• 한국토양비료학회지
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• 제37권6호
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• pp.378-382
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• 2004

Soil pH is an important indicator for soil reactions and crop growth. pH buffer capacity and lime requirements are necessary to comprehend and manage soils well. The characteristics related with soil pH were analyzed and 5 field trials were conducted to elucidate pH buffer capacity of soil and lime requirements and liming factor for Korean acid soils. Soil minerals were analyzed for the soil of 2 years after treating $CaCO_3$ using X-ray diffraction. The amount of neutralized $H^+$ was regarded as the exchangeable aluminium overcoming ${\Delta}pH$, because pH buffer capacity of soil depended on exchangeable aluminium. Lime requirement was somewhat similar to the KCl exchangeable aluminium and it was also affected by the exchangeable cation by added lime. X-ray diffraction analyses revealed that an aluminium dissociation from Korean acid soils was equilibrated with kaolin minerals and changed into anorthite ($CaAl_2Si_2O_8$) by neutralizing with $CaCO_3$. Neutralizing process was composed of changing process of $Al^{3+}$ into $H^+$ and $Al(OH)_4{^-}$ ionic species and of neutralizing $H^+$ by, the amount of which was lime requirement. The fact that anorthite dissociates an aluminium ion higher than kaolinite does enabled to consider a liming factor (LF) the content of exchangeable cation and ${\Delta}pH$, $LF=1.5+0.2{\times}{\sum} Cations{\times}{\Delta}pH$.

• Wind and Structures
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• 제39권1호
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• pp.15-30
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• 2024

In this paper, detailed wind field data of the full path of typhoon "Bailu" were obtained based on site measurements. Typhoon "Bailu" made first landfall southeast of the Taiwan Strait with a wind speed of approximately 30 m/s near the center of the typhoon eye and a second landfall in Dongshang County in Fujian Province. The moving process is classified into 3 regions for analysis and comparison. Detailed analyses of wind characteristics including wind profile, turbulence intensity, gust factor, turbulence integral scale and wind power spectral density function at the full process of the typhoon are conducted, and the findings are presented in this paper. Wind speed shows significant dependence on both the direction of the moving path and the distance between the typhoon center and measurement site. Wind characteristics significantly vary with the moving path of the typhoon center. The relationship between turbulence intensity and gust factor at different regions is investigated. The integral turbulence scales and wind speed are fitted by a Gaussian model. Such analysis and conclusions may provide guidance for future bridge wind-resistant design in engineering applications.

• Nuclear Engineering and Technology
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• 제56권10호
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• pp.4390-4396
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• 2024

The response of an anti-Compton phoswich detector to gamma rays was investigated using Monte-Carlo method, and the pulses from different crystal cases, including gamma deposition only in the LaBr3(Ce) or CsI(Tl) crystal and coincidence in both crystals, were analyzed. A novel pulse discrimination method for gamma deposition events based on wavelet transform analysis, called SSD (Scale Shape Discrimination), was developed in this study. Compared to the traditional PSD (Pulse Shape Discrimination) method, SSD has the advantage of transforming one-dimensional pulses in the time-domain into two-dimensional time-frequency spectra, providing the more useful features for pulse discrimination. The performances of the Compton suppression and Full-energy peak loss using PSD and SSD methods was studied. The results show that the Compton suppression factor I_PSD = 5.12 and I_SSD = 5.32, and FEP loss factor PL_PSD = 0.0554 and PL_SSD = 0.0587. Meanwhile, the influences of the cutoff values for pulse discrimination on the results of I and PL with different method were analyzed.

• Structural Engineering and Mechanics
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• 제71권4호
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• pp.391-405
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• 2019

Compared to the ambient vibration test mainly identifying the structural modal parameters, such as frequency, damping and mode shapes, the impact testing, which benefits from measuring both impacting forces and structural responses, has the merit to identify not only the structural modal parameters but also more detailed structural parameters, in particular flexibility. However, in traditional impact tests, an impacting hammer or artificial excitation device is employed, which restricts the efficiency of tests on various bridge structures. To resolve this problem, we propose a new method whereby a moving vehicle is taken as a continuous exciter and develop a corresponding flexibility identification theory, in which the continuous wheel forces induced by the moving vehicle is considered as structural input and the acceleration response of the bridge as the output, thus a structural flexibility matrix can be identified and then structural deflections of the bridge under arbitrary static loads can be predicted. The proposed method is more convenient, time-saving and cost-effective compared with traditional impact tests. However, because the proposed test produces a spatially continuous force while classical impact forces are spatially discrete, a new flexibility identification theory is required, and a novel structural identification method involving with equivalent load distribution, the enhanced Frequency Response Function (eFRFs) construction and modal scaling factor identification is proposed to make use of the continuous excitation force to identify the basic modal parameters as well as the structural flexibility. Laboratory and numerical examples are given, which validate the effectiveness of the proposed method. Furthermore, parametric analysis including road roughness, vehicle speed, vehicle weight, vehicle's stiffness and damping are conducted and the results obtained demonstrate that the developed method has strong robustness except that the relative error increases with the increase of measurement noise.

