• 한국균학회지
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• 제17권3호
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• pp.149-153
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• 1989

내산성 ${\alpha}$-아밀라제를 강력히 생산하는 Aspergillus niger K-25 균주를 토양으로부터 분리하였다. 내산성 아밀라제 효소를 생산하기 위한 균주의 배양조건을 조사하였다. 합성배지 A(soluble starch 3.5%, peptone 2%, $KH_2PO_4$ 0.5%, $MaSO_4{\cdot}7H_2O$ 0.25%, $FeCI_3$ 1.0%, pH 6)에서 배양시 아밀라제 생산이 높았다. 밀기울에 fumaric acid 완충용액(pH3)을 1 : 1(W/V)로 첨가하여 배양했을 때 내산성 ${\alpha}$-아밀라제의 생산력은 완충액 HCI, citric acid과 밀기울만 넣은 배지보다 약 2배가 높았고, 배지 A보다 현저하게 높았다.

• 대한화학회지
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• 제54권3호
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• pp.275-282
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• 2010

분자 내 수소결합 가능성을 가지고 있는 2-fluorocyclopropanemethanol과 2-chlorocyclopropanemethanol에 대하여 MP2/6-311++G(d,p) 방법과 B3LYP/6-311++G(d,p) 방법으로 최적화 계산을 수행하였다. 두 분자 모두 가장 안정한 conformer에서 O-H의 수소가 F나 Cl을 향하고 있어 수소결합 가능성을 보이기는 하나 $H{\cdots}F$, $H{\cdots}Cl$ 거리가 van der Waals radii보다 커서 강한 수소결합이라 보기 힘들고 두 번째 안정한 conformer의 경우가 가까운 $H{\cdots}F$, $H{\cdots}Cl$ 거리를 보이며 더 강한 수소결합 가능성을 보였다. 그러나 에너지가 5 ~ 7 kJ 더 높게 나타났다. Methanol group과 F나 Cl이 서로 반대 방향을 향할 때 일반적으로 안정하나 앞의 가장 안정한 conformer보다는 에너지가 높다.

• 대한수학회보
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• 제53권1호
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• pp.153-161
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• 2016

It is shown that the algebra $\mathfrak{H}^{\infty}$ of bounded Dirichlet series is not a coherent ring, and has infinite Bass stable rank. As corollaries of the latter result, it is derived that $\mathfrak{H}^{\infty}$ has infinite topological stable rank and infinite Krull dimension.

• 대한수학회논문집
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• 제15권1호
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• pp.123-131
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• 2000

Let {X(t) : t $\geq$B 0} be a Symmetric $\alpha$ Stable and H-Self-similar process with stationary increments. We examine a.s. Holder unboundedness of S$\alpha$S H-sssi Chentsov processes and H-sssi Chentsov fields for order ${\gamma}$>H. Finally, we prove a.s. Holder continuity of S$\alpha$S H-sssi processes with ergodic seating transformations for the case of H>1/$\alpha$.

• Journal of Microbiology and Biotechnology
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• 제11권4호
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• pp.558-563
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• 2001

A new alkalophilic strain of Bacillus pumilus JB¬05 producing bleach-stable and halo-tolerant alkaline protease was isolated from cement industry effluents in Karnataka, India. The effects of carbon and nitrogen sources on protease production by this alkalophilic strain were observed after a 30-h incubation. A high level of alkaline protease activity was obtained in the presence of starch as the carbon and peptone as the nitrogen sources. The partially purified enzyme showed an optimum temperature and pH activity at $58^{\circ}C$ and 10.5, respectively. The enzyme was completely inhibited by PMSF (95.0%) indicating it as a serine protease. It is bleach-stable as it retained 35% original activity in the presence of 10% (v/v) hydrogen peroxide at $30^{\circ}$C after 2 h and is halo-tolerant as it retained 70% original activity in the presence of 2.5 M sodium chloride at $30^{\circ}C$ after 2 h incubation.

• 한국물환경학회지
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• 제27권4호
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• pp.438-444
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• 2011

Magnesium is one of the abundant natural resources in the earth crust and seawater, which is directly related to various organisms activities interconnecting with water-rock system. In aqueous system, magnesium is known to predominantly exist in the form of $Mg^{2+}$ ion which is verified in its $E_h-pH$ diagram. When it is at equilibrium in aqueous system, temperature takes an essential role to complete equilibrium states. This study represents the change of the stable region of magnesium ion according to temperature, and how the consequences would affect aquatic organisms. It was revealed that there is a noticeable tendency shrinking the stable region of magnesium ion in a diagram as temperature increases, and as a result, aquatic bio-species presumably have difficulties to absorb the nutrient. Also, it was considered that the water system would be acidified by decreasing alkalinity.

