• 자원리싸이클링
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• 제16권4호
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• pp.33-39
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• 2007

직류 ESR(Electro Slag Remelting)장치를 이용하여 타이타늄 스크랩의 재용해 및 정련에 관한 기초연구를 수행하였다. 비소모성 양극으로는 흑연봉을, 슬래그로는 $CaF_2-TiO_2$계를 사용하였다. 재용해한 타이타늄 잉곳의 형상 및 산소 함량에 미치는 슬래그 조성의 영향을 검토하였다. $CaF_2-TiO_2$계 슬래그에서는 잉곳 내부에 슬래그의 혼입이 없는 매우 양호한 형상의 타이타늄 잉곳이 형성되었으며, 산소 함량도 타이타늄스크랩보다 낮은 값을 나타내었다. $CaF_2-TiO_2$계 슬래그에 CaO를 첨가한 경우 잉곳 내부에 슬래그가 혼입되었으며, 산소 농도도 Ti 스크랩 보다 높은 값을 나타내었다.

• The Korean Journal of Physiology
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• 제16권2호
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• pp.119-128
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• 1982

The frog truncus arterious were studied with conventional glass microelectrode technique in order to elucidate the underlying mechanism of spontaneous pacemaker activity. The analyses were focussed on the ionic nature of pacemaker current by changing the concentrations of extracellular $K^+$ and, $Na^+$, or by using blockers of K- and Ca-current and chronotropic transmitters. 1) The action potential of the spontaneously active truncus arteriosus has some characteristic feature of maximal distolic potential ranged from -65 to -75 mV, resting potential from -45 to -50 mV and overshoot voltage about +30 mV, respectively. Duration of the action potential taken from rapid upstroke to maximal diastolic potential was about 600 msec. Usual discharge rate was $25{\sim}30/min$ at room temperature $(18{\sim}20^{\circ}C)$. 2) The sensitivity of the resting membrane potential to change extracellular potassium concentrations $(0{\sim}12\;mM)$ was relatively low. Transient hyperpolarization was appeared in the 12 mM K Ringer after 10 min exposure to 0 mM K and it could be related to Na-pump reactivation by high potassium. 3) Reduction of extracellular sodium concetrations diminished the amplitude and frequency of the action potential. In Ringer solution containing 30% Na (substituted by equimolar Tris), spontaneous activity stopped but reappeared as very slow and small action potential. There was no spotaneous activity in zero Na Ringer solution. 4) Caesium(10 mM), K-current blocker decreased the frequency of the action potential and also pacemaker depolarization. Manganese (2 mM) known to be Ca-current antagonist, blocked spontaneous activity completely. 5) Adrenaline and acetylcholine had no chronotropic effect. But adrenaline increased the duration of plateau phase and the magnitude of the action potential in the follower cell. It is concluded that K-, Na-and Ca-current components are involved in the genesis of spontaneous activity of the frog truncus arteriosus like cardiac pacemaker tissues. But the insensitivity of truncus arteriosus to adrenaline and acetylcholine indicates that there are some different control mechanisms of spontaneous rhythm in two tissues.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.697-700
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• 2001

In this paper, the structural and electrical properties of the Sr$_{1-x}$ Ca$_{x}$TiO$_3$ (0$\leq$x$\leq$0.2) (0$\leq$r$\leq$0.2)-based grain boundary layer ceramics were investigated by X-ray, SEM and V-I system. Increasing the Ca content, the average grain size and the lattice constant were decreased. The relative density of all specimens was >96%. The 2nd phase formed by thermal diffusing from the surface lead to a very excellent electrical properties, that is, $\varepsilon$$_{r}$>50000, tan$\delta$<0.05, $\Delta$C< $\pm$ 10%.\pm$ 10%.%.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1998년도 학술발표회
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• pp.37-37
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• 1998

Effects of endothelin-l (ET-l) on contraction, $Ca^{2＋}$ transient and L -type $Ca^{2＋}$ current ( $I_{Ca,L}$) were investigated in single ventricular myocytes isolated from guinea-pig hearts. ET-l at concentrations of 5 and 10 nM produced a biphasic pattern of inotropism： a first decrease in contraction by 34.4$\pm$2.5 ％ of the control followed by a sustained increase in contraction by 66.6$\pm$8.4% (mean$\pm$S.E.M., n=9).(omitted)

• The Korean Journal of Physiology
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• 제23권2호
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• pp.301-312
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• 1989

