• Current Photovoltaic Research
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• v.9 no.3
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• pp.75-83
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• 2021

The tunnel oxide passivated contact (TOPCon) structure got more consideration for development of high performance solar cells by the introduction of a tunnel oxide layer between the substrate and poly-Si is best for attaining interface passivation. The quality of passivation of the tunnel oxide layer clearly depends on the bond of SiO in the tunnel oxide layer, which is affected by the subsequent annealing and the tunnel oxide layer was formed in the suboxide region (SiO, Si₂O, Si₂O₃) at the interface with the substrate. In the suboxide region, an oxygen-rich bond is formed as a result of subsequent annealing that also improves the quality of passivation. To control the surface morphology, annealing profile, and acceleration rate, an oxide tunnel junction structure with a passivation characteristic of 700 mV or more (V_oc) on a p-type wafer could achieved. The quality of passivation of samples subjected to RTP annealing at temperatures above 900℃ declined rapidly. To improve the quality of passivation of the tunnel oxide layer, the physical properties and thermal stability of the thin layer must be considered. TOPCon silicon solar cell has a boron diffused front emitter, a tunnel-SiO_x/n⁺-poly-Si/SiN_x:H structure at the rear side, and screen-printed electrodes on both sides. The saturation currents J_o of this structure on polished surface is 1.3 fA/cm² and for textured silicon surfaces is 3.7 fA/cm² before printing the silver contacts. After printing the Ag contacts, the J_o of this structure increases to 50.7 fA/cm² on textured silicon surfaces, which is still manageably less for metal contacts. This structure was applied to TOPCon solar cells, resulting in a median efficiency of 23.91%, and a highest efficiency of 24.58%, independently. The conversion efficiency of interdigitated back-contact solar cells has reached up to 26% by enhancing the optoelectrical properties for both-sides-contacted of the cells.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.19-25
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• 2002

Ternary $xSrO-yB_2O_3-0.1Al_2O_3$ and $xSrO-yB_2O_3-0.1SiO_2$ glasses were prepared as a function of R(${\equiv}x/y$). The fraction of four-coordinated brans ($N_4$), symmetric three-coordinated barons ($N_{3S}$), and asymmetric three-coordinated barons ($N_{3A}$) were determined quantitatively to study the structures of these glasses by $^{11}B$ NMR. The values of $Q_{cc}$ and ${\eta}$ for $BO_3$ unit in the glasses were 2.74MHz and 0.22, those for $BO_3{^-}$ unit were 2.54MHz and 0.55, and those for $BO_4$ unit 0.60~0.75MHz and 0.00, respectively. The structure of SrBAl glass at $R_{1st}$ consisted of tetraborate ($[B_8O_{13}]^{-2}$) units and 1st-modified diborate ($[B_2Al_2O_7]^{-2}$) units, and those for the glass at $R_{max}$consisted of diborate ($[B_4O_7]^{-2}$) units, metaborate ($[BO_2^{-1}]$), 1st-modified diborate units, and 2nd-modified diborate ($[B_2Al_2O_8]^{-4}$) units. Due to the oxygens introduced from the strontium oxide. $AlO_4$ units were preferably formed rather than $BO_4$ units. And, the structure of SrBSi glasses in the region $R{\leq}0.5$ could be viewed as binary $SrO-B_2O_3$ glasses structure diluted by silicate oxide: therefore, the Si atoms of the glasses did not contributed to the change the configuration around the boron atoms. The silicate oxide was formed the $SiO_4{^-}$ units rather than the $BO_3{^-}$ units by the oxygens introduced from the storntium oxide in the region of $R{\geq}R_{max}$, and structure of those glass at $R_{max}$ consisted of diborate units, metaborate units loose $BO_4([BO_2]^{-1})$, and $SiO_4{^-}([SiO_{2.5}]^{-1})$ units.

