• Nuclear Engineering and Technology
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• 제52권6호
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• pp.1222-1230
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• 2020

The corrosion rates of the reactor pressure vessel materials of SA508 Grade 3 were measured using a weight loss method in aerated boric acid solutions to simulate the evaporation of leaked PWR primary water in an ambient environment. The corrosion behavior and products were examined using X-ray diffraction and electron microscopy. SA508 showed typical general corrosion characteristics. The corrosion rate increased steadily as the boron concentration was increased. As the immersion time elapsed, the corrosion rate slowly or rapidly decreased according to the oxidation reaction of iron. The corrosion rate showed a complicated pattern depending on the temperature; it increased gradually and then rapidly decreased again when reaching a certain transition temperature. The corrosion products of SA508 were found to be FeO(OH), Fe₂O₃, and Fe₃O₄. As the boron concentration decreased and the temperature was increased, the formation of Fe₃O₄ was more favorable as compared to the formation of FeO(OH) and Fe₂O₃. Consequently, the changes of the corrosion rate and behavior were closely related to the oxidation reaction of iron on the surface. The corrosive damage to SA508 appears to be most severe when the oxidation reaction is such that Fe₂O₃ forms as a corrosion product.

• 분석과학
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• 제14권1호
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• pp.34-43
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• 2001

수소화물생성법-유도결합플라스마-원자방출분광법으로 게르마늄을 분석할 때 보조산으로 phosphoric acid의 사용은 nitric acid, hydrochloric acid, sulfuric acid, perchloric acid, boric acid, tartaric acid, malic acid, oxalic acid, acetic acid, tannic acid, citric acid의 사용보다 높은 수소화물 생성효율을 보였고, 같은 pH영역이라도 phosphate ion이 존재하는 buffer의 사용이 더 높은 생성효율을 보였다. 또한, 2.5M phosphoric acid를 이용한 결과, 시료용액 내에 잔류하는 산이나 공존원소의 영향이 감소하였다. 환원제와 안정제의 농도가 증가할수록 수소화물 생성효율은 증가되었으며, 최대방출세기를 나타내는 산의 세기는 높은 쪽으로 이동했고 농도영역은 넓어졌다. 인산 존재 하에서의 게르마늄의 검출한계는 $0.03{\mu}g/L$이었다.

• 한국화재소방학회논문지
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• 제32권2호
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• pp.1-6
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• 2018

붕산과 5붕산암모늄으로 처리한 편백나무 시험편의 연소특성에 관한 실험을 ISO 5660-1 표준에 따른 콘칼로리미터를 이용하여 수행하였다. 그 결과 붕산과 5붕산암모늄의 혼합된 투여는 그들의 시너지 효과에 의해 화재성능지수 값을 향상시켰다. 또한 붕소 화합물로 처리한 시험편은 공시편보다 총열방출율 값이 6.1~14.1% 감소되었다. 붕소화합물로 처리된 시편의 총연기방출율은 연소과정 전반에 걸쳐 감소되었으나 붕산/5붕산암모늄은 예외였다. 일산화탄소 최대농도는 15.8~25.5% 정도 감소하는 경향성이 있었다. 대체적으로 난연제로 처리한 목재는 화재 위험성이 낮아진 것으로 이해된다.

• 한국작물학회지
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• 제41권4호
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• pp.441-449
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• 1996