It well known that the magnitude of contraction and the shape of action potential depend upon the stimulation frequency and the duration of resting period (positive and negative staircase). Although the underlying mechanism of the staircase phenomenon is not fully understood, it has been suggested that staircase could be related to the intracllular $Ca^{2+}$ concentration. In order to elucidate the role of intracellular $Ca^{2+}$ on the contraction and action potential staircases, we examined the effects of 1 mM 4-aminopyridine (4-AP), 0.5 uM verapamil, 1 uM ryanodine, or reduction of extracellular Na concentration to 30% $(substituted\;by\;equimolar\;Li^+)$ in small atrial strips of the rabbit $(3{\times}10\;mm)$. The results obitained were as follows; 1) When the stimulation frequency was increased from 0.1 Hz to 2 Hz, positive staircase of the contraction and elevation of plateau level in action potential were found in control and the conditions of Na reduction and treatments of 4-AP, verapamil and ryanodine. 2) When stimulation frequency returned to 0.1 Hz from 1 min rest just after 2 Hz stimulation fer 1 min, the magnitudes of initial few contractions were larger than that of steady state contraction (post-rest potentiation) except, ryanodine or Na-reduction groups. 3) Negative staircase of contraction was developed in control and 4-AP group at post-rest 0.1 Hz stimulation and the plateau level of the action potential was decreased at the same time. But the reduction of contraction or the plateau level was much smaller in 4-AP group and than in control. From the above results it can be concluded that contraction and action potential staircase is dependent upon transmembrane $Ca^{2+}-current\;and\;Ca^{2+}$release from the SR.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.54-54
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• 2003

Prostate gland contains neuroendocrine cells (PNECs) are playing important roles in physiological and pathophysiological processes of the prostate gland. Here, we investigated the role of purinoceptors in PNECs freshly isolated from rat ventral prostate (RPNECs) that show immunoreactivity to chromogranin A. Fura-2 ratiometry revealed that ATP evokes both fast Ca$\^$2+/ influx and store Ca$\^$2+/ release in RPNECs. A whole-cell patch clamp study demonstrated fast inactivating cationic current activated by ATP or by ${\alpha}$,${\beta}$-MeATP, which was blocked by ATP-TNP. The activation of P2X inward current was tightly associated with a sharp increase in [Ca$\^$2+/]$\sub$c/. The presence of P2X1/3 subtypes were proved by RT-PCR analysis. For the stored Ca$\^$2+/ release, ATP and UTP showed similar effects, suggesting the dominant role or P2Y2 subtypes, also confirmed by RT-PCR. Both P2X (${\alpha}$,${\beta}$-MeATP) and P2Y (UTP) stimulation induced changes in the cell morphology (initial shrinkage and blob formation on the surface) reversibly. Exocytotic membrane trafficking events were monitored with the membrane-bound fluorescent dye, FM1-43 using confocal microscopy. In spite of the similar Ca$\^$2+/ responses, UTP was far less effective in triggering exocytosis than ${\alpha}$,${\beta}$ -MeATP. Since serotonin is reportedly stored in the secretory granule of PNECs, we directly examined whether the aforementioned agonists elicit release of serotonin using carbon fiber electrode-amperometry. In accordance with the results of FM1 -43 experiments, ${\alpha}$,${\beta}$-MeATP efficiently evoke serotonin secretion while not with UTP. In summary, the P2X-mediated Ca$\^$2+/ influx plays crucial roles in the exocytosis of RPNECs. Although a global increase in [Ca$\^$2+]$\sub$c/ might be related with the morphological changes, a sharp rise of [Ca$\^$2+/]$\sub$c/ in the putative sub-plasmalemmal ‘microdomains’ might be a decisive factor for the exocytosis.

• 한국환경과학회지
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• 제17권6호
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• pp.581-589
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• 2008

This study was carried out to evaluate the effect of water quality of cooling tower on Legionella pneumophila disinfection using Ru/Ti electrode. The influences of parameters such as pH, turbidity, $CaCO_3$ and TOC were investigated using laboratory scale batch reactor. Oxidants such as free Cl, $ClO_2,\;H_2O_2\;and\;O_3$ were measured. The results showed that all of the water quality parameters of cooling tower had deteriorated disinfection of Legionella pneumophila. When the turbidity, $CaCO_3$ and TOC was increased, oxidants which was generated during electrolysis was decreased. pH, free Cl, $ClO_2\;and\;H_2O_2$ concentration were decreased with the increase of pH, whereas $O_3$ concentration was increased with the increase of pH. The order of effect of water quality on the disinfection performance for Legionella pneumophila was turbidity > $CaCO_3$ > TOC > pH. To obtain the safety standard (1000 CFU/L), the simultaneous increase current and NaCl dosage was needed.