• The Journal of Engineering Geology
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• v.19 no.2
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• pp.235-250
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• 2009

Environmental elements such as B, Br, and Sr in groundwater from Bukahn-myeon, Yeongcheon, Gyeongbuk Province, were investigated in order to know their origin with emphasis on hydrochemistry. pH ranges from 7.37 to 8.39. B content is 0.41${\sim}$4.62 mg/L with an average 1.74 mg/L and Br content is 0${\sim}$3.24 mg/L with an average 2.22 mg/L, and Sr content is 0.93${\sim}$8.64 mg/L with an average 2.76 mg/L. The water types plotted by the Piper diagram are different but mostly $Ca-HCO_3$. Some constituents contributing to EC are Na, $SO_4$, Cl with high determinative coefficients($R^2$) of 0.85, 0.70, 0.90, respectively. The coefficients($R^2$) of Cl to Na, K, $SO_4$ are 0.54, 0.68, 0.53, respectively. It should be noted that there are high cocfficients($R^2$) of B-Sr and $Sr-SO_4$ with 0.65, 0.64, respectively. The Cl/Br ratios are 5.21${\sim}$30.70 due to significant depletion of Cl. The $SO_4/Cl$ ratios are 1.32${\sim}$27.24 with an average of 5.92, ascribed to abundant introduction of $SO_4$ or significant depletion of Cl. Chemical speciation calculated shows that B exists mostly as $H_3BO_3$ with less $H_2BO^-_3$ and Br exists as only $Br^-$. Sr exists mostly as $Sr^2$ with less $SO_4$. Saturation index represents that goundwater is supersaturated with respect to barite, kaolinite, illite, K-mica, and smectite while it is slightly undersaturated with respect to silica, gypsum, anhydrite, talc, chrysotile, feldspar, kaolinite, illite, K-mica, and smectite. The saturation index of celestine is -2.23${\sim}$-0.13 indicating more Sr can be incorporated into groundwater. Groundwater is still much undersaturated to halite. It is likely that the origin of S and Sr was related to the Yucheon volcanic rocks. Br might be originated from the local geological features with introduction of anthropogenic matters.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.3
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• pp.135-152
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• 1975

The following informations are known from physical and chemical characteristics of orchard soils and nutritional diagnosis of orange leaves in Jeju. 1. Most orange orchards are located on terrace and cindercone thus soil moisture and microclimate of an orchard will greatly be affected by its topography. 2. Excessive well drainage, shallow soil depth, high content of gravels, low solid phase ratio and strong wind will give severe problem of soil moisture and wind errosion, thus the exte- nsion of soil depth is necessary for maintain nutrients, water and sufficient root volume. 3. Available soil water was significantly and positively correlated with organic matter content and clay content also contributes to available soil water. Vinyl mulching was greatly helpful for soil water conservation, wind errosion prevention, soil temperature increases during winter. 4. Abundant amphoteric amorphous allophane take a key role to fix phosphorus and also rations and thus it is the major factor to determine fertilizer efficiency. Lime and phosphorus must be applied in deeper soil layer. Release of filed phosphorus must be reevluated for availability. 5. Organic matter such as see weeds will greatly increase fertilizer efficiency and low fertilizer efficiency during spring may be related to available soil water. 6. Nitrogen was in superoptimum and Mg was enough but P and Ca were somewhat deficient according to leaf analysies while K was deficient according to fruit analysis. Phosphorus application increased sugar/acid ratio and potassium decreases rind percentage. 7. Manganese deficiency and toxicity appeared in a few places. Iron and boron were enough. Most places showed tendency of copper excess but some places showed copper deficiency. 8. Soiling after elimination of rock base, application of slow release fertilizer and abundant organic matter, vinyl mulching and drip irrigation will increase fertilizer efficiency greatly and fruit yield drastically.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.368-370
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• 2013

