• Korean Journal of Radiology
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• 제21권11호
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• pp.1199-1209
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• 2020

The glymphatic system hypothesis is a concept describing the clearance of waste products from the brain. The term "glymphatic system" combines the glial and lymphatic systems and is typically described as follows. The perivascular space functions as a conduit that drains cerebrospinal fluid (CSF) into the brain parenchyma. CSF guided to the perivascular space around the arteries enters the interstitium of brain tissue via aquaporin-4 water channels to clear waste proteins into the perivascular space around the veins before being drained from the brain. In this review, we introduce the glymphatic system hypothesis and its association with fluid dynamics, sleep, and disease. We also discuss imaging methods to evaluate the glymphatic system.

• Near Infrared Analysis
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• 제2권1호
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• pp.43-53
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• 2001

A non-invasive spectroscopic method is presented for the measurement of pulmonary edema. Both early diagnosis and quantitative edema estimates were investigated. The spectroscopic determination of pulmonary edema involved the acquisition of diffuse reflectance spectra in the near-infrared (NIR) region with change in water concentration - water is the main constituent of edema fluid. Pulmonary edema was induced into the excised perfused lungs of seven animals by elevating the hydrostatic pressure. Estimates of edema were ascertained from a partial least squares regression of the measured spectral response. Actual edema was determined from the change (increase) in total lung weight. Estimates in relative lung weight increases due to in vitro edema were made with the near infrared spectra. The results revealed that fluid accumulation produced spectral changes in the O-H and C-H absorptions as well as scattering changes in the spectra. Histology of the lung was used to verify the presence or absence of interstitial and alveolar edema. Results demonstrated that near infrared spectroscopy might provide a new tool for clinical assessment of pulmonary edema.

• 한국수소및신에너지학회논문집
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• 제2권1호
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• pp.47-56
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• 1990

Pure titanium rods were oxidized by anodic oxidation, furnace oxidation and flame oxidation and used as a electrode in the photodecomposition of water. The maximum photoelectrochemical conversion efficiency(${\eta}$) was found for flame oxidized electrode ($1200^{\circ}C$ for 2 min in air), 0.8 %. Anodically oxidized electrodes have minimum photoelectrochemical conversion efficiencies, 0.3 %. Furnace oxidized electrode ($800^{\circ}C$ for 10min in air) has 0.5% phtoelectrochemical efficiency and shows a band-gap energy of about 2.9eV. The efficiency shows a parallelism with the presence of the metallic interstitial compound $TiO_{O+X}$(X < 0.33) at the metal-semiconductor interface, the thickness of the sub oxide layer and that of the external rutile scale.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book I
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• pp.258-267
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• 2003

Recently inside nano liposome particles or nano-emulsions which contain tough-melting physiology activity materials or the coefficient of low organism utilization promote the coefficient of organism utilization, so this part has been studied a lot because they can absorb selectly cosmetics, specially physiology activity materials, into the skin. Also, in particle size, cells interstitial lipid interval are 30~50nm, so nano-emulsions that the size is similar to 30~50 nm are made to study for absorbing quickly into the skin. And transparent skin which contains oils in common skin lotion dosage form has become the center of public interest. The used nano-emulsions in this study were unsaturated lecithin/co-surfactant! ethanol/ oil / water. And polysorbate 20/ polysorbate 80/ Dicetyl phosphate/hydrogenated .caster oil/ isoceteth-20/SLS were used in co-surfactant. The used oils were cyclomethicone and caprylic/capric triglyceride. The manufacturing process was that microfluidizer was fixed in 1000bar and transit times were changed from 1 to 10 times. From transparency and particle size, the transparency sequence was SLS> polysorbate 20= polysorbate 80> isoceteth-20> dicetyl phosphate >hydrogenated caster oil and the particle size was small. Specially cyclomethicone nano-emulsions, when we made unsaturated lecithin /SLS /ethanol/water/cyclomethicone, cyclomethicone 5％ was good for transparency. And 20％ of this was used for making transparent skin toner in common skin dosage form.