• Journal of Microbiology and Biotechnology
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• 제25권12호
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• pp.2116-2124
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• 2015

To understand the effects of physicochemical factors on nitrite transformation by microalgae, a lipid-rich Chlorella with high nitrite tolerance was cultured with 8 mmol/l sodium nitrite as sole nitrogen source under different conditions. The results showed that nitrite transformation was mainly dependent on the metabolic activities of algal cells rather than oxidation of nitrite by dissolved oxygen. Light intensity, temperature, pH, NaHCO₃ concentrations, and initial cell densities had significant effects on the rate of nitrite transformation. Single-factor experiments revealed that the optimum conditions for nitrite transformation were light intensity: 300 μmol/m²/s; temperature: 30℃ pH: 7-8; NaHCO₃ concentration: 2.0 g/l; and initial cell density: 0.15 g/l; and the highest nitrite transformation rate of 1.36 mmol/l/d was achieved. There was a positive correlation between nitrite transformation rate and the growth of Chlorella. The relationship between nitrite transformation rate (mg/l/d) and biomass productivity (g/l/d) could be described by the regression equation y = 61.3x (R² = 0.9665), meaning that 61.3 mg N element was assimilated by 1.0 g dry biomass on average, which indicated that the nitrite transformation is a process of consuming nitrite as nitrogen source by Chlorella. The results demonstrated that the Chlorella suspension was able to assimilate nitrite efficiently, which implied the feasibility of using flue gas for mass production of Chlorella without preliminary removal of NO_X.

• Journal of Microbiology and Biotechnology
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• 제23권4호
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• pp.539-544
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• 2013

The effects of culture depth (2-10 cm) and cell density on the growth rate and biomass productivity of Chlorella sp. XQ-200419 were investigated through the use of a self-designed open circular pond photobioreactor-imitation system. With increases in culture depths from 2 to 10 cm, the growth rate decreased significantly from 1.08 /d to 0.39 /d. However, the biomass productivity only increased slightly from 8.41 to 11.22 $g/m^2/d$. The biomass productivity (11.08 $g/m^2/d$) achieved in 4 cm culture with an initial $OD_{540}$ of 0.95 was similar to that achieved in 10 cm culture with an initial $OD_{540}$ of 0.5. In addition, the duration of maximal areal productivity at a 4 cm depth was prolonged from 1 to 4 days, a finding that was also similar to that of the culture at a 10 cm depth. In both cases, the initial areal biomass densities were identical. Based on these results and previous studies, it can be concluded that the influence of culture depth and cell density on areal biomass productivity is actually due to different areal biomass densities. Under suitable conditions, there are a range of optimal biomass densities, and areal biomass productivity reaches its maximum when the biomass density is within these optimal ranges. Otherwise, biomass productivity will decrease. Therefore, a key factor for high biomass productivity is to maintain an optimal biomass density.

• Geomechanics and Engineering
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• 제19권1호
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• pp.49-60
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• 2019

Crack instability propagation during coal and rock mass failure is the main reason for electromagnetic radiation (EMR) generation. However, original cracks on coal and rock mass are hard to study, making it complex to reveal EMR laws and mechanisms. In this paper, we prefabricated cracks of different inclinations in coal and rock samples as the analogues of the native cracks, carried out uniaxial compression experiments using these coal and rock samples, explored, the effects of the prefabricated cracks on EMR laws, and verified these laws by measuring the surface potential signals. The results show that prefabricated cracks are the main factor leading to the failure of coal and rock samples. When the inclination between the prefabricated crack and axial stress is smaller, the wing cracks occur first from the two tips of the prefabricated crack and expand to shear cracks or coplanar secondary cracks whose advance directions are coplanar or nearly coplanar with the prefabricated crack's direction. The sample failure is mainly due to the composited tensile and shear destructions of the wing cracks. When the inclination becomes bigger, the wing cracks appear at the early stage, extend to the direction of the maximum principal stress, and eventually run through both ends of the sample, resulting in the sample's tensile failure. The effect of prefabricated cracks of different inclinations on electromagnetic (EM) signals is different. For samples with prefabricated cracks of smaller inclination, EMR is mainly generated due to the variable motion of free charges generated due to crushing, friction, and slippage between the crack walls. For samples with larger inclination, EMR is generated due to friction and slippage in between the crack walls as well as the charge separation caused by tensile extension at the cracks' tips before sample failure. These conclusions are further verified by the surface potential distribution during the loading process.

