease is frequently associated with peripheral arthritis, enthesitis, anterior uveitis and high prevalence of HLA-B27. In some patients with AS, peripheral arthritis can occurs earlier than spinal symptom and more commonly affects the lower extremities than the upper extremities. Unlike men, women appear to have milder or atypical AS, especially at juvenile onset. However, involvement of the hands is extremely rare. Juvenile AS, defined as onset of disease prior to the age of 16 years, is considered a pediatric form of AS. On the other hand, although the atlantoaxial subluxation has been infrequently observed in patients with ankylosing spondylitis, atlantoaxial bony ankylosis has not been described in the literature. We describe a 23-year-old woman with juvenile AS who developed the atlantoaxial bony ankylosis and the hand involvement mimicking rheumatoid arthritis. Besides the rheumatoid-like hands and atlantoaxial bony ankylosis, she has shown the typical features of spondyloarthrpathy such as bilateral sacroiliitis, inflammatory spinal pain, enthesitis, severe arthritis of both hip joints, and positive HLA-B27 test.

한국 중부 지역의 태양광 모듈 타입에 따른 발전량 특성

장효식(Chang Hyo Sik) 한국태양에너지학회 2018 한국태양에너지학회 논문집 Vol.38 No.1

Solar panels are modules made up of many cells, like the N-type monosilicon, P-type monosilicon, P-type multisilicon, amorphous thin-film silicon, and CIGS solar cells. An efficient photovoltaic (PV) power is important to use to determine what kind of cell types are used because residential solar systems receive attention. In this study, we used 3-type solar panels - such as N-type monosilicon, P-type monosilicon, and CIGS solar cells - to investigate what kind of solar panel on a house or building performs the best. PV systems were composed of 3-type solar panels on the roof with each ~1.8 kW nominal power. N-type monosilicon solar panel resulted in the best power generation when monitored. Capacity Utilization Factor (CUF) and Performance Ratio (PR) of the N-type Si solar panel were 14.6% and 75% respectively. In comparison, N-type monosilicon and CIGS solar panels showed higher performance in power generation than P-type monosilicon solar power with increasing solar irradiance.

MoOx를 적용한 전하선택접합의 이종접합 실리콘 태양전지 적용 연구

장효식(Hyo sik Chang),정민지(Minji Jeong) 한국태양에너지학회 2019 한국태양에너지학회 학술대회논문집 Vol.2019 No.10

The Bandgap Change of TiO₂ as the Thickness and Annealing Condition Change

Youngjoon Cho(조영준),Hyosik Chang(장효식) 한국태양에너지학회 2020 한국태양에너지학회 학술대회논문집 Vol.2020 No.10

고효율 실리콘 태양전지를 위한 lotus surface 구조의 형성

정현철,백용균,김효한,음정현,최균,김형태,장효식,Jung, Hyun-Chul,Paek, Yeong-Kyeun,Kim, Hyo-Han,Eum, Jung-Hyun,Choi, Kyoon,Kim, Hyung-Tae,Chang, Hyo-Sik 한국결정성장학회 2010 韓國結晶成長學會誌 Vol.20 No.1

단결정 실리콘 태양전지의 광학적 손실을 감소시키는 표면 텍스쳐링은 최종 셀의 효율을 향상시키기 위하여 매우 중요하다. 본 연구에서는 2-step texturing의 공정으로 기존의 텍스쳐링에서 이루어진 피라미드에 수 많은 sub-micrometer 사이즈의 구조를 형성시켰다. $AgNO_3$ 용액으로 웨이퍼 표면에 Ag코팅을 한 후, 그 웨이퍼를 다시 HF/$H_2O_2$ 용액으로 수십초 동안 식각을 거치게 된다. 결과적으로, 피라미드 위에 생성된 수 nm사이즈의 구조물들은 $AgNO_3$의 농도 및 식각 시간의 변화에 의해 그 크기와 굵기가 변화하는 것을 알 수 있었다. 웨이퍼의 표면이 2-step texturing에 의해 식각이 이루어지면 연잎의 거친 표면과 비슷해지고, 그 결과 평균 10% 이상의 반사율을 보이던 기존 웨이퍼에서 3% 이하의 낮은 반사율을 얻을 수 있었다. 이는 일반적인 텍스쳐링과 anti-reflection coating을 거친 웨이퍼의 반사율보다 낮은 결과이다. The reduction of optical losses in mono-crystalline silicon solar cell by surface texturing is a critical step to improve the overall cell efficiency. In this study, we have changed the sub-micrometer structure on the micrometer pyramidal structure by 2-step texturing. The Ag particles were coated on the micrometer pyramid surface in $AgNO_3$ solution, and then the etching with hydrogen fluoride and hydrogen peroxide created even smaller nano-pyramids in these pyramids. As a result, we observed that the changes of size and thickness of nano structure on pyramidal surface were determined by $AgNO_3$ concentration and etching time. Using 2-step texturing, the surface of wafers is etched to resemble the rough surface of a lotus leaf. Lotus surface can reduce average reflectance from 10% to below 3%. This reflectance is less than conventional textured wafer including anti-reflection coating.