• 대한환경공학회지
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• 제38권5호
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• pp.228-235
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• 2016

아질산화 반응을 통한 nitrite 축적은 단축질소제거 혹은 anammox 공정 수립을 위해 필수적이고 이 반응의 속도가 전체 질소제거공정의 효율에 큰 영향을 미칠 수 있다. 본 연구는 부유 미생물 연속류 반응기에서 pH 농도가 암모니아 폐수(2,000 mgN/L) 처리에 주는 복잡하고 다양한 영향 들을 modeling과 실험을 통해 종합적으로 분석하였다. modeling 연구 결과 반응의 안정성(stability)은 pH에 의해 지대한 영향을 받으며, free ammonia 저해가 심해지는 알칼리성 환경일수록 안정적 운전 영역(stable region)은 축소되었다. 기질과 pH의 좌표 상에서 stable region과 unstable region을 가르는 경계(stability ridge) 근처에서 안정적인 최대반응속도를 얻을 수 있고, 이 운전조건에서 아질산 축적 가능성도 최대가 되었다. stability ridge 근처의 조건에서 반응기를 운전한 결과 아질산화속도는 안정적으로 약 $6kgN/m^3-d$까지 얻을 수 있었고, 아질산축적율은 약 99% 이었다. 그러나 unstable region에서는 부하증가를 통한 반복된 교란 결과 유출수 암모니아 농도가 회복 불가능한 상태로 상승하였다. Modeling 결과 고유(intrinsic) 최적 pH 값을 고정하여도 실험에서 관찰되는 최적 운전 pH는 사용 기질의 농도가 높을수록 낮아지는 것으로 나타났으며, 이는 문헌에서 보고된 경향과 일치 하였다. 본 연구의 modeling 조건에서 95% 아질산화(5%는 암모니아로 잔존)를 위한 최적 운전 pH는 ~8.0인 것으로 예측되었으나, anammox 유입수 생산을 위해 55% 아질산화하려 할 때의 최적 운전 pH는 ~7.2로 낮아 졌다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.359-360
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• 2009

• 대한미생물학회지
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• 제20권1호
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• pp.55-63
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• 1985

Phosphate, ammonia, glucosamine, glucose, pyruvate, succinate, fumarate, malate and acetate were examined for their ability to control the heat-stable enterotoxin (ST) production in succinate salts medium or in M9 medium. The results obtained were summerized as follows. 1. When the initial phosphate concentration was adjusted to 1.0mM, ST production was decreased to 80u/ml or less. But when the initial phosphate concentration was adjusted to 64mM or 100mM, enterotoxin production was 320u/ml. 2. When the initial ammonia concentration in the medium was adjusted to 1.0mM, no ST production and cell growth were observed. But when ammonia concentration was adjusted to 10mM, 19mM, 38mM or 76mM, enterotoxin production was 320u/ml. 3. Among carbon sources, glucosamine, glucose, pyruvate, succinate, fumarate, malate and acetate, acetate supported the highest specific production (928 unit/O.D.) of heat-stable enterotoxin. From this results, we could assume that heat-stable enterotoxin production is controlled by stringent control mechanism. 4. When the pH of the succinate salts medium was kept between 6.2 to 6.5, no heat-stable enterotoxin production was observed, but when the pH of the medium was kept between pH 6.2 to 6.5, 267 unit/O.D. of heat-stable enterotoxin was produced. 5. Glucose inhibited the heat-stable enterotoxin production and the mechanism was assumed due to its capacity to lower the pH of the medium during catabolysis and its high metabolic energy.

• 한국동물위생학회지
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• 제42권4호
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• pp.265-274
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• 2019

Delayed arrival of blood samples from the field and a large number of samples delivered often causes delay in sample analysis leading to inaccurate measurements. Therefore, this study aimed to assess whether prolonged storage in refrigerator could influence the stability of cattle blood samples and to establish an optimal time limit for complete blood count (CBC) parameters and blood gas and electrolyte (BGE) parameters analyses. Samples collected from healthy cows were tested immediately for CBC and BGE using automated hematology, blood gas and electrolyte analyzers. Samples were kept in refrigerator at 4℃ and analyzed after 6 h, 12 h, 24 h, 48 h, 72 h, 120 h, and 192 h of storage. Mean differences between observations were assessed at 5% significance level using ANOVA and Duncan's multiple range test. Total CBC parameters and the platelet profile remained stable for 192 h, except for MCHC. Among leukocyte-related counts, NEU and EOS remained stable for 192 hours. WBC and LYM, and MONO values produced inconsistent measurements which recovered its initial measurement after 12 h and 24 h of storage, respectively, then remained stable until 120 h. Among the blood gas indices, PCO₂, PO₂, tCO₂, and BE showed declining and significant changes over time, but pH, tHb, and SO₂ remained stable for 192 h. Electrolyte status in the blood showed that ions are unstable and tend to change in as early as 6 h of storage. This study established that cattle blood specimens for CBC analysis can be stored for 120 h at 4℃, but specimens for BGE analyses must be tested within 6 to 24 h.