투명 전극은 전기전도도를 갖는 동시에 가시광선을 투과하는 소재를 말하며, 구체적으로는 빛의 파장이 400~700 nm 영역대의 가시광선을 80% 이상 투과하며 전기전도도가 비저항으로 $10^{-3}{\Omega}cm$이하이거나 면저항이 $10^3{\Omega}$/${\Box}$소재를 의미한다. 투명 전극은 전기전도도에 따라 사용되는 용도가 다양하다. LCD, PDP, OLED 와 같은 평판디스플레이 및 3D 디스플레이의 투명전극으로 사용되는 핵심재료일 뿐만 아니라 터치스크린, 투명필름, 대전방지막, 열반사막, EMI 방지막, 태양전지 분야에 광범위하게 이용되고 있다. 일반적으로, 투명전극 박막에 가장 많이 사용되고 있는 소재는 ITO (indium tin oxide)이나, 주성분인 In의 사용량 증가로 상용 ITO 타겟 가격이 급등하고 있음으며, 고가의 ITO 타겟을 대체하기 위한 저가의 투명전극 소재 개발이 절대적으로 요구되며, 신규 소재 개발을 통한 기술력 우위 선점이 필수적으로 요구되는 상황이다. 본 연구에서는 기존에 디스플레이 분야에서 널리 활용되는 고가의 ITO를 대체하기 위한 다성분 금속산화물 투명전극 스퍼터링 타겟 제조기술을 개발하기 위한 연구로서, Metal이 첨가된 In-Ga-Zn-O기반의 3성분계 투명도전성 소재를 조성설계, 고밀도 균질 타겟 제조 및 투명전극 박막을 형성하는 연구를 실시하였다. 고체산화물 산화인듐(In2O3)분말, 산화갈륨(Ga2O3) 분말그리고 산화아연(ZnO)분말과 Metal을 몰비로 칭량한 후 분말을 폴리에틸렌제 포트에 넣고 에탄올을 충분히 채운 후 지르코니아(ZrO2) 볼(ball)을 이용하여 24 h 동안 볼 밀링(ball milling) 방법으로 혼합한 뒤, $120^{\circ}C$의 플레이트위에서 마그네틱 바로 stirring하면서 건조하였다. 이 분말을 건조기에서 완전히 건조한 후 알루미나 유발을 이용해서 pulverizing한 후 sieving기를 이용하여 분말의 조립화를 하였다. 이 분말을 금형에 넣고 300 kg/$cm^2$의 압력으로 press하여 성형한 뒤 대기중에서 소결하였다 소결을 위한 승온 온도는 $10^{\circ}C$/min이었고 소결은 $1,450^{\circ}C$에서 6 h 동안 하였다. IGZO target의 조성 비율은 1:1:12 (mol%)를 사용하였으며, 첨가한 Metal은 Boron (B), Germanium (Ge), Barium (Ba)을 사용하여 타겟을 제작하였다. M-IGZO 박막은RF magnetron Sputter를 이용하여 증착하였으며, 앞선 실험에서 제작한 타겟을 사용하여 M-IGZO박막을 투명전극으로 사용하기 위한 각각의 특성을 파악하였다. 모든 박막은 상온에서 증착을 하였으며, 증착된 박막두께를 측정하기 위해 ${\alpha}$-step IQ를 사용하였고, 광학적 특성을 분석하기 위해 UV-Visible spectrophotometer 로 투과율을 측정하였다. 그리고 전기적 특성을 측정하기 위해 Hall effect measurement 및 4-probe를 사용하였으며, 결정성 분석을 위하여 XRD를 이용하여 분석하였다. 표1은 M-IGZO타겟을 사용하여 증착시간에 따른 면저항 특성을 나타내었다. Ge, B, Ba이 첨가된 IGZO 박막은 증착시간이 증가할수록 면저항이 낮아짐을 알 수 있었다. 또한, Ge이 첨가된 IGZO 박막이 다른 금속이 첨가된 IGZO 박막의 면저항보다 현저히 낮음을 알 수 있었다. Fig. 1(a), (b), (c)는 각 타겟을 동일한 조건으로 증착을 하여 광학적특성을 나타내는 그래프이다. GZO 박막의 광학적 특성을 보면 가시광 영역에서 평균 투과율은 모두 80% 이상으로 우수한 광투과 특성을 보여 투명전자소자로 사용가능하다. 특히, 자외선 영역을 모두 차단하는 UV cut 능력이 우수함을 알 수 있었다. 따라서, 금속이 첨가된 IGZO 박막을 태양전지용 투명전극으로 사용할 경우, 자외선에 의하여 수명이 단축되는 현상을 줄여줄 수 있음을 기대할 수 있으며 내구성 향상에 크게 기여할 것으로 보인다. Fig. 2는 Ge=0, 0.5, 5%인 IGZO 투명전극을 총 40회 반복하여 증착을 실시한 후 각각의 면저항을 측정한 결과이다. 실험결과에 따르면 Ge가 0%, 5%인 IGZO 투명전극은 증착을 거듭할수록 면저항이 증가하는 결과를 나타내었으며, 0.5%인 IGZO 투명전극은 점차 안정화되어가는 결과를 나타내었다. 따라서 안정화 되었을 때 평균 면저항은 26ohm/sq.로 나타났으며, 광투과율은 Fig. 3과 같이 가시광영역에서 평균 80%이상의 결과를 보였으며, 550 nm에서는 86.36%의 우수한 특성을 나타내었다. 본 연구에서는 Metal이 첨가된 In-Ga-Zn-O기반의 3성분계 투명도전성 소재 target을 제작하여 RF magnetron sputter로 박막을 형성한 후 특성을 비교하였다. M-IGZO target 중 Ge (0.5%)을 첨가한 IGZO 타겟을 사용한 투명전극이 가장 우수한 특성을 보였으며, 제작된 M-target의 In 비율이 30% 정도로 기존의 ITO (90%) 대비하여 투명전극 제작 단가를 절감할 수 있다.