N형 양면 수광 태양전지를 위한 레이저 공정의 후면 패시베이션 적층 구조 영향성

김기륜,장효식,Kim, Kiryun,Chang, Hyo Sik 한국재료학회 2020 한국재료학회지 Vol.30 No.5

In this paper, we investigated the effect of the passivation stack with Al₂O₃, hydrogenated silicon nitride (SiN_x:H) stack and Al₂O₃, silicon oxynitride (SiON_x) stack in the n type bifacial solar cell on monocrystalline silicon. SiNx:H and SiON_x films were deposited by plasma enhanced chemical vapor deposition on the Al₂O₃ thin film deposited by thermal atomic layer deposition. We focus on passivation properties of the two stack structure after laser ablation process in order to improve bifaciality of the cell. Our results showed SiN_x:H with Al₂O₃ stack is 10 mV higher in implied open circuit voltage and 60 ㎲ higher in minority carrier lifetime than SiON_x with Al₂O₃ stack at Ni silicide formation temperature for 1.8% open area ratio. This can be explained by hydrogen passivation at the Al₂O₃/Si interface and Al₂O₃ layer of laser damaged area during annealing.

실리콘 전하선택접합 태양전지 적용을 위한 원자층 증착법으로 증착된 VO_x 박막의 특성

박지혜,장효식,Park, Jihye,Chang, Hyo Sik 한국재료학회 2020 한국재료학회지 Vol.30 No.12

Silicon heterojunction solar cells can achieve high conversion efficiency with a simple structure. In this study, we investigate the passivation characteristics of VOx thin films as a hole-selective contact layer using ALD (atomic layer deposition). Passivation characteristics improve with iVoc (implied open-circuit voltage) of 662 mV and minority carrier lifetime of 73.9 µs after post-deposition annealing (PDA) at 100 ℃. The improved values are mainly attributed to a decrease in carbon during the VOx thin film process after PDA. However, once it is annealed at temperatures above 250 ℃ the properties are rapidly degraded. X-ray photoelectron spectroscopy is used to analyze the chemical states of the VOx thin film. As the annealing temperature increases, it shows more formation of SiOx at the interface increases. The ratio of V5+ to V4+, which is the oxidation states of vanadium oxide thin films, are 6:4 for both as-deposition and annealing at 100 ℃, and 5:5 for annealing at 300 ℃. The lower the carbon content of the ALD VOx film and the higher the V5+ ratio, the better the passivation characteristics.

산처리와 일방향 응고를 이용한 실리콘 정제

음정현,장효식,김형태,최균,Eum, Jung-Hyun,Chang, Hyo-Sik,Kim, Hyung-Tae,Choi, Kyoon 한국결정성장학회 2008 한국결정성장학회지 Vol.18 No.6

