Although the age-standardized incidence of gastric cancer has decreased in Korea, it remains the second most common type of cancer. The purpose of this study was to analyze the phospholipid fatty acid compositions of gastric mucosa in gastric cancer. Cancerous mucosa and noncancerous mucosa adjacent to cancerous tissues were obtained from 29 patients who had undergone gastrectomy for gastric adenocarcinoma. Phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidylserine (PS) were separated from phospholipids by thin-layer chromatography, and fatty acids were analyzed by gas chromatography. In cancerous mucosa, saturated fatty acids of total phospholipids and stearic acid of PE and PC contents as well as total phospholipids were significantly more abundant than in noncancerous tissues. The ratios of ω6 fatty acid products to linoleic acid of PC, PE, PI, and PS contents as well as total phospholipids were significantly higher in cancerous mucosa than in noncancerous mucosa. Arachidonic acid levels of PE and PI were significantly higher, but the PC level was lower in cancerous mucosa. These results suggest that the characteristic differences in fatty acid compositions of phospholipids and their subfractions shown in gastric cancerous mucosa may be affected by changes in lipid metabolism in gastric carcinogenesis. Further studies on structural and functional changes in phospholipids related to gastric carcinogenesis will be needed.

Aluminum nitride (AlN) has excellent electrical insulation property, high thermal conductivity, and a low thermal expansion coefficient; therefore, it is widely used as a heat sink, heat-conductive filler, and heat dissipation substrate. However, it is well known that the AlN-based materials have disadvantages such as low sinterability and poor mechanical properties. In this study, the effects of addition of various amounts (1-6 wt.%) of sintering additives Y2O3 and Sm2O3 on the thermal and mechanical properties of AlN samples pressureless sintered at 1850oC in an N2 atmosphere for a holding time of 2 h are examined. All AlN samples exhibit relative densities of more than 97%. It showed that the higher thermal conductivity as the Y2O3 content increased than the Sm2O3 additive, whereas all AlN samples exhibited higher mechanical properties as Sm2O3 content increased. The formation of secondary phases by reaction of Y2O3, Sm2O3 with oxygen from AlN lattice influenced the thermal and mechanical properties of AlN samples due to the reaction of the oxygen contents in AlN lattice.

To improve the mechanical properties of aluminum, graphene has been used as a reinforcing material, yielding graphene-reinforced aluminum matrix composites (GRAMCs). Dispersion of graphene materials is an important factor that affects the properties of GRAMCs, which are mainly manufactured by mechanical mixing methods such as ball milling. However, the use of only mechanical mixing process is limited to achieve homogeneous dispersion of graphene. To overcome this problem, in this study, we have prepared composite materials by coating aluminum particles with graphene by a self-assembly reaction using poly vinylalcohol and ethylene diamine as coupling agents. The scanning electron microscopy and Fourier-transform infrared spectroscopy results confirm the coating of graphene on the Al surface. Bulk density of the sintered composites by spark plasma sintering achieved a relative density of over 99% up to 0.5 wt.% graphene oxide content.

This study would present a risk analysis method to evaluate stable tap water supply in a multi-regional water supply system and propose a measure for the evaluation of the effect of the conjunctive operation of the multi-regional water supply system using this. Judging from the vulnerability for the crisis response of the entire N. multi-regional water supply system, as compared to the result of Scenario 1 in which no conjunctive pipes were operated, it was found that in Scenario 2, in which conjunctive pipes were partially operated, the vulnerability of crisis response decreased by about 30.6%, and as compared to Scenario 3, the vulnerability of crisis response decreased by 86.2%. In setting a plan for stable tap water supply in N multi-regional water supply system, using the estimated value and the method for the evaluation of the vulnerability of crisis response by pipe, by interval and by line, it is judged that this can be utilized as a basis for the judgment of the evaluation of the operation or the additional installation of conjunctive pipes.

이 논문은 재료의 전기 전도도 분포를 재구성하는 전기임피던스 단층이미지 기법(electrical impedance tomography; EIT)을 제시한다. 이 문제는 구조물 표면의 전극에서 측정된 전위와 계산된 전위의 차를 최소화하여 전기 전도도의 공간적 분포를 재구성하는 최적화 문제로 정의된다. 전류 입력 시 전위를 구하는 정해석 문제의 수학적 모델로서 완전전극모델(complete electrode model; CEM)을 사용하였다. 완전전극모델은 전기 포텐셜에 대한 라플라스 방정식과 전류 입력에 따른 경계조건들로 구성되는 경계값 문제이다. 완전전극모델 해의 정확성을 검증하기 위하여 유한요소법을 이용해 구한 원형 구조물의 전위해와 Technology Computer Aided Design(TCAD) 소프트웨어를 사용해 얻은 결과를 비교하였다. 완전전극모델의 지배방정식과 경계조건을 구속조건으로 하는 최적화 문제를 라그랑주 승수법(lagrange multiplier method)을 이용해 비구속 최적화 문제로 전환하고 라그랑지안의 1차 최적화 조건으로부터 전극에서의 전위 차를 최소화하는 최적의 전기전도도 분포를 도출 하였다. 원형 균일영역의 전기 전도도 분포를 재구성하는 역해석 예제를 통해 완전전극모델 기반 EIT 프레임워크의 적용성을 검토하였다.

