• Journal of the Korean Wood Science and Technology
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• 제15권3호
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• pp.56-67
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• 1987

Plywoods used for construction as a decorative interior material are inflammable and can make fire accidents, causing destruction of human life and property. Therefore, it is indeed required to make fire-retardant treated plywood. In this study, 3.7mm yellow meranti plywoods were soaked in 18% boric acid solutions and tap water by hot-cold bath for 1/2, 2/2, 4/2, 6/2 hours and redrying of treated plywoods was carried out by press drying at the platen temperature of 110, 130, 160, $180^{\circ}C$ and then it was conducted to investigate solution absorption, drying rates, dynamic young's modulus. specific gravity and fire-retardant factors such as burning point, flame spread length. flame exhausted time, back side carbonized area and weight loss by treating time, treating solutions and platen temperature. The results are as follows; 1. When plywood was impregnated with the hot bath temperature of $70^{\circ}C$ for 1. 2, 4, 6 hours and the cold bath temperature of $15^{\circ}C$ for 2 hours respectively, retentions of boric acid were 1.565, l.597, 1.643, 1.709kg/$(30cm)^3$ and all of them exceeded the minimum retention [1.125kg/$(30cm)^3$] even in the shortest treatment. 2. In hot-cold bath method for 1/2 hours, the drying rates of treated plywood remarkably increased with the extension of platen temperature of 110, 130, 160, $180^{\circ}C$ and the values of boric acid treated plywood were 5.900, 10.196, 45.42, 54.958m.c%/min and the values of water treated plywood were 6.014, 12.373, 46.520, 55.730m.c%/min and drying rates of water treated plywood were faster than those of boric acid treated plywood. 3. The values of boric acid treated plywoods in dynamic young's modulus were widely higher than those of water treated plywoods. And it can be observed that there were highly significant differences for treating time between dynamic young's modulus, and the values of boric acid plywoods increased with the extension of treating time but on the contrary water treated plywoods were decreased values with prolonged time 4. It was observed that there were highly significant differences for platen temperature between dynamic young's modulus. When the values of water treated plywoods in dyna nic young's modulus were abruptly decreased according to the rise of platen temperature. boric acid treated plywoods showed rather increased values at $160^{\circ}C$ of platen temperature. And in 2- way interactions, there were also highly significant for dynamic young's modulus between treating time x treating solutions and platen temperature x treating solutions. 5. Correlation coefficients of fire-retardant factors were shown in table 5. It could be recognized that there were close correlations between the treating solutions and burning point, flame spread length, back side carbonized area, flame exhausted time and weight loss, but there was no correlation between fire-retardant factors and treating time and platen temperature. 6. From table 6, it can be observed that there were highly significant differences for burning point, flame spread length, flame exhausted time, back side carbonized area, weight loss between treating solutions. And in 2-way interactions, there were highly significant for burning point, flame spread length, weight loss between treating time $\times$ treating solutions.

• 한국지하수토양환경학회지:지하수토양환경
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• 제9권4호
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• pp.8-14
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• 2004

카드뮴과 크롬으로 오염된 토양에 EDTA 와 붕산 혼합용출제를 주입하는 토양수세법(Soil flushing)을 적용 시 최적운전조건을 결정하기 위해서 여러 가지 반응조건에서 카드뮴과 크롬의 제거효율을 측정하였다. 카드뮴의 제거효율은 EDTA 농도가 0.001M에서 0.1M로 증가하면서 $73.2\%$에서 $98.5\%$로 $25.3\%$증가하였으며, 크롬의 제거효율은 붕산의 농도가 0.001M에서 0.1M로 증가하면서 $59.2\%$에서 $100\%$로 $40.8\%$가 증가하였다. 서로 다른 특성을 갖고 있는 카드뮴과 크롬 오염토양에 pH가 3,5,7로 조정된 0.005M EDTA 와 0.005M 붕산 혼합용출제를 주입하여 제거효율을 측정한 결과 카드뮴의 제거효율은 pH가 3에서 7로 증가함에 따라 $92.4\%$에서 $80.9\%$로 감소하였으며, 크롬의 제거효율은 pH 5에서 $70.4\%$로 가장 높았다. pH 5에서 EDTA&붕산 혼합용출제의 농도비를 변화시키면서 카드뮴의 제거효율을 측정한 결과 [EDTA]:[붕산]=0.01M:0.1M에서 가장 효율적이며, 크롬의 제거효율은 [붕산] 주입농도가 0.1M이상일 때 가장 효율적인 것으로 조사되었다. 광산지역과 산업지역에서 채취한 실제오염토양에 적용한 실험에서도 비슷한 결과를 얻었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.371-372
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• 2009

