• 전기화학회지
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• 제4권4호
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• pp.146-151
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• 2001

위상이동 방법을 이용하여 다결정 Ni|0.05M KOH수용액 계면에서 음극 $H_2$발생 반응을 위한 과전위 전착(흡착)된 수소의 Frumkin 흡착등온식을 연구조사 하였다. 다결정 Ni|0.05M KOH수용액 계면에서, 최적중간주파수일 때 위상이동$(0^{\circ}\leq{\phi}\leq90^{\circ})$ 거동은 표면피복율 $(1\geq{\theta}\geq0)$ 거동에 정확하게 상응한다. 최적중간주파수일 때 위상이동 변화 $(-{\phi}\;vs.\;E)$즉 위상이동 방법은 다결정 Ni|0.05M KOH수용액 계면에서 음극 $H_2$발생 반응을 위한 과전위 전착(흡착)된 수소의 Frumkin흡착등온식$(\theta\;vs.\;E)$을 추정할 수 있는 새로운 방법으로 사용될 수 있다. 다결정 Ni|0.05M KOH 수용액 계면에서, 표면피복율에 따른 과전위 전착(흡착)된 수소의 표준자유에너지 변화율(r), Frumkin 흡착등온식의 상호작용 파라미터(g), 표면피복율$(\theta)$에 따른 과전위 전착(흡착)된 수소의 흡착평형상수(K)와 표준자유에너지$({\Delta}G_{\theta})$는 각각 $24.8kJ mol^{-1},\;10,\;5.9\times10^{-6}{\leq}K{\leq}0.13,\;and\;5.1\leq{\Delta}G_{\theta}\leq29.8kJ\;mol^{-1}$이다. 전극속도론적 파라미터$(r,\;g,\;K,\;{\Delta}G_{\theta})$는 표면피복율${\theta}에 따른다.

• 대한미생물학회지
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• 제34권6호
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• pp.533-542
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• 1999

H. pylori produces urease abundantly amounting to 6% of total protein of bacterial mass. Urease genes are composed of a cluster of 9 genes of ureC, ureD, ureA, ureB, ureI, ureE, ureF, ureG, ureH. Production of H. pylori urease in E. coli was studied with genetic cotransformation. Structural genes ureA and ureB produce urease apoprotein in E. coli but the apoprotein has no enzymatic activity. ureC and ureD do not affect urease production nor enzyme activity ureF, ureG, and ureH are essential to produce the catalytically active H. pylori urease of structural genes (ureA and ureB) in E.coli. The kinetics of activation of H. pylori urease apoprotein were examined to understand the production of active H. pylori urease. Activation of H. pylori urease apoprotein, pH dependency, reversibility of $CO_2$ binding, irreversibility of $CO_2$ and $Ni^{2+}$ incorporation, and $CO_2$ dependency of initial rate of urease activity have been observed in vitro. The intrinsic reactivity (ko) for carbamylation of urease apoprotein co expressed with accessory genes was 17-fold greater than that of urease apoprotein expressed without accessory genes. It is concluded that accessory genes function in maximizing the carbamylating deprotonated ${\varepsilon}$-amino group of Lys 219 of urease B subunit and metallocenter of urease apoprotein is supposed to be assembled by reaction of a deprotonated protein side chain with an activating $CO_2$ molecule to generate ligands that facilitate productive nickel binding.

• Applied Biological Chemistry
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• 제20권3호
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• pp.300-309
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• 1977

The information related to the heavy metal pollution in the environment was obtained from studies on the effects of pH, phosphate and soil properties on the adsorption of metal ions (Cd, Cu, Ni, and Zn) by soils. Three soil materials; soil 1 with low CEC (8.2 me/100g) and low organic carbon content (0.34%); soil 2 with high CEC (36.4 me/100g) and low organic carbon content (1.8%) and soil 3 with high CEC (49.9 me/100g) and high organic carbon content (14.7%) were used. Soils were adjusted to several pH's and equilibrated with metal ion mixtures of 4 different concentrations, each having equal equivalents of each metal ion (0.63, 1.88, 3.12 and 4.38 micromoles per one gram soil with and without 10 micromoles of phosphate per one gram soil). Reported here are the results of the equilibrium study on soil I. The rest of the results on soil 2 and soil 3 will be repoted subsequeutly. Generally higher metal ion concentration solution resulted in higher final metal ion concentrations in the equilibrated solution and phosphate had minimal effect except it tended to enhance removal of cadmium and zinc from equilibrated solutions while it tended to decrease the removal of copper and nickel. In soil 1, percentages of added metal ions removed at pH 5.10 were; Cu 97, Ni 69, Cd 63, and Zn 55, while increasing pH to 6.40, they were increased to Cu 90.9, Zn 99, Ni 96, and Cd 92 per As initial metal ion concentration increased, final metal ion concentrations in the equilibrated solution showed a relationship with pH of the system as they fit to the equation $p[M^{++}]=a$ pH+b where $p[M^{++}]=-log$[metal ion concentration in Mol/liter]. The magnitude of pH and soil effects were reflected in slope (a) of the equation, and were different among metal ions and soils. Slopes (a) for metal ions in the aqueous system are all 2. In soil 1 they were; Zn 1.23, Cu 0.99, Ni 0.69 and Cd 0.59 at highest concentration. The adsorption of Cd, Ni, and Zn in soil 1 could be represented by the Iangmuir isotherm. However, construction of the Iangmuir isotherm required the correction for pH differences.