• Journal of The Korean Society of Grassland and Forage Science
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• v.8 no.2
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• pp.92-98
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• 1988

With a purpose of finding out the effects of magnesium and boron enriched organic-compound fertilizer application on the dry matter yield, yield components and changes in the botanical composition on the hilly pasture, a field experiment was arranged with five different treatments as a randomized block desigh and lasted from September, 1984 to the end of growing season in 1986. The results obtained are summarized as follows: 1. As a early plant growth and development, winter hardiness, growth vigour and coverate of grasses at the plots with organic-compound fertilizer application were better comparing to single dressing. 2. Average dry matter yields for two years were shown significantly high due to increasing amount of fertilizer. This trend was same both single and organic-compound fertilizer. And dry matter yields with organic-compound fertilizer application of low (8,693.1 kg/ha) and conventional level (12,758.7 kg/ha) were appeared to increase by 10 and 15% than those of single dressing of Low (7,930.6 kg/ha) and conventional level (11,122.6 kg/ha), respectively. But it was not significant difference. 3. Dry matter yield of grasses was significantly gained by increasing amount of fertilizer. The yield of legumes at the plots with organic-compound fertilizer application the yields of grasses were a litle more increased by 8-14%, and legumes were much more gained by 26-29% than those of the same species groups with single dressing, but it was not significant between the differnet kinds of fertilizer in the same fertilizing level. 4. At the grassland management, the rate of legumes tended to dominate at the plot without fertilization gradually. On the other hand, the botanical compositions and the rates of grasses were much better maintained at the plots with fertilization. But the rates of legumes with organic-compound fertilizer application tended to increase a little more than those of single dressing gradually. 5. All of the soil chemical properties after the experiment were much more improved comparing to before the experiment. But the average contents of soil organic matter and available $P_2O_5$ were slightly higher at the plot with organic-compound fertilization, on the other hand, pH and exchangeable cations tended to a little less than those of single dressing.

• Resources Recycling
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• v.18 no.5
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• pp.52-62
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• 2009

This research was carried out to formulate environmentally friendly wood preservatives with okara and to investigate the effects of the acid concentration used for the hydrolysis of okara and salt type on the decay resistance of the preservatives. Okara-based preservatives were formulated with okara hydrolyzates, which were prepared with 0, 1%, and 2% sulfuric acid at $25^{\circ}C$ for 1 hr, and salts such as copper chloride and/or sodium borate. The preservatives were treated into wood blocks by vacuum-pressure method, and then the treated wood blocks were leached in $70^{\circ}C$ hot water for 72 hrs. The fungal treatments of the leached wood blocks were conducted by brown-rot fungus, Tyromyces palustris, and white-rot fungus, Trametes versicolor, to examine the decay resistance of the preservatives. As the acid concentration used for hydrolysis of okara increased, the treat-ability and decay resistance of the preservatives were improved, which the leachability was decreased. Wood blocks treated with the okara/copper or okara/copper/borax, showed very good decay resistance against T. palustris and T. versicolor. However, wood blocks treated with the okara/borax and okara-free preservative solutions, were observed the fungal decay by T. palustris. The optimal conditions for the preparation of okara-based wood preservatives were formulated with okara hydrolyzed with 1% sulfuric acid, copper chloride and borax.