붕소의 엽면살포에 따른 참깨의 생육, 수량 및 여러 형질의 변화를 구명하고자 평휴, 휴고(15cm) 처리별로 구분하고, 붕소의 농도를 무살포, 0.2%, 0.4%별로 주경 11절기에 각각 전엽면에 살포하였던 결과를 요약하면 다음과 같다. 1. 붕소 살포에 의한 엽면적의 증가는 평휴, 휴고 15cm모두 농도 증가에 비례하여 5절엽과 11절엽에서 증가 효과를 나타냈고, 경태는 평휴에서만이 붕소 엽면살포 농도에 비례하여 증가하였으며, 지상부 건경엽중은 붕소 엽면살포에 의하여 평휴, 휴고 15cm 모두 증가효과를 가져왔다. 2. 주당 꼬투리수는 평휴에서만이 붕소 엽면살포 농도에 비례하여 증가하였고, 1,000립중은 평휴 처리시 중단부위 이하의 꼬투리에서 붕소살포농도와 비례적으로 무거워진 경향이었으나, 휴고 15cm에서는 0.2% 농도에서 만이 증가경향을 나타냈다. 3. 종실중은 평휴, 휴고 15cm 처리 모두 붕소 살포농도가 증가할수록 건경엽중, 주당 꼬투리수, 1,000립중 등의 증가로 증수되었고, 이 경향은 평휴에서 현저하였다. 4. 붕소 엽면살포 효과를 절위별 꼬투리내 종실중비로서 보면 상단부위의 종실중은 평휴보다 휴고 15cm에서 7%가 무거워진 경향이었고, 붕소 엽면살포에 의한 종실중 증가와 유관한 형질들은 평휴 처리시 엽면적, 경태, 주당 꼬투리수 및 중단부 이하의 천립중 등이었고, 휴고 15cm 처리시는 건경엽중 뿐이었다. 5. 붕소 엽면살포에 의한 여러 형질들 간의 상호관계를 보면 평휴에서 경태는 엽면적 및 하단부위의 천립중과 그리고 엽면적은 주당 꼬투리수, 건물중 및 중단부 이하의 천립중 등과, 건물중은 중단부 이하의 천립중과 유관하였으나, 평휴 15cm는 엽면적과 주당 꼬투리수 간에 비례적인 상호관계가 있을 뿐이었다.서 높았으며, 두처리 모두 시비수준이 높을수록 높았으나, 무경운재배에 비하여 경운재배에서는 시일의 경과에 따라서도 차이가 크지 않았고 함량도 낮았다. 6. 양이온함량은 모두 경운 유 ㆍ무에 관계없이 시비수준이 높을수록 높은 경향을 보였고, 10일에 최고수준을 보인 후 완만한 감소를 나타냈으며, $K^{+}$, $Ca^{2+}$에 비해 $Mg^{2+}$이 보다 낮은 함량을 보였다.989년산 일반계를 10분도와 12분도로 도정하였을 때 도정도에 따른 밥맛의 차이는 없었다.X>$CoO_x$는 $Co_3O_4$로 존재하고, 반응 전의 경우에는 이와는 다른 chemical state를 보여주었다. XRD 및 XPS 결과를 바탕으로, 촉매표면에 존재하는 $Co_3O_4$의 외부표면이 $Co_2TiO_4$와 $CoTiO_3$ 같은 $CoTiO_x$로 encapsulation되어 있는 모델구조를 제안할 수 있고, 이는 반응시간의 함수로 나타나는 촉매활성에 있어서 전이영역의 존재를 잘 설명할 수 있을 뿐만 아니라, XRD와 XPS에서 얻어진 촉매의 물리화학적인 특성을 잘 반영할 수 있다. 나타냈고, 골격근과 눈 조직에서 피루브산에 대한 LDH의 친화력이 상당히 크므로 LDH가 혐기적 조건에서 효율적으로 기능을 하는 것으로 사료된다.5) and "Cleanliness of clothes ＆ features" (p ＜0.05) of VIP ward were significantly higher than those of a general ward.tive to apply.아울러 고려(考慮)해야 한다

• 분석과학
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• 제14권5호
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• pp.416-421
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• 2001

수소화물 발생 유도결합 플라스마 원자 방출 분광법으로 주석을 분석할 때 연속 흐름 수소화물 발생 장치에 사용되는 환원제 및 산의 농도에 대하여 최적조건을 확립하였다. 시료에 함유되어 있는 플루오르화 이온이 주석의 수소화물 발생을 방해하는 영향과 이러한 영향을 최소화하기 위한 여러 가지 예비환원제를 비교 실험하였다. 환원제 및 안정제의 농도가 $NaBH_4$ 1~2%/NaOH 1.0 M인 조건에서 우수한 수소화물을 발생시키는 산농도는 0.5~1.0 M 이었으며, 또한 플루오르화 이온의 방해영향이 매우 크게 관찰되었지만 boric acid 및 L-cysteine의 혼합용액은 이런 영향을 최소화하여 가장 효과적인 주석의 수소화물 발생 보조제로 확인되었다. 플루오르화 이온이 함유되어 있는 용액에서 미량의 주석을 분석하여 회수율이 100~108 %의 결과를 얻었다.

• Nuclear Engineering and Technology
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• 제47권4호
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• pp.434-442
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• 2015

The advanced passive pressurized water reactor (PWR) is being constructed in China and the passive residual heat removal (PRHR) system was designed to remove the decay heat. During accident scenarios with increase of heat removal from the primary coolant system, the actuation of the PRHR will enhance the cooldown of the primary coolant system. There is a risk of power excursion during the cooldown of the primary coolant system. Therefore, it is necessary to analyze the thermal hydraulic behavior of the reactor coolant system (RCS) at this condition. The advanced passive PWR model, including major components in the RCS, is built by SCDAP/RELAP5 code. The thermal hydraulic behavior of the core is studied for two typical accident sequences with PRHR actuation to investigate the core cooling capability with conservative assumptions, a main steam line break (MSLB) event and inadvertent opening of a steam generator (SG) safety valve event. The results show that the core is ultimately shut down by the boric acid solution delivered by Core Makeup Tank (CMT) injections. The effects of CMT boric acid concentration and the activation delay time on accident consequences are analyzed for MSLB, which shows that there is no consequential damage to the fuel or reactor coolant system in the selected conditions.