• 대한화학회지
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• 제33권4호
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• pp.366-370
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• 1989

새로운 거대고리 리간드 1,15,18-triaza-3,4 : 12,13-dibenzo-5,8,11-trioxa-cycloeicosane(NdienOdien$H_4$=$N_3O_3$)를 합성하여 $25^{\circ}C$ 95% 메탄올 용액에서 전위차계를 이용하여 양성자 첨가반응의 평형상수를 구한 결과 log $K_1$ ; log $K_2$ ; log $K_3$는 9.1; 8.1; 3.6이었다. 또한 위의 리간드와 이미 합성된 리간드 1,12,15-triaza-3,4;9,10-dibenzo-5,8-dioxa-cycloheptadecane(NdienOen$H_4$=$N_3O_2$)를 각각 Ni(II), Cu(II)의 금속이온과의 착물을 합성하여 수용액에서 산을 가해 착물의 산해리반응 속도 상수를 여러온도에서 분광광도법으로 측정하였다. 또한 활성화에너지($E_a$)와 활성화파라메타 ${\Delta}H^{\neq}$, ${\Delta}S^{\neq}$를 구하였다. 그리고 이들의 자료로부터 이 반응계의 타당한 해리메카니즘을 제안하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.72-72
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• 2012

Lithium rechargeable batteries have been widely used as key power sources for portable devices for the last couple of decades. Their high energy density and power have allowed the proliferation of ever more complex portable devices such as cellular phones, laptops and PDA's. For larger scale applications, such as batteries in plug-in hybrid electric vehicles (PHEV) or power tools, higher standards of the battery, especially in term of the rate (power) capability and energy density, are required. In PHEV, the materials in the rechargeable battery must be able to charge and discharge (power capability) with sufficient speed to take advantage of regenerative braking and give the desirable power to accelerate the car. The driving mileage of the electric car is simply a function of the energy density of the batteries. Since the successful launch of recent Ni-MH (Nickel Metal Hydride)-based HEVs (Hybrid Electric Vehicles) in the market, there has been intense demand for the high power-capable Li battery with higher energy density and reduced cost to make HEV vehicles more efficient and reduce emissions. However, current Li rechargeable battery technology has to improve significantly to meet the requirements for HEV applications not to mention PHEV. In an effort to design and develop an advanced electrode material with high power and energy for Li rechargeable batteries, we approached to this in two different length scales - Atomic and Nano engineering of materials. In the atomic design of electrode materials, we have combined theoretical investigation using ab initio calculations with experimental realization. Based on fundamental understanding on Li diffusion, polaronic conduction, operating potential, electronic structure and atomic bonding nature of electrode materials by theoretical calculations, we could identify and define the problems of existing electrode materials, suggest possible strategy and experimentally improve the electrochemical property. This approach often leads to a design of completely new compounds with new crystal structures. In this seminar, I will talk about two examples of electrode material study under this approach; $LiNi_{0.5}Mn_{0.5}O_2$ based layered materials and olivine based multi-component systems. In the other scale of approach; nano engineering; the morphology of electrode materials are controlled in nano scales to explore new electrochemical properties arising from the limited length scales and nano scale electrode architecture. Power, energy and cycle stability are demonstrated to be sensitively affected by electrode architecture in nano scales. This part of story will be only given summarized in the talk.