• 대한수의학회지
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• 제16권2호
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• pp.187-190
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• 1976

In order to approximate plasma volume, extracellular fluid volume and total body water volume of Korean native goats, measurements were made of the volumes of distribution of Evans blue, potasium thiocyanate and antipyrine. The results obtained in this work were summarized as follows: 1. Plasma volume showed a range of 50 to 72ml/kg with a mean of $62{\pm}6.2ml/kg$ (SD). 2. Blood volume showed a range of 69 to 98ml/kg with a mean of $85{\pm}7.9ml/kg$. 3. Extracellular fluid volume showed a range of 265 to 310ml/kg with a mean of $297{\pm}18.3ml/kg$. 4. Interstitial fluid volume showed a range of 204 to 261ml/kg with a mean of $236{\pm}16.8ml/kg$. 5. Intracellular fluid volume showed a range of 380 to 436ml/kg with a mean of $420{\pm}12.6ml/kg$. 6. The volume of total body water showed a range of 680 to 735ml/kg with a mean of $714{\pm}17.7ml/kg$.

• 환경영향평가
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• 제7권2호
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• pp.5-14
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• 1998

This study was performed to estimate interrelation between characteristics of sediment and nutrient releare from sediment in Dae-cheong lake. For the investigations, sediments were sampled in June and October 1997 at fish farms, embayment, and the main stream of Dae-cheong lake. Items for investigation are as follows; water content, weight loss on ignition(IG), porosity of sediment, Total Kjeldahl Nitrogen(TKN), content of element(H, N, C), nutrient release rate. Water content and porosity were measured to conjecture the physical trait and grain size. And weight loss on ignition was measured to determine the contents of organic substance. For the determination of nutrient release rate, $PO_4-P$ and $NH_4-N$ concentration of interstitial water and overlying water were measured. Release rate of nutrients which has direct influenced upon the water quality were 0.05-8.63mg-$P/m^2{\cdot}day$ and 4.99-36.56mg-$N/m^2{\cdot}day$. And it was found that release rate was measured higher in the 1st sampling than in the 2nd sampling. And for determination of the humus level of sediment, carbon and nitrogen content were measured by using elemental analyzer. Generally, C/N ratio is used to determine humus level of lake sediment. As a result of elemental analysis, C/N ratio was determined in the range of 7.64~11.55, so humus level of Dae-cheong lake sediment was estimated from mesohumic state to oligohumic state.

• 전기화학회지
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• 제22권1호
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• pp.13-21
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• 2019

프러시안 블루 유사체(Prussian blue analogue; PBA)는 두 종류의 전이금속이 시안화물 리간드와의 배위결합을 통해 서로 연결되어 만들어진 구조체이다. PBA는 넓은 골격구조를 통해, 다양한 이온의 가역적 삽입/탈리를 가능하게 할 뿐 아니라, 두 종류의 전이금속이 반응하여 높은 비용량을 구현한다. 또한, PBA는 상온에서 수용액 상에서의 공침반응을 통해 합성 되기에, 경제적이며 친환경적으로 생산된다. 하지만, 결정의 형성이 빠르게 진행되며, 수용액 상에서 발생하기에 결정 내 공공격자결함(Vacancy)과 결정수(Crystal water)가 발생하기 쉬우며, 이는 전기화학적 성능에 영향을 미친다. 따라서 이러한 공공격자결함 및 결정수의 생성 억제를 통해 PBA의 전기화학성능 향상에 대한 연구가 활발하게 진행되고 있다. 공공격자결함의 경우 반응속도 제어를 통해 합성단계에서 제어 되며, 결정수는 합성 후 진공 열처리 및 산화제와 복합체 형성을 통해 제거할 수 있다. 뿐만 아니라 PBA의 구조 내에 비활성 전이금속 도핑을 통해 상기 결함들로 인해 PBA가 전기화학 반응 중에 겪는 구조적 불안정성을 해소할 수 있다.