• Corrosion Science and Technology
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• 제12권2호
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• pp.85-92
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• 2013

This work is concerned with an evaluation of dynamic boric acid corrosion (BAC) of low alloy steel for reactor pressure vessel of a pressurized water reactor (PWR). Mockup test method was newly established to investigate dynamic BAC of the low alloy steel under various conditions simulating a primary water leakage incident. The average corrosion rate was measured from the weight loss of the low alloy steel specimen, and the maximum corrosion rate was obtained by the surface profilometry after the mockup test. The corrosion rates increased with the rise of the leakage rate of the primary water containing boric acid, and the presence of oxygen dissolved in the primary water also accelerated the corrosion. From the specimen surface analysis, it was found that typical flow-accelerated corrosion and jet-impingement occurred under two-phase fluid of water droplet and steam environment. The maximum corrosion rate was determined as 5.97 mm/year at the leakage rate of 20 cc/min of the primary water with a saturated content of oxygen within the range of experimental condition of this work.

• Membrane and Water Treatment
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• 제10권3호
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• pp.201-206
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• 2019

In this study, we performed an electrowinning process for effective removal of metals (Cu and Ni) in solution and their recovery as solid forms. A complete removal of Cu and Ni (1,000 mg/L) was observed during four times recycling test, indicating that our electrowinning system can ensure the efficient metal removal with high stability and durability. In addition, we investigated effect of operation parameters (i.e., concentration of boric acid only for Ni, variation of pH, concentration of electrolyte ($H_2SO_4$), and cell voltage) on the efficiency of metal removal (Cu and Ni) during the electrowinning. The addition of boric acid significantly enhanced removal efficiency of Ni as the concentration of boric acid increased up to 10 g/L. Compared to negligible pH effect (pH 1, 2, and 4) on the Cu removal, we observed the increase in removal efficiency of Ni as the pH increased from 1 to 4. The electrolyte concentration did not significantly influence the removal of Cu and Ni in this study. We also obtained great removal rates of Cu and Ni at 2.5 V and 4.0 V, which were much faster than those at lower voltages. Finally, almost 99% of each Cu and Ni (1,000 mg/L) was selectively removed from the mixture of metals by adjusting pH and addition of boric acid after the completion of Cu removal. The findings in this study can provide a fundamental knowledge about effect of important parameters on the efficiency of metal recovery during the electrowinning.

• 방사선산업학회지
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• 제18권2호
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• pp.147-153
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• 2024

Radioactive liquid waste generated during operation and overhaul is collected and reused through the radioactive liquid waste treatment system and continuous monitoring system in the nuclear power plant or discharged to the outside if it satisfies the limit within the control and monitoring. However, there are concerns about boric acid management, which controls the power output of nuclear power plants in radioactive liquid waste. Due to the behavior of boric acid, it is difficult to remove it in the existing liquid radwaste system, and the concentration of boric acid water discharged tends to be higher than the natural state of 5 ppm, so additional facilities should be considered. Therefore, this study aims to evaluate the radiological effects of radioactive waste treatment facilities that are under development and use them as a basis for managing worker exposure and evaluating the safety of facilities in the future.

• Nuclear Engineering and Technology
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• 제52권9호
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• pp.1939-1944
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• 2020

Pool boiling heat transfer of a copper microporous coating was experimentally studied in borated water with a concentration of boric acid from 0.0 to 5.0 vol percent (vol%) to determine the effect of boric acid on boiling heat transfer in water. A high-temperature, thermally conductive microporous coating (HTCMC) was created by sintering copper powder with an average particle size of 67 ㎛ onto a 1 cm × 1 cm plain copper surface with a coating thickness of ~300 ㎛ within a furnace in a vacuum environment. The tests showed that the nucleate boiling heat transfer coefficient (NBHT) of HTCMC became slightly less enhanced as the concentration of boric acid increased but the NBHT coefficient values were still significantly higher than those of the plain surface. The critical heat flux (CHF) values from 0 to 1.0 vol% were maintained at ~2,000 kW/㎡, and then, they gradually decreased down to ~1,700 kW/㎡ as the concentration increased further to 5.0 vol%. It is believed that the micro-scale pores of the HTCMC were partially blocked by the high boric acid concentration during the nucleate boiling such that the small bubbles were not effectively created using the HTCMC reentrant cavities as the boric acid concentration increased.