• 한국환경보건학회지
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• 제44권1호
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• pp.55-62
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• 2018

Objectives: This study set out to measure the heavy metal concentrations in waste water produced in the casting pickling process at dental technical laboratories and examine the actual state of its treatment. Methods:The investigator measured the concentrations of each heavy metal at 55 dental technical laboratories using an inductively coupled plasma optical emission system. Results: The annual usage of electrolytes was under 10 L in 50 (90.9%), and was 10L or more in five (9.1%) laboratories. Among the laboratories, 15 (27.3%) commissioned the treatment of waste,12 (21.8%) treated the waste with general sewage,and 28 (50.9%) treated the waste in aseptic tank. The arithmetic $mean{\pm}standard$ deviation and the geometric mean of chrome(Cr) were $75.3{\pm}50.9$ and 58.3 mg/L; those of cobalt (Co) were $112.3{\pm}106.7$ and 66.1 mg/L; those of nickel (Ni) were $62.9{\pm}83.5$ and 8.9 mg/L; those of molybdenum (Mo) were $17.1{\pm}13.4$ and 12.0 mg/L; those of iron (Fe) were $31.5{\pm}44.1$ and 6.2 mg/L; those of lead (Pb) were $0.3{\pm}0.3$ and 0.3 mg/L; those of beryllium (Be) were $3.6{\pm}3.6$ and 2.0 mg/L. The hydrogen ion concentration was under pH 2 across all the samples. Conclusions: The findings show that the dental technical laboratories were not doing well with the separation, storage, collection, and treatment of the electrolytes they discarded, and that most of the electrolytes were introduced through the general sewage or aseptic tank. The causes of this include alack of perception among the practitioners at dental technical laboratories and contracted companies avoiding collection for economic reasons. There is a need for education to improve the perceptions of waste water treatment among the practitioners at dental technical laboratories. Environment-related departments should be stricter with legal applications in the central and local governments. It is also required to provide proper management of commissioned treatment.

• 한국지하수토양환경학회지:지하수토양환경
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• 제9권4호
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• pp.15-23
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• 2004

제설제를 살포하는 것은 도시지역에서 자동차가 겨울철에 운행하는 동안 안전한 운전을 가능하게 한다. 하지만 많은 양의 제설제 (염화칼슘과 소금)를 사용하는 것은 심각한 환경문제를 발생시키고 도로변 퇴적물에 함유된 중금속의 거동을 변화시키게 되며, 결과적으로 염소이온과의 착이온형성에 기인된 중금속의 이동성을 증가시키게 될 것이다. 제설제의 농도가 중금속 (카드뮴, 아연, 구리, 납, 비소, 니켈, 크롬, 코발트, 망간 및 철)의 용출특성과 이동성에 미치는 영향을 연구하기 위하여, 서울시 주요 도로변에서 채취한 퇴적물을 대상으로 제설제의 농도 (0.01-5.0M)를 변화시켜 용출실험을 수행하였다. 연구결과, 도로변 퇴적물에 함유된 아연, 구리 및 망간은 쉽게 용해되어 이동되는 반면, 크롬과 코발트는 도로변 퇴적물에 강하게 고정되어 있음을 관찰하였다. 이번 용출실험에서 검출된 아연 (최대 $118.6{\mu}g/g$). 구리 (최대 $44.9{\mu}g/g$) 및 망간 (최대 $42.2{\mu}g/g$)의 함량은 상대적으로 높은 함량이었다. 제설제는 흡착 (또는 침전)된 금속과 용해된 금속 사이의 분배를 감소시키며, 이는 제설제가 용해된 눈 녹은 물에 용존 중금속 함량을 증가시키게 되어 결과적으로 지표수의 수질을 악화시키게 된다. 또한, 도로에 제설제를 살포하는 것에 의해 중금속이 지하수까지 침투되어 지하수를 오염시키게 될 것이다.

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.257-268
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• 1998

During cleaning and shaping of narrow and curved canals, it is very difficult or nearly impossible to maintain the original canal shape. Procedural accidents such as, ledge, zipping, perforation, and instrument breakage are frequently occurred and even may lead to failure of endodontic therapy. To prevent these kinds of accidents, various instrumentation techniques and materials have been introduced. Recently some nickel titanium (NiTi) files are introduced and it is reported that These NiTi files created rounder preparations with less transportation than conventional instruments in curved canals. This study compared the change of the canal curvature and procedural accidents after instrumentation produced by stainless steel K-flexo file, and NiTi rotary files (Profile 29 and Quantec 2000). Thirty narrow and curved canals (25-45 degree) of extracted human molars were randomly divided into three groups. In group 1, canals were instrumented using a step-back and watch-winding/pull motion with K-flexo files. In group 2, canals were prepared with Profile 29. Group 3, canals were prepared with Quantec 2000 files. Before and after preparation of canals, periapical radiographs were taken and scanned. The change of canal curvature were measured using Photoshop 4.0 program and the incidence of procedural accidents were also evaluated. The results were as follows: 1. All group showed some loss of canal curvature after instrumentation. 2. Average loss of canal curvature was $6.70{\pm}5.31$ degree for group 1, $3.80{\pm}2.57$ degree for group 2, and $5.40{\pm}4.83$ degree for group 3. All group There was significant change in curvature between before and after instrumentation (p<0.05). But there was no statistical difference amoung 3 groups. 3. In group I, there were no procedural accidents, such as ledging, perforation, or instrument fracture. In group 2, two cases of ledge and one case of instrument fracture were produced Goup 3, each one case of ledge, perforation and instrument fracture were occurred. Whthin the limits of above results, It seems that NiTi rotary instrumentation is not All Mighty and if we use uncarefully, it is more dangerous to produce some procedural accidents than conventional hand files. But more studies should be taken to evaluate the exact effects of NiTi rotary instrumentations.

