• Applied Microscopy
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• 제26권1호
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• pp.47-57
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• 1996

This study analysed the transport properties of bladder mucosa known as the typical system of 'tight epithelia' by using TEM observation with both rapid freeze-fracture electron microscopy and thin-section method and mainly analysed the cellular characteristics of turtle bladder epithelial cells. The bladder epithelium, like other tight epithelia, consists of a heterogenous population of cells. The majority of the mucosal cells are the granular cells and may function primarily in the process of active $Na^+$ reabsorption in turtle bladder. The remaining two types of cells are rich in mitochondria and is believed to be res-ponsible for a single major transport system, namely, $H^+$ transport by A-type of cell and urinary $HCO_{3}^-$ secretion by B-type of cell. As viewed in freeze-fracture electron micrograph, the tight junctions form a continuous tight seal around the epithelial cells, thus restricting diffusion in tight epithelia. In addition, the apical surface membranes have a population of rod-shaped intramembranous particles (IMPs). It is believed that these IMPs probably represent the components of the proton pump. However, it is likely that these characteristics of the apical transporter remain to be clarified in tight epithelial cells.

• 방사선산업학회지
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• 제17권2호
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• pp.191-197
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• 2023

Abstract KOMAC(Korea Multi-Purpose Accelerator Complex, KAERI) has been operating a 100 MeV proton accelerator and is going to produce ⁶⁸Ga isotope which is useful for diagnosis of cancer. So, it is necessary to develop a transport container for radio-activated targets. In this study, we carry out shielding analysis and structural analysis for the radio-activated target transport container using simulation programs. According to the Type A standard, the transport container includes an inner container and an overpack container. The main material of inner container is lead, and the shape is cylindrical with diameter of 152mm, height of 142mm and weight about 29 kg. It is planned to verify the possibility of field application through production of the transport container prototype in the future.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2005년도 수소연료전지공동심포지움 2005논문집
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• pp.233-240
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• 2005

A series of inorganic-organic hybrid membranes were prepared with a systematic variation of titanium dioxidenanoparticles content. Their water uptake, methanol permeability and proton conductivity as a function of inoranic oxide content were investigated. The results obtained show that the inorganic oxide network decreases the proton conductivity and water swelling. It is also found that increase In inorganic oxide content leads to decrease of methanol permeability. In terms of the morphology, membranes are homogeneous and exhibit a good adhesion between inorganic domains and the polymer matrix. The properties of the composite membranes are compared with the standard nafion membrane.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.542-545
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• 2008

Experiments have been performed to investigate effects of pulsating cathode flow on a 10-cell proton exchange membrane fuel cell (PEMFC) stack. For all the experiments, the flow rate, temperature and relative humidity of hydrogen at the anode inlet are fixed. The effects of the pulsating frequency, amplitude and flow rate at the cathode inlet on performance of 10-cell PEMFC are examined. The polarization and power curves show that the power output and limiting current is substantially increased when the pulsating component is added to cathode flow channel. The maximum power output increases by up to 38% and enhancement of the overall performance is more pronounced at lower flow rate region.

• The Korean Journal of Ceramics
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• 제4권2호
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• pp.136-140
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• 1998

This work demonstrates a method for modeling of electrical conductivity in high-temperature proton-conducting oxides. Total conductivity was calculated assuming that it comprises partial conductivities contributed by protons, oxygen ions and electron holes. From the polt $\sigma_{tot}$ vs. $po_2\;{1/4}$ in wet atmosphere, thermodynamic and kinetic parameters were obtained representing transport properties such as concentration and mobility of the charge-carrying defects. The formulas for the calculation of partial conduction were derived based on the defect structure of HTPCs. Illustrative calculation were made for $SrCe_{0.95}Yb_{0.05}O_{2.975}$ system.

• 미생물학회지
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• 제30권6호
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• pp.432-437
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• 1992

When $H^{2}$ was provided as the electron donor, optimum $O_{2}$ levels for growth of Wolinella succinogenes ATCC 29543 were 2% and 8% on brucella agar and in brucella broth, respectively. No growth occurred under 21% $O_{2}$, and scant or no growth occurred under anaerobic condition. $O_{2}$ uptake was inhibited by cyanide and 2-heptyl-4-hydroxyquinoline N-oxide. Protons were translocated out of the cell when oxygen was used as the terminal electron accetor. The $H^{+}$/O ratio with $H_{2}$ and formate as an electron donor were 1, 97 and 1.49, respectively. Proton translocation was inhibited by the protonophore carbonylcyanide m-chlorophenylhydrazone.e.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.194-196
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• 2005

A series of inorganic-organic hybrid membranes were prepared with a systematic variation of titanium dioxidenanoparticles content. Their liquid uptake, methanol permeability and proton conductivity as a function of inoranic oxide content were investigated. The results obtained show that the inorganic oxide network decreases the proton conductivity and liquid uptake. It is also found that increase in inorganic oxide content leads to decrease of methanol permeability. In terms of the morphology, membranes are homogeneous and exhibit a good adhesion between inorganic domains and the polymer matrix. The properties of the composite membranes are compared with the standard nafion membrane.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.279-279
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• 2012

In order to estimate the average migration lengths of $H_3O^+$ ions in amorphous ice, we conducted experiments of reactive ion scattering (RIS), low energy sputtering (LES), and reflection absorption IR spectroscopy (RAIRS) with an ultra-high vacuum (UHV) chamber. Dopped water-ice films were grown on the clean surface of Ru single crystal and analyzed with RIS, LES and RAIRS methods. The population changes of probe molecules, which were buried at a controlled distance from the surface, were monitored by those methods so that we can mesure the migration efficiencies. From the measured efficiencies, we evaluated the average migration lengths. This result is expected to give the information about the dynamics of proton in water-ice film.

• 한국잡초학회지
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• 제17권4호
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• pp.345-361
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• 1997

Photoassimilates translocate from regions of carbohydrate synthensis(source) to regions of carbohydrate utilization or storage(sink). In the source, assimilate loads into the phloem for long-distance transport. Current evidence suggests that there are twig loading mechanisms : one involves assimilate transfer via the apoplasm and then load into the phloem by carrier-mediated proton-sucrose cotransport, while the other involves movement through the continuous symplastic connections between the mesophyll cells and the phloem. Inspite of problems associated with the interpretation of experiments, the evidence for apoplastic loading remains convincing because the apoplastic loading systems explains well the observed accumulation capacity arid the selectivity of assimilate uptake by tile phloem.

• 공업화학전망
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• 제22권4호
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• pp.20-34
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• 2019

수소경제 시대의 도래와 함께 연료전지에 관한 연구가 크게 주목받고 있다. 그중 실험적으로 분석이 어려운 부분에 관하여 비용과 시간이 요구되는 실험적인 방법을 배제할 수 있는 모델링 기법인 전산유체역학(computational flow dynamics, CFD)이 큰 관심을 받고 있다. 연료전지의 연구에 주로 사용되는 전산유체역학에 관한 연구는 열분포, 유체의 흐름, 각종 반응물의 농도, 그리고 전기화학반응 등의 실험적인 분석이 현실적으로 불가능한 부분의 분석으로 통하여 실험을 줄이고도 많은 결과를 얻을 수 있는 연구가 활발하게 진행되고 있다. 본 기고문에서는 전산유체역학을 이용한 연료전지 내부에서 벌어지고 있는 각종 유체, 열, 전기화학반응 등에 관한 연구동향을 소개하고자 한다.