• 한국토양비료학회지
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• 제7권3호
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• pp.185-191
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• 1974

치환성(置換性) Al 함량(含量)에 근거(根據)한 석회소요량결정방법(石灰所要量決定方法)을 우리나라 밭 토양(土壤)에 대(對)하여 검토(檢討)한 목적(目的)으로 실내(室內) 및 Pot시험(試驗)을 실시(實施)하였던 바 그 결과(結果)는 다음과 같다. 1. 공시(供試)된 반토양(土壤)의 pH는 5.0-5.4이었고 치환성(置換性) Al함량(含量)은 1.1~3.0me/100g 범위(範圍)에 있어 경작년도(耕作年度)가 오래된 토양(土壤)일수록 그 함량(含量)은 적었다. 2. 항온(恒溫) 실험결과(實驗結果)에서 광질토양(鑛質土壤)에 있어서는 치환성(置換性) Al의 100% 상당하는 당량(當量)의 중화석회량(中和石灰量) (토양별 소석회량(消石灰量) 범위(範圍)는 45~122kg/10a)으로 대부분의 Al이 중화(中和)되어 Al 중화비율(中和比率)은 평균(平均)95% 이었으나 화산회토양(火山灰土壤)에서는 200%의 중화석회량(中和石灰量)으로도 치환성(置換性) Al이 66.5% 만이 중화(中和)되어 더욱 많은 량(量)(100% 중화량(中和量)외 약(約) 3 배(倍))의 석회(石灰)를 요구(要究)하였다. 3. 광질토양(鑛質土壤)에서는 95%의 치환성(置換性) Al이 중화(中和)되었을 때 평균(平均) pH는 5.2에서 6.3으로 높아졌으며 화산회토양(火山灰土壤)에서는 치환성(置換性) Al의 200% 중화석회량가용(中和石灰量加用)으로 pH는 5.3에서 5.5로 변화(變化)되었을 뿐이었다. 4. 치환성(置換性) Al과 치환산도(置換酸度)($y_1$)의 두 측정치(測定値)(me 단위(單位)) 간(間)에는 r=0.99로서 고도(高度)의 상관관계(相關關係)가 있었으므로 치환산도(置換酸度)는 주로 치환성(置換性) Al에 기인(起因)된 것이라는 사실(事實)을 확인(確認)하였다. 5. 야산지토양(野山地土壤)인 송정통(松亭統) 표토(表土)에 콩을 재배(栽培)한 Pot시험(試驗)에서 인산흡수계수(燐酸吸收係數)의 5% 상당(相當)의 인산(燐酸)(32.1kg/10a)을 중과석(重過石)과 용성인비(熔成燐肥)로 시용(施用)했을 때 치환산도(置換酸度)를 기준한 최적석회소요량(最適石灰所要量)(me) 산출(算出)을 위(爲)한 Liming factor는 중과석(重過石) 1.132, 용성인비(熔成燐肥) 0.594이었고 작물생육(作物生育)을 위한 최적(最適) pH는 6.0 부근이었으며 최적(最適) Al의 중화비율(中和比率)은 80~90% 이었음을 보여 주었다.

• 한국토양비료학회지
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• 제33권6호
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• pp.405-415
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• 2000

본 연구는 황 원소를 이용하여 시설재배지의 일부 토양에서 나타나는 알칼리 반응을 교정하고자 실시하였다. 황 원소의 산화와 토양 pH에 미치는 효과를 살펴보기 위하여 토양 pH 8.3을 6.3으로 낮추는데 소요되는 황 시용량을 완충곡선으로부터 계산하여 황 소요량의 1~10배 수준까지 첨가하고 50% water holding capacity에 해당하는 수분을 가한 다음, $30^{\circ}C$로 유지되는 항온실에서 정치하였다. Incubation 동안 1주 간격으로 토양 pH 및 sulfate-S의 생성량을 조사한 결과, 토양 pH는 최초의 8.3에서 4~6주 사이에는 목표 pH인 6.3 부근으로 감소하였고, 이 때의 sulfat-S의 생성율은 100%를 상회하여 완충곡선법을 이용한 황 시용량 결정법이 적절함을 확인하였다. Pot 재배시험 결과, 중화량에 해당하는 황시용구의 토양 pH는 중성부근에 이르렀으나 상추수량은 무처리구와 차이가 없었으며, 목표 pH로 낮추기 위한 황 소요량의 약 3배 이상 과량 첨가한 처리구의 토양 pH는 4.8 수준으로 급격히 감소하고 토양중 추출성 미량원소의 농도가 증가하여 상추 수량은 현저히 감소하는 한편, 식물체중 N/S비율의 감소가 나타나 과다한 황 시용으로 토양 양분의 불균형화 및 작물의 수량감소를 초래하였다. 따라서 토양 pH 조정을 목적으로 황 원소를 시용할 경우 정확한 시용량을 준수하고, 토양에 존재하는 기존의 sulfate-S 농도가 높을 경우에는 분시를 통하여 토양내 sulfate-S 농도가 일시적으로 크게 증가하지 않도록 관리해야 할 것으로 판단되었다. 또한 liming의 경우 포장에서는 실내나 pot 조건과 다르게 포장의 석회인자(Liming factor)를 구하여 석회시용량을 조절하는 것과 같이 토양의 pH를 낮추는 경우도 포장의 acidifying factor에 관한 별도의 연구가 필요할 것으로 생각된다. 한편 완충곡선법을 이용한 황 시용량 결정법을 보다 단순화하기 위하여 0.1N-HCl을 이용한 완충곡선법을 고안하였으며, 이 방법은 토양산도를 목표 pH까지 저감시키는데 소요되는 0.1N-HCl의 량을 구하여 제안된 계산식에 적용하면 쉽게 황 소요량을 구할 수 있으므로 알칼리성 토양 상토 및 호산성 작물재배토양의 pH조정에 이용 가능할 것이다.