• 한국환경생태학회지
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• 제30권1호
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• pp.19-38
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• 2016

본 연구는 안동 사문암지대의 관속식물상, 현존식생 및 토양특성에 대한 조사를 수행하였다. 2014년 4월부터 10월까지 총 7회에 걸쳐 현지조사를 실시한 결과 관속식물은 88과 239속 311종 6아종 33변종 6품종 3교잡종으로 총 359분류군이 확인되었으며, 본 연구에서 249분류군의 분포가 새로이 밝혀졌다. 안동 사문암지역은 식물구계학상 온대중부지역에 속하고 낙엽활엽수와 침엽수의 혼합림으로 구성된다. 한반도 고유종은 외대으아리, 은사시나무, 오동나무, 벌개미취가 확인되었다. IUCN 평가기준에 따른 적색목록식물은 7분류군으로 준위협종(NT)에 채고추나물, 원지, 쑥방망이, 관심대상종(LC)에 낙지다리, 솜양지꽃, 창포, 미평가종(NE)으로 멱쇠채가 조사되었다. 식물구계학적 특정식물은 IV등급 2분류군, III등급 5분류군, II등급 4분류군, I등급 7분류군 등 19분류군이 발견되었다. 귀화식물은 34분류군으로 확인되었으며, 귀화율 9.5%, 도시화지수 10.6%로 나타났다. 연구지역의 산림토양은 표층~20cm에서 양토와 미사질양토, 20cm~40cm에서 양토와 미사질점토인 것으로 분석되었다. 토양 내 중금속은 Ni과 Cd의 함량이 높은 것으로 나타났다.

• 감성과학
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• 제21권3호
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• pp.141-150
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• 2018

본 연구의 목적은 첫째 마찰 시 직물의 면적을 증가시켜 에너지 수확의 효율을 높일 수 있는 입체 자수 기법 및 전도성 직물 재료를 탐색하고, 둘째 높은 효율을 보이는 입체 자수 기법을 토대로 브러싱 가공을 실시하여 가공 후의 발생 전압을 분석하며, 셋째 이를 근거로 마찰 에너지 수확 증대형 직물의 구조를 탐색하는 것이다. 이를 위해 다음의 두 가지 실험을 실시하였다. "실험 I"에서는 인체로부터 마찰 에너지를 수확하는 효율에 영향을 미치는 직물 내 주요 변인으로, 1) 입체 자수 기법(사틴 기법, 파일 기법), 2) 전도성 직물 재료(구리 기반 MPF, 니켈 기반 MPF)를 선정하고, 이 두 변인들의 조합에 따른 4개의 시료를 제작하여 마찰 시 발생 전압의 차이를 비교 분석하였다. "실험 II"에서는 높은 효율을 보이는 입체 자수 방식의 시료를 대상으로 브러싱 가공을 실시하여 가공 후의 발생 전압을 분석하였다. 그 결과, 두 전도성 직물 재료 모두에 있어서 파일 자수 직물 구조가 사틴 자수 직물 구조에 비해 높은 마찰 에너지 수확 효율을 보였고, 이러한 결과는 마찰 면적에 따른 전하 밀도와 발생 전압이 비례하는 마찰 에너지 수확의 원리와 일치하였다. 이를 통해 마찰 면적이 큰 파일 자수 직물 구조가 마찰 면적이 상대적으로 작은 사틴 자수 직물 구조에 비해 에너지 수확 효율을 증대시키는데 유리한 방식임을 알 수 있었다. 또한 브러싱 가공 후의 에너지 수확 효율도 마찰 면적 증대로 인해 가공 전에 비해 높게 나타나, 브러싱 가공 방식이 마찰 에너지 수확 증대에 있어서 유리한 가공 방식임을 알 수 있었다.