• Horticultural Science & Technology
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• v.30 no.5
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• pp.477-483
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• 2012

This study was carried out to investigate the influence of copper concentrations in fertilizer solution on the growth of and nutrient uptake by domestically bred strawberries. The characterization of toxicity symptoms as well as tissue analyses based on dry weight of above ground tissue were also conducted to determine the threshold levels in plants when toxicity developed in copper. The dry weights of the above ground tissue were not significantly different among the treatments of 0.25 mM to 1.0 mM in 'Keumhyang' and 'Maehyang' strawberries and that of 0.25 mM to 3.0 mM in 'Seolhyang' strawberry. This indicates that the 'Seolhyang' strawberry is more tolerant to copper toxicity than 'Keumhyang' or 'Maehyang' strawberries. Application of copper at high concentrations resulted in severe toxicity such as death of extensive areas of leaves. The lower leaves became yellow and die rapidly as the symptoms spread up the plants. The leaf blades and petioles died back to the crown and hang on by mechanical attachment. Symptoms of copper toxicity in lower leaves developed as browning on leaf margins and in patches between leaf veins that became necrotic. The elevation of copper concentrations in fertilizer solution did not influence the tissue phosphorus, potassium, calcium, and magnesium contents based on the dry weight of the above ground tissue. The tissue copper contents increased lineally as the copper concentrations in fertilizer solution were elevated. But the tissue iron, manganese and boron contents were not influenced by the concentrations. When the concentration of copper at which growth of a plant is retarded by 10% is regarded as threshold level, the copper contents based on dry weight of above ground plant tissue should be lower than 71.4, 57.9 and 74.8 $mg{\cdot}kg^{-1}$ in 'Keumhyang', 'Maehyang' and 'Seolhyang' strawberries, respectively. The symptom characterization and established threshold level in copper toxicity would help growers to prevent the reduction of crop growth and yield in 'Seolhyang' strawberry cultivation.

• Progress in Medical Physics
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• v.18 no.2
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• pp.87-92
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• 2007

A thermal neutron beam facility utilizing a typical tangential beam port for Neutron Capture Therapy was installed at the HANARO, 30 MW multi-purpose research reactor. Mixed beams with different physical characteristics and relative biological effectiveness would be emitted from the BNCT irradiation facility, so a quantitative analysis of each component of the mixed beams should be performed to determine the accurate delivered dose. Thus, various techniques were applied including the use of activation foils, TLDs and ionization chambers. All the dose measurements were perform ed with the water phantom filled with distilled water. The results of the measurement were compared with MCNP4B calculation. The thermal neutron fluxes were $1.02E9n/cm^2{\cdot}s\;and\;6.07E8n/cm^2{\cdot}s$ at 10 and 20 mm depth respectively, and the fast neutron dose rate was insignificant as 0.11 Gy/hr at 10 mm depth in water The gamma-ray dose rate was 5.10 Gy/hr at 20 mm depth in water Good agreement within 5%, has been obtained between the measured dose and the calculated dose using MCNP for neutron and gamma component and discrepancy with 14% for fast neutron flux Considering the difficulty of neutron detection, the current study support the reliability of these results and confirmed the suitability of the thermal neutron beam as a dosimetric data for BNCT clinical trials.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.3
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• pp.332-340
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• 2014

The purpose of this study was to establish the optimal growth temperature and to select genetic resources for production of cowpea sprouts. Seowon was treated between $15^{\circ}C$ and $30^{\circ}C$ at intervals of $3^{\circ}C$ to investigate growth temperature. Twelve resources, including Seowon, IT154149, IT154153, Tvu7426, and Tvu7778, were used for cultivating sprouts at a temperature of $27^{\circ}C$. The yield ratio of cowpea sprouts was highest at $27^{\circ}C$ (657%), and was reduced when growth temperature was decreased. The hard seed rate was lower when the growth temperature was increased. Vitamin C content was highest at $24^{\circ}C$ (2.85 mg/g), ranged between 2.15 and 2.29 mg/g at other growth temperatures, and increased with the length of the growth period. The inorganic component content of cowpea sprouts did not vary based on growth temperature, while the amino acid content increased with increasing growth temperature between $15^{\circ}C$ and $24^{\circ}C$, and then subsequently decreased as growth temperature rose from $24^{\circ}C$ to $30^{\circ}C$. IT154153 had the highest yield ratio of cowpea sprouts per genetic resource (647%), followed by Seowon (615%), and Tvu7426 (608%). Genetic resources with a higher yield ratio had smaller seeds, a thinner seed coat, and superior germinability. The inorganic components found at highest concentrations in the cowpea sprouts were potassium, magnesium, calcium, sodium, iron, molybdenum, and zinc (in that order). In comparison to raw seeds, the protein, calcium, zinc, molybdenum, and iron content in the cowpea sprouts was higher, while the content of aluminum and boron was lower.