• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.796-803
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• 1998

Intrinsic and proximity gettering are popular processes to get higher cumulative production yield and usually adopt multi-step annealing and high energy ion implantation, respectively. In order to test the combined processed of these, high energy \ulcornerAs\ulcorner ion implantation and 2-step annealing process were adopted. After the ion implantation followed by 2-step annealing, the wafers were cleaved and etched with Wright etchant. The morphology of cross section on samples was inspected by FESEM. The concentration profile of As was measured by SRP. The location and type of secondary defects inspected by HRTEM were dependent on the 1st annealing temperatures. That is, a line of dislocation located at $1.5mutextrm{m}$ apart from the surface at $600^{\circ}C$ lst annealing was changed to some dislocation lines or loops nearby the surface at 100$0^{\circ}C$. The density of dislocation line was reduced but the size of the defects was enlarged as the temperature increased.

• Journal of Chest Surgery
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• 제23권5호
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• pp.854-863
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• 1990

Since the open heart surgery was performed, various kinds of problem concerning the extracorporeal circulation[EGG] have been known. The author investigated the changes of serum potassium ion before and after ECC among the 102 patients including 63 adults and 39 children who underwent open heart surgery from April 19S6 to February 1990 in Chung-Ang University Hospital. The mean values of potassium ion before and after ECC were analyzed according to the influencing factors such as priming solution, aortic cross clamping time, the underlying disease, the type of oxygenator and the amount of cardioplegic solution. The results were as follows: l. In the aspect of congenital and acquired heart disease groups, the mean values of serum potassium ion[Mean\ulcornerS.D.] before and after ECC revealed a significant change only in the acquired heart disease group[congenital; 3.87$\pm$0.48mEq /L vs. 4.05$\pm$0.73mEq /L, P>0.05, acquired: 4.40 $\pm$0.98mEq /L vs. 4.11$\pm$0.52mEq /L, P<0.05]. Between the two groups, the changes of the mean values of serum potassium ion before and after ECC were significant[P<0.05]. But all values were within normal limits. 2. In the aspect of the aortic cross clamping time[ACCT], in the groups of less or more than 120 minutes, the mean values of serum potassium ion before and after ECC revealed no significant change[less than 120 min; 3.97+-0.64mEq /L vs. 3.99+0.67mEq /L, P>0.05, more than 120 min; 4.34+0.82mEq /L vs. 4.27+0.62mEq /L, P>0.05], and The changes of mean values of serum potassium ion between the two groups were not significant[P>0.05]. 3. In both membrane and bubble oxygenator groups, the mean values of serum potassium ion before and after ECC did not reveal a significant difference respectively [membrane; 4.74 +1.40mEq /L vs. 4.28+0.3lmEq /L, P>0.05, bubble; 4.02 +0.60mEq /L vs. 4.05 L0.68mEq/L, P>0.05], and no differences between the membrane and bubble oxygenator groups[P >0.05]. 4. In the groups of membrane and bubble oxygenator in the cases of ACCT more than 120 minutes, the mean values of serum potassium ion before and after ECC did not reveal a significant difference respectively[membrane; 4.36$\pm$0.85mEq /L vs. 4.37$\pm$0.26mEq /L, P>0.05, bubble; 4.30 $\pm$0.80mEq/L vs. 4.23$\pm$0.67mEq/L, P>0.05], and no differences between the two groups[P>0.05]. 5. In spite of increased amount of cold potassium cardioplegic solution, the mean values of serum potassium ion before ECC were similar to those of serum potassium ion after ECC[less than 20ml /kg

• 한국표면공학회지
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• 제39권5호
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• pp.235-239
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• 2006

The aluminum nitride(AlN) layer on Al7075 substrate has been formed through nitrogen ion implantation process. The implantation process was performed under the conditions : 100 keV energy, total ion dose up to $2{\times}10^{18}\;ions/cm^2$. XRD analysis showed that aluminum nitride layers were formed by nitrogen implantation. The formation of Aluminum nitride enhanced surface hardness up to 265HK(0.02 N) from 150HK(0.02 N) for the unimplanted specimen. Micro-Knoop hardness test showed that wear resistance was improved about 2 times for nitrogen implanted specimens above $5\;{\times}\;10^{17}\;ions/cm^2$. The friction coefficient was measured by Ball-on-disc type wear tester and was decreased to 1/3 with increasing total nitrogen ion dose up to $1\;{\times}\;10^{18}ions/cm^2$. The enhancement of mechanical properties was observed to be closely associated with AlN formation. AES analysis showed that the maximum concentration of nitrogen increased as ion dose increased until $5\;{\times}\;10^{17}\;ions/cm^2$.