최근 실리콘 원료의 부족에 따른 가격상승으로 인하여 99.9999% 이상의 순도를 지닌 폴리 실리콘을 더 저렴하게 제조하기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 순도 99%의 금속급 실리콘(MG-Si)을 원료로 산처리와 일방향 응고를 통해 고순도로 정제하는 연구를 수행하였다. MG-Si 럼프를 플레너터리 밀로 분쇄한 후 HCl/$HNO_3$/HF 산 수용액에서 처리하였다. 그 결과 Al, Fe, Ca, Mn 등과 같은 금속 불순물들의 실리콘 내 함량이 크게 감소하면서 실리콘의 순도는 99.995%까지 향상되었다. 정제된 실리콘 분말을 성형한 후 HEM로를 이용하여 용융시킨 뒤, 일방향 응고를 통하여 잉곳을 제조하였다. 성장시킨 다결정 실리콘 잉곳은 $0.3{\Omega}{\cdot}cm$의 비저항과 $3.8{\mu}{\cdot}sec$의 열 운반자 소멸시간(minority carrier life time)을 나타내었다. Recently the shortage of silicon resources especially for poly-silicon of purity higher than 99.9999% leads to search for the more cheap and quick synthesizing routes for silicon feedstock. In order to solve this situation, we investigated the purification process of metallurgical grade (MG) silicon of purity around 99% by the acid leaching and following the unidirectional solidification. MG-Si lumps are pulverized with a planetary mill, and then leached with HCl/$HNO_3$/HF acid solution. As a result, the concentration of metal impurities including Al, Fe, Ca, Mn, etc. decreased dramatically. This process led to silicon content higher than 99.99%. The purified silicon powders were compacted and have been melted and uni-directionally solidified with heat exchange method (HEM) furnace. The properties of multicrystalline silicon ingots were specific resistance of $0.3{\Omega}{\cdot}cm$ and minority carrier life time (MCLT) of $3.8{\mu}{\cdot}sec$.

결정질 실리콘 태양전지의 패시베이션 적용을 위한 Al₂O₃/SiON 적층구조의 열적 안정성에 대한 연구

조국현,장효식,Cho, Kuk-Hyun,Chang, Hyo Sik 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.3

We investigated the influence of blistering on $Al_2O_3$/SiON stacks and $Al_2O_3$/SiNx:H stacks passivation layers. $Al_2O_3$ film provides outstanding Si surface passivation quality. $Al_2O_3$ film as the rear passivation layer of a p-type Si solar cell is usually stacked with a capping layer, such as $SiO_2$, SiNx, and SiON films. These capping layers protect the thin $Al_2O_3$ layer from an Al electrode during the annealing process. We compared $Al_2O_3$/SiON stacks and $Al_2O_3$/SiNx:H stacks through surface morphology and minority carrier lifetime after annealing processes at $450^{\circ}C$ and $850^{\circ}C$. As a result, the $Al_2O_3$/SiON stacks were observed to produce less blister phenomenon than $Al_2O_3$/SiNx:H stacks. This can be explained by the differences in the H species content. In the process of depositing SiNx film, the rich H species in $NH_3$ source are diffused to the $Al_2O_3$ film. On the other hand, less hydrogen diffusion occurs in SiON film as it contains less H species than SiNx film. This blister phenomenon leads to an increase insurface defect density. Consequently, the $Al_2O_3$/SiON stacks had a higher minority carrier lifetime than the $Al_2O_3$/SiNx:H stacks.

다양한 조건의 플라즈마 원자층 증착법으로 증착된 Mo 금속의 전기적 특성

임태완,장효식,Lim, Taewaen,Chang, Hyo Sik 한국재료학회 2019 한국재료학회지 Vol.29 No.11

Molybdenum is a low-resistivity transition metal that can be applied to silicon devices using Si-metal electrode structures and thin film solar cell electrodes. We investigate the deposition of metal Mo thin film by plasma-enhanced atomic layer deposition (PE-ALD). $Mo(CO)_6$ and $H_2$ plasma are used as precursor. $H_2$ plasma is induced between ALD cycles for reduction of $Mo(CO)_6$ and Mo film is deposited on Si substrate at $300^{\circ}C$. Through variation of PE-ALD conditions such as precursor pulse time, plasma pulse time and plasma power, we find that these conditions result in low resistivity. The resistivity is affected by Mo pulse time. We can find the reason through analyzing XPS data according to Mo pulse time. The thickness uniformity is affected by plasma power. The lowest resistivity is $176{\mu}{\Omega}{\cdot}cm$ at $Mo(CO)_6$ pulse time 3s. The thickness uniformity of metal Mo thin film deposited by PE-ALD shows a value of less than 3% below the plasma power of 200 W.