• 농업과학연구
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• 제9권2호
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• pp.507-518
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• 1982

Typic Udipsamment 토양(土壤)에 생장하고 있는 red pine (Pinus radiata) 조림지의 biogeochemistry가 Wisconsin의 central sand plains에서 조사(調査)되었다. Biomass와 net primary production은 각각 106Mg/ha 및 110Mg/ha/yr이었다. 식생(植生) 내(內)의 양료 농도는 2-3년생(年生) 침엽(針葉)에서 가장 많았고 그 다음은 당년생(當年生) 침엽(針葉), 당년생(當年生) 초지(梢枝), 수피, 생지(生枝), 고사지(枯死枝), 수간생성물, 수간 순(順)이었다. 조사된 수체(樹體) 성분에 있어서 당년생(當年生) 초지(梢枝)를 제외하고는 양료의 농도가 상부 3분지 1 부위(部位)에서 가장 높았고, 하부(下部) 3분지 1 부위(部位)에서 가장 낮았다. 식위(植位) 내(內)의 전체 양료는 N($222kg\;ha^{-1}$), Ca(217), K(85), Mg(38), S(31), P 순(順)이었다. 생태계 내(內)의 토양은 가용(可溶) P.K, Ca, Mg, S의 60-80%를 함유하고 있었다. N과 S의 약간의 급원(給源)이 강수(降水)인 반면에 Ca, Mg, P, K의 대부분은 토양풍화(土壤風化)로서 공급되었다. 조사양료의 용탈량(溶脫量)은 7 kg ha/yr미만이지만 S의 경우는 12kg ha/yr 이었다. Throughfal에 의(依)해서 N, K, S는 대부분 임상(林床)으로 순환되지만 Ca, Mg, P의 대부분은 litterfall에 의(依)해 돌아오는 것으로 사료된다. 엽(葉)의 양분용탈 때문에 throughfall의 양료의 함량은 강수의 함량보다 많았다. 강수(降水) 내(內)의 ammonium량(量)은 세근(細根)에 위한 흡수(吸水)때문에 토양상부(土壤上部) 7.5cm내(內)에서 3 가지 요인에 의하여 감소되었다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권10호
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• pp.504-508
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• 2001

The$(Sr_{1-x}Ca_x)TiO_3$(SCT) thin films are deposited on Pt-coated electrode $(Pt-TiN /SiO_2Si)$ using RF sputtering method at various deposition temperature. The crystallinity of thin films was increased with increased of deposition temperature n the temperature range of 200~500 $[^{\circ}C]$. The capacitance changes almost linearly in temperature ranges of -80~+90$[^{\circ}C]$. All SCT thin films used in the study the phenomena of dielectric relaxation with the increase of frequency, and the relaxation frequency is observed above 200[kHz]. V-I characteristics of SCT thin films show the increasing leakage current with the increases of deposition temperature.

• The Korean Journal of Ecology
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• 제17권3호
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• pp.277-286
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• 1994

수도권과 그 주변 지역의 33지소의 리기다소나무 숲에서 리기다소나무 잎과 잔뿌리의 주요이온의 함량을 정량하였다. 잎 속의 N, P, K 및 Mg 함량운 전년도 잎에 비해 당해연도 잎속에 높았지만, Al과 Ca은 그 반대였다. 잎 속의 N, P, K 및 Al 함랴은 지역간의 차이가 없었지만, Ca과 Mg 함량은 전원지에 비해 도심지에서 낮았다. 그러나 잎속의 N/Ca와 N/Mg의 비의 값은 전원지에보다 도심지에서 컸다. 표토 잔뿌리 속의 Mg 함량은 도심으로부터 거리가 멀어짐에 따라 증가하였으나, 심층토 잔뿌리 속의 Al 함량은 그 반대였다. 토양층 잔뿌리 속의Al 함량은 도심지보다 전원지에서 낮았다. 토양층 잔뿌리속의 Al 함량은 낙엽층의 잔뿌리에 비하여 2~3배 높았다. 그리고 표토보다 심층토에 존재하는 잔뿌리 속에 Al 함량이 높았다. 그러므로 수도권 지역에서 리기다소나무의 생장감소는 조직 속의 Ca과 Mg 부족, N/Ca과 N/Mg 비의증가 및 잔뿌리 생장에 대한 Al 독성에 있었다. 그리고 수도권 지역에서 잔뿌리의 비정상적인 분포는 산성토양에서 Al 독성에 의한 잔뿌리의 생장감소가 그 원인으로 해석된다.