• 한국안전학회지
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• 제22권3호
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• pp.57-64
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• 2007

Recently, the corrosion of concrete structures has received great attention related with the deterioration of sea-side structures, such as new airport, bridges, and nuclear power plants. In this regards, many studies have been done on the chloride attack in concrete structures. However, those studies were confined mostly to the single deterioration due to chloride only, although actual environment is rather of combined type. The purpose of the present study is, therefore, to explore the influences of carbonation and freezing-thawing action to chloride attack in concrete structures. The test results indicate that the chloride penetration is more pronounced than the case of single chloride attack when the carbonation process is combined with the chloride attack. It is supposed that the chloride ion concentration of carbonation region is higher than the sound region because of the separation of fixed salts. Though the use of fly ash pronounces the chloride ion concentration in surface, amounts of chloride ion penetration into deep region decreases with the use of fly ash. The small reduction of relative dynamic elastic modulus induced from freezing-thawing increases the chloride ion penetration depths much. The present study allows more realistic assessment of durability for such concrete structures which are subjected to combined attacks of both chlorides and carbonation or freezing-thawing but the future studies for combined environment will assure the precise assessment.

• 대한화학회지
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• 제33권4호
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• pp.388-398
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• 1989

기체 감응막전극을 이용하여 수용액 중의 아질산이온을 연속${\cdot}$자동화법으로 정량하는 방법을 개발하였다. 이 방법에서 최종검출기로 쓴 이온선택성 전극은 관형 PVC막 pH 전극이었다. 장치계의 최적조건에서 구한 아질산이온 표준시료에 대한 전극의 감응기울기는 63.5mV/decade 이었으며, 직선감응 범위는 $2.5{\times}10^{-4}\; M{\sim}7.5 {\times} $10^{-2}$M 이었고, 검출한계는 $8.0{\times} 10^{-5}$M이었다. 이 방법은 다른 정량법보다 산성기체종의 방해를 적게 받을 뿐만 아니라 정량에 필요한 시간도 훨씬 단축할 수 있었다.

• 센서학회지
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• 제10권4호
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• pp.259-265
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• 2001

FET형 용존산소 센서는 pH-ISFET를 기본 소자로하여 pH 감지 게이트 근처에 백금으로 된 작업 전극을 형성한 구조를 가지고 있다. 작업전극에 특정한 전위를 인가하면 전기분해로 인하여 용존산소의 농도에 비례하는 수소 이온이 pH 감지 게이트 주변에 발생된다. 따라서 pH-ISFET를 통하여 수소 이온 농도의 변화량을 검출하면 용존산소의 농도를 측정할 수 있게된다. 본 논문에서는 이러한 FET형 용존산소 센서를 어레이 형태로 제작하여 적용하고 측정의 신뢰성을 높이기 위한 알고리즘을 도입한 FET형 용존산소 센서 어레이 측정 시스템을 개발하였다. 또한 상용 용존산소 측정기와 그 성능을 비교 분석하였다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1996년도 춘계학술대회
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• pp.186-186
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• 1996

Streptococcus pneumoniae (pneumococcus), the most common cause of bacterial pneumonia, has an ample polysaccharide(PS) capsule that is highly antigenic and is the source of PS vaccine. This investigation was undertaken to optimize the culture conditions for the production of capsular PS by type 1 pneumococcus. Among several culture media, brain heart infusion (BHI) and Casitone based media were found to support luxuriant growth of pneumococcus type 1 at the same level. Because BHI medium is rather expensive and more complex than the Casitone based media, the Casitone based media was used to study optimization of the culture condition. The phase of growth which accomodated maximum PS production was logarithmic phase. Concentrations of glucose greater than 0.2% did not enhance growth or PS production. Substitution of nitrogen sources with other resources or supplemention of various concentrations of metal ion (with the exception of calcium ion) had adverse effects on growth and PS production. On the other hand, low level aeration was beneficial for increased PS production. Addition of 3 mg/I concentration of methionine, phenylalanine, and threonine were found to enhance growth and PS production. The synergistic effect of all the favorable conditions observed in pneumococcal growth assays provided a two-fold cumulative increase in capsular PS production.