• 한국표면공학회지
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• 제50권6호
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• pp.523-530
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• 2017

In this study, we developed the h-BN interphase for ceramic matrix composites (CMCs) through a wet chemical coating method, which has excellent price competitiveness and is a simple process as a departure from the existing high cost chemical vapor deposition method. The optimum condition for nitriding an h-BN interphase using boric acid and urea as precursors were derived, and the h-BN interphase coating through a wet method on a carbon preform of 2.5 D was conducted to apply the optimum conditions to the CMCs. In order to control the coating property via the wet coating method, four parameters were investigated such as dipping time of the specimen in the precursor solution, the ratio of boric acid and urea in the precursor, the concentration of solution where the precursor was dissolved, and the cycle of dipping and dry process. The CMCs was fabricated through polymer impregnation and pyrolysis (PIP) processes and a three-point flexural strength test was conducted to verify the role of the coated h-BN interphase.

• Journal of the Korean Wood Science and Technology
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• 제52권2호
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• pp.157-174
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• 2024

This study investigates the influence of varying concentrations of boric acid (BA) preservative on the physical and mechanical properties of light red meranti (LRM) found in Sarawak. LRM or Shorea leprosula samples were treated with various concentrations of BA via the dip diffusion method using American Society for Testing and Materials (ASTM) standards. The physical property, particularly the retention rate and mechanical properties, bending strength, modulus of elasticity (MOE), tensile and compression strength parallel to grain of impregnated and control samples were tested to determine the effects of BA preservative. The retention rate was found to increase with increasing BA concentration and higher surface area to volume ratio. The mechanical properties in terms of the MOE and tensile strength parallel to grain were found to be greater than those of the control samples, whereas the bending strength and tensile strength parallel to grain were lower. Amongst the results, only the retention rate and MOE showed significant interaction effects at 5% level of significance between all factors tested (samples size and BA concentration for retention rate and BA concentration for MOE).

• 생명과학회지
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• 제10권6호
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• pp.558-563
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• 2000

Effect of inhibitors on Vibrio parahaemolyticus cell growth and its urease activity was studied. The growth of the bacterium and the enzyme activity were inhibited by the addition of 0.02% p-hydroxymercuric benzoate, $HgCl_2$and $AgNO_3$. However, same concentration of boric acid, thallium acetate and $Pb(NO_3)_2$ did not affect the cell growth but inhibited urease activity by 25%, 29%, and 38%, respectively. Acetohydroxamic acid was the most potent inhibitor on cell growth by inhibiting 40% but did not affect urease activity. To investigate the effect of inhibitors on urease activity, urease was purified and confirmed on SDS-PAGE. The purified urease was inhibited 100% by the addition of 1 mM acetohydroxamic acid and $AgNO_3$but no inhibition was occurred by the addition of the same concentration of thallium acetate. and the addition of 0.01 mM of $HgCl_2$ and acetohydroxamic acid inhibited the purified urease activity by 39% and 24%, respectively. On 0.1 millimolar basic, acetohydroxamic acid and $HgCl_2$inhibited 4 times more active in urease inhibition than p-hydroxymercuric benzoate whereas no inhibition was occurred either thallium acetate or $Pb(NO_3)_2$.

• Nuclear Engineering and Technology
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• 제44권4호
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• pp.369-378
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• 2012

A load-following operation in APR+ nuclear plants is necessary to reduce the need to adjust the boric acid concentration and to efficiently control the control rods for flexible operation. In particular, a disproportion in the axial flux distribution, which is normally caused by a load-following operation in a reactor core, causes xenon oscillation because the absorption cross-section of xenon is extremely large and its effects in a reactor are delayed by the iodine precursor. A model predictive control (MPC) method was used to design an automatic load-following controller for the integrated thermal power level and axial shape index (ASI) control for APR+ nuclear plants. Some tracking controllers employ the current tracking command only. On the other hand, the MPC can achieve better tracking performance because it considers future commands in addition to the current tracking command. The basic concept of the MPC is to solve an optimization problem for generating finite future control inputs at the current time and to implement as the current control input only the first control input among the solutions of the finite time steps. At the next time step, the procedure to solve the optimization problem is then repeated. The support vector regression (SVR) model that is used widely for function approximation problems is used to predict the future outputs based on previous inputs and outputs. In addition, a genetic algorithm is employed to minimize the objective function of a MPC control algorithm with multiple constraints. The power level and ASI are controlled by regulating the control banks and part-strength control banks together with an automatic adjustment of the boric acid concentration. The 3-dimensional MASTER code, which models APR+ nuclear plants, is interfaced to the proposed controller to confirm the performance of the controlling reactor power level and ASI. Numerical simulations showed that the proposed controller exhibits very fast tracking responses.