• 전기화학회지
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• 제10권4호
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• pp.295-300
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• 2007

A new characterization method using a porous plug model was proposed to determine the degree of sulfonation (DS) of ionomer binder with respect to the membrane used in membrane-electrode assemblies (MEAs) and to analyze the fraction of proton pathways through ionomer-catalyst combined electrodes in MEAs for polymer electrolyte fuel cells (PEFCs). Sulfonated poly(ether ether ketone) was prepared to use a polymeric electrolyte and laboratory-made SPEEK solution (5wt.%, DMAc based) was added to catalyst slurry to form catalyst layers. In case of the SPEEK-based MEAs in this study, DS of ionomer binder for catalyst layers should be the same or higher than that of the SPEEK membrane used in the MEAs. The porous plug model suggested that most of protons were via the ionomer binder (${\sim}92.5%$) bridging the catalyst surface to the polymeric electrolyte, compared with the pathways through the alternative between the interstitial water on the surface of ionomer binder or catalyst and the ionomer binder (${\sim}7.3%$) and through only the interstitial water on the surface of ionomer or catalyst (${\sim}0.2%$) in the electrode of the MEA comprising of the sulfonated poly(ether ether ketone) membrane and the 5wt.% SPEEK ionomer binder. As a result, it was believed that the majority of proton at both electrodeds moves through ionomer binder until reaching to electrolyte membrane. The porous plug model of the electrodes of MEAs reemphasized the importance of well-optimized structure of ionomer binder and catalyst for fuel cells.

• 지질공학
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• 제6권3호
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• pp.155-163
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• 1996

현행 ASTM C227-90은 모르타봉 시험법에 대한 규정인데 동 규정에 의하면 시험용 모르타르봉으 제작에 골재와 시멘트를 각각 675g과 300g을 쓰도록 무게비로 제시하고 있으며 제작된 모르타르봉의 초기길이 측정시기는 $24{\pm}2$시간으로 규정되어 있다. 또한 모르타르봉의 팽창원인을 알카리-골재반응에 두고 있다. ASTM C490-93a는 모르타르봉의 제작방법과 팽창률 계산방법이 소개되어 있는데 규정에 의하면 계산공식으 분모 G값을 10" 혹은 250mm로 고정시키고 있다. 본 연구는 위에 소개한 내용에 대한 실험적 연구를 통하여 다음과 같은 결론에 도달하였다. 첫째, 모르타르봉의 팽창은 알카리-골재반응만에 의한 것이 아니고 그 외 간극수와 겔수의 복합적인 작용에 의한 것이므로 ASTM C227-90의 내용을 일부 수정할 필요가 있다. 둘째, 골재에 의한 모르타르봉의 팽창원인 즉 알카리-골재반응과 간극수에 의한 팽창량을 알기 위하여는 골재와 시멘트의 배합비를 무레비 대신에 부피비로 제시함이 바람직 하다. 세째, ASTM C227-90과 ASTM C490-93a에서 제시한 모르타르봉의 초기길이 측정시기와 팽창률 계산방법은 더욱 정밀한 계산결과를 얻기 위하여 부분적인 수정이 필요하다.

• Clinical and Experimental Reproductive Medicine
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• 제27권2호
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• pp.133-144
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• 2000

Objective: Several water channels (aquaporins; AQP) that belong to the MIP (major intrinsic protein) family have identified. In the selected tissues including red blood cells or renal tubules, water movements are abundant and/or physiologically important. Unexpectedly, a high water permeability of human and ram sperm has been reported. Recent studies showed that AQP7 and AQP8 are present in testes, so that the high water permeability of human sperm suggested to be mediated by AQPs. Method: To identify the identity of aquaporins expressed in testes, RT-PCR was performed using degenerative primers, which were designed to correspond to highly conserved sequences surrounding the Asn-Pro-Ala (NPA) motifs in the aquaporins. New expressed AQP series were reconfirmed by immunohistochemical study using rabbit polyclonal antibodies. Results: DNA sequencing of PCR products revealed that AQP2 and AQP3 mRNA as well as AQP7 and AQP8 are expressed in human and rat testes. In human and rat testes, AQP2 are expressed in spermatozoa, interstitial cells and myofibroblasts and AQP3 are expressed in myofibroblasts of semineferous tubules on immunocytochemical stain. Conclusion: These results indicate that multiple aquaporins are expressed in testes, and that they may have important roles in the spermatogenesis and the germ cell function of testis.