• KSBB Journal
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• 제14권1호
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• pp.51-57
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• 1999

양어장 순환수 속의 암모니아성 질소를 제거하기 위하여 PVA를 boric acid. 처리법과 ethanol 처리법 및 freezing-thawing 처리법으로 제조된 구형 bead와 칼럼형 bead에 이들을 이용한 질화균군을 고정화 시켰다. 유가식 배양에서는 boric acid 처리법으로 제조된 구형 bead가 유동층 반응조에서 사용하기에 성상면에서나 암모니아 제거율에서 가장 이상적이었으며, 90일 동안의 유동층 반응기에서 운전하였으나 bead의 성상이나 효율은 변화없이 일정하였다. Boric acid 처리법으로 제조된 bead를 충전한 연속 빈용기에서의 암모니아성 질소 제거에 대한 실험에서 수리학적 체류시간이 0.6시간에서 암모니아 제거 속도는 31.9g $NH__3-N/m^3$/day였으며 제거효울은 36% 였다. 연속 반응기내에 2mg/L의 암모니아가 주입되고 공기량을 0.1vvin으로 공급하더라도 용존산소 농도를 4,64~5.40mg/L로 유지할수 있었으므로 질산화에 필요한 용존산소를 충분히 유지할 수가 있는 것으로 나타났으며 pH는 7.7~7.9의 범위를 유지할 수가 있어 pH에 따른 위해 요소는 없는 것으로 나타났다.

• 한국표면공학회지
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• 제4권1호
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• pp.5-15
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• 1971

"Rapid Determination of Boric Acid in Nickel Plating Solution" by the addition of Na$_2$C$_2$O$_4$ and thus preventing the precipitation of i(OH)$_2$ during titiration , has previously been reported. In this paper, the exact amount of glycerine and the complexing possibility of oxalate with nickel has been determined by measn of conductivity titrations. This experimental work has been supported by the mathematical application of the Debye-Huckel and mass action equitions as well as statistical analysis. The results were ; (1) Fro determining boric acid in nickel plating solution, 20 ml of 400ml/ι glycerine was sufficient, since 97% of the H$_3$BO$_3$ was dissoicated by this addition. (2) In the absence of Na$_2$C$_2$O$_4$ the continious precipitation of Ni(OH)$_2$ during titration with NaOH even past end -point for boric acid determination resulted in considerable anlaytical error. (3) In the presence of Na$_2$C$_2$O$_4$ during titration , Ni++ combined with C$_2$O$_4$-to form NiC$_2$O$_4$. The solution with this precititate of very fine, colloidal , trantsparent particles, remained quite clear for approximately 2 hours. Therefore it was shown that the presence of Na$_2$C$_2$O$_4$ prevents the formation of gross Ni(OH)$_2$ precititation by forming NiC$_2$O$_4$ instead of a complex salt with Ni++ , which did not interfere with the visible determination of the end point for boric acid with NaOH titation. This observous may be interpreted in the light of the previously published solubility ratio for NiC$_2$O$_4$ and Ni(OH)$_2$, 0.3mg/100g H$_2$O(25$^{\circ}C$), respectively. Precipitation of the less soluble , albeit transparent salt, NiC$_2$O$_4$ precluded therefore the precipitation of the Ni(OH)$_2$ salt.

• 한국재료학회지
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• 제9권4호
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• pp.414-418
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• 1999

Typical metal oxide thin films having optical and electrical properties are widely used as inorganic functional materials. Liquid phase deposition(LPD) method, a new low temperature process, has been developed for the several advantages of no vacuum system, low cost, high throughput, and low processing temperature(<$50^{\circ}C$). Silica powder was added to 40wt% hydrofluoro-silicic acid($H_2$SiF\ulcorner) to obtain an immersing solution of silica-saturated hydrofluorosilicic acid solution. Boric acid solution was continuously added in the range from 0 to 0.05M to prepare supersaturated hydrofluorosilicic acid solution. LPD $SiL_2$film was formed with the variation of added amount of $H_2$O. The SiO$_2$thin film could be prepared from hydrofluorosilicic acid by LPD method. The thickness of LPD $_SiO2$film was influenced by the boric acid concentration and added amount of $H_2$O. Silicon in thin film existed as SiF\ulcorner by Raman spectrum.