• Bulletin of the Korean Chemical Society
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• 제24권9호
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• pp.1245-1250
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• 2003

Pseudo-first-order rate constants ($k_{obs}$) have been measured spectrophotometrically for the reactions of 4-nitrophenyl benzoate with a series of pyridines in $H_2O$ containing 20 mol % DMSO. The plots of kobs vs pyridine concentration are linear up to ca. 0.1 M pyridines, indicating that the effect of self-association of pyridines with their conjugate acids are insignificant in this concentration range. The Bronsted-type plot has been obtained to be linear with a ${\beta}_{nuc}$ value 1.11, suggesting that the pyridinolyses proceed through a rate-determining breakdown of the zwiterionic addition intermediate. The pyridines studied have shown higher reactivity than isobasic primary and secondary amines toward the substrate. 1-Benzoyl-4-dimethylaminopyridinium ion, a possible intermediate, has not been detected since the rate of its hydrolysis in the reaction condition is comparable with or even faster than its formation.

• 한국화재소방학회논문지
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• 제34권1호
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• pp.66-71
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• 2020

리튬-이온 배터리를 폐기하는 방법으로 흔히 사용되고 있는 염수를 이용한 방전 방법은 자칫 화재로 이어질 개연성이 있음에도 불구하고 배터리의 염수 방전 과정의 화재 위험성에 대한 연구는 많지 않다. 본 연구에서는 리튬-이온 배터리 중 휴대폰 배터리를 대상으로 하여 염수에 배터리를 담가 방전 시킬 때 방전특성과 발열에 의한 화재 발생 가능성을 확인하고자 염수농도와 배터리의 개수를 변화시킨 여러 조건에서 실험을 수행하였다. 각 조건에서 방전전압 및 배터리의 발열온도를 측정하여 방전 과정 및 발열에 의한 화재 위험성을 예측하였다. 실험 결과로는, 염수농도가 높을수록 휴대폰 배터리의 방전이 더 잘 되었으며, 발열온도 또한 높게 측정 되었고, 염수에 침수된 배터리 1개의 발열온도보다 중첩된 배터리의 발열온도가 더 높게 측정되었다. 또한, 배터리의 가장 높은 발열이 발생하는 부분은 (+),(-)전극에서 발생하는 것을 알 수 있었다.

• 대한토목학회논문집
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• 제29권4A호
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• pp.347-353
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• 2009

콘크리트 내의 염소이온 침투에 영향을 미치는 정성적인 주요 인자로는 물-결합재비, 시멘트 종류, 재령, 주위 환경의 염소이온 농도 및 건습조건 등이 있다. 이에 따라 이 연구에서는 염소이온 확산실험을 통해 시멘트 종류 및 환경조건이 염소이온 확산특성에 미치는 영향을 조사하였다. 이를 위하여 물-결합재비 32%, 38% 및 43%에 대해서 보통 포틀랜드 시멘트(OPC), 2성분계 시멘트(BBC) 및 3성분계 시멘트(TBC) 각각을 사용한 콘크리트의 확산계수를 측정하였으며, 또한 물-결합재비 43%에 대해서 표준양생 및 해양환경에 폭로된 콘크리트의 확산계수를 측정하였다. 그 결과, 염소이온 침투 저항성은 물-결합재비가 감소함에 따라 증가하고, 2성분계 및 3성분계 시멘트를 사용한 콘크리트의 침투 저항성이 OPC 콘크리트에 비하여 우수한 것으로 나타났다. 따라서, 염해환경에 노출된 철근콘크리트 구조물의 내구수명을 증진시키기 위하여 광물질 혼화재를 혼입한 2성분계 혹은 3성분계 시멘트의 사용이 요구된다. 한편, 현장 폭로 시편의 염소이온 침투 저항성은 일정하지 않은 대기온도 하에서 염소이온의 침투, 파랑 및 건습반복의 영향으로 표준양생 시편의 경우보다 다소 저하되는 것으로 나타났다.