• 한국토양비료학회지
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• 제7권1호
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• pp.29-34
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• 1974

호남(湖南) 야산(野山)에 널리 포(布)되어 있는 적황색(赤黃色) 토양(土壤)(송정통(松汀統))의 비옥토(肥沃土)를 증진(增進)시키기 위하여 각종(各種) 개량제(改良劑)(석회(石灰), 용인(熔燐), 퇴비(堆肥), 생고(生藁) 등(等))를 시용(施用)하여 시험(試驗)을 실시(實施)한 결과(結果)는 다음과 같이 요약(要約)할 수 있었다. 1. 신(新) 개간지(開墾地) 토양개량(土壤改良) 및 수량증대(收量增大)를 위(爲)해 시용(施用)한 퇴비(堆肥)+석회(石灰)+용인(熔燐)(인산흡수계수(燐酸吸收係數) 5% 조절(調節))구(區)에서 수량(收量)이 제일 높았고 표준구(標準區)(N6 P9 K6)에 비(比)하여 93.3% 증수(增收)되었으며 용인(熔燐) 단용구(單用區)(인후흡수계수(燐後吸收係數) 5% 조절구(調節區))에서도 표준구(標準區)에 비(比)하여 62.7%증수(增收)되었다. 2. 토양분석(土壤分析) 결과(結果) pH는 무석회구(無石灰區)인 3요소표준구(三要素標準區)와 NK 용인구(熔燐區)를 제외(除外)하고는 각구(各區) 공(共)히 원래(原來) pH 5.5에서 6.5 이상(以上)으로 증가(增加)되었고 인산(燐酸)은 시험전(試驗前) 27 ppm에 비(比)하여 인산(燐酸)을 증시(增施)하지 않은 구(區) (3요소표준구(3要素標準區)와 3요소(要素) 석회(石灰))를 제외(除外)하고는 각구(各區) 공(共)히 대두(大豆) 개화(開花): 30일(日) 후(後)엔 200 ppm 내외(內外)로 증가(增加)되었으나 대두(大豆) 수확후(收穫後) 토양중(土壤中)에 100 ppm 내외(內外)로 떨어져 기대(期待) 수준(水準)인 200 ppm 미달(未達)이었다. 유기물(有機物)은 1,000kg/10a 시용구(施用區)에서도 대두수확수(大豆收穫後) 1.7%로써 부식(腐植) 증가(增加)에는 0.8% 불과(不過)했고 이상적(理想的)인 유기물(有機物) 3.5%에 도달(到達)하기에는 장기(長期) 다량시용(多量施用)이 요구(要求)되며 염기(鹽基) 치환용량(置換容量)은 시험전(試驗前) 7.24me/100g였으나 수확후(收穫後) 석회퇴비(石灰堆肥), 인용(燐熔), 3요소(要素) 처리구(處理區)에서 13.65me/100 g 가장 많이 증가(增加)되었고 인산흡수계수(燐酸吸收係數) 5% 조절구(調節區)에서도 9.63me/100g로 증가(增加)되었다. 3. 식물체중(植物體中)의 인산함량(燐酸含量)보다는 $K_2O/Ca+Mg$의 수량(數量)과 더 유의성(有意性)있는 관계(關係)(정상관계(正相關係))를 보였다. 4. 식물체중(植物體中) 인산함량(燐酸含量)과 수량간(收量間)에는 전형적(典型的)인 C-곡선(曲線) 관계(關係)가 관찰(觀察)되어 이 토양(土壤)에서 인산(燐酸)이 일차적(一次的) 수량제한인자(收量制限因子)였음을 나타냈다.