Chlor-alkali (CA) membranes as key materials to generate chlorine gas and sodium hydroxide are composed of sulfonic acid layer (S-layer) and carboxylic acid layer (C-layer) to provide fast sodium ion transport and slow hydroxide ion diffusion, respectively. Aciplex F, a representative CA membrane is made in a double layer form via thermal adhesion of both layers after each single layer film is independently fabricated. Unfortunately, the membrane fabrication induces delamination particularly in their interface as a result of hydroxide ion diffusion occurring during CA operation, leading to rapid increase in electrochemical overpotential. In this study, selective chemical conversion technique was developed to solve the delamination issue. Their effectiveness was proved by applying the same concept to a wide range of PFSA membrane.

Anion exchange membrane (AEM) with fixed charged cationic groups can selectively transport anionic molecules such as hydroxide anions. The AEM materials have been widely used in the wide range of applications such as polymer electrolyte fuel cells, water electrolysis, and reverse electrodialysis and electrodialysis. Commercially available AEM materials show high electrochemical resistance owing to their chemical architectural features leading to less separated hydrocarbon morphologies. Very low solubility to casting solvents and weak chemical durability to alkaline atmosphere of the AEM materials also makes it difficult to make thin and tough AEM membranes. In this study, AEM materials composed of perfluorinated architectures with improved chemical durability and intrinsically well separated morphologies were developed and evaluated.

Saline water electrolysis (SWE) is an electrochemical technology to directly generate valued chemicals such as chlorine gas (Cl2), hydrogen (H2), and sodium hydroxide (NaOH) by applying electric energy. The key materials in SWE are cation exchange membranes with high selectivity to sodium ions under chemically harsh SWE conditions. The representative SWE membranes are perfluorinated double layered membranes composed of perfluorinated sulfonic acid layer and carboxylic acid layer to transport sodium ions rapidly and to prevent the passage of hydroxide ions, respectively. The commercially available membranes are, however, suffering from delamination issues occurring in their interface. In this presentation, delamination-free membrane fabrication processes will be addressed.

The anion exchange membrane (AEM) has a structure having a group of positively charged ions inside, and selectively permeates the anion of the electrolyte. In addition, excellent ion conductivity and chemical durability, and highly reliable electrochemical performance are required. However, commercially available AEMs have a hydrocarbon-based backbone. It is difficult to make the thin film because of low solubility. As a result, it has low ionic conductivity and high area resistivity and shows limitations in electrochemical applications. In this study, a perfluorinated ionomer-based anion exchange membrane with excellent chemical stability is prepared and shows enhanced anion conductivity in electrochemical applications.

The estimation method of economical leakage management target utilized upon planning business for improvement of revenue water ratio in South Korea is presented and applicability of methods developed in this study is assessed through application on site. With a consideration of revenue water ratio in application target area, estimation method of long-term economical leakage management target is applied. Three leakage reduction methods such as replacement of residual aged pipe, leakage investigation and restoration and water pressure management are applied with a consideration of characteristics of site. Due to difficulty of obtaining data, analysis of cost/benefit by leakage reduction methods is performed by applying method of leakages estimation equation among statistical methods. As a result of application, revenue water ratio corresponding to long-term economical leakage management target is 91.6 %.

양이온(Na+) 및 음이온(Cl-)이 각각의 CEM과 AEM을 통해 선택적으로 분리되어 담수로 이동할 때 발생되는 전위 차와 산화/환원(redox couple)형 전해질을 포함하고 있는 전극에서 발생하는 전류를 이용하여 전기 에너지로 전환시키는 에너 지변환장치이다. RED 시스템의 핵심소재 중 하나인 이온교환막은 높은 출력 밀도를 달성하기 위해 1) 낮은 팽윤거동, 2) 적 절한 이온교환능, 3) 높은 이온전도도, 4) 높은 이온선택성을 만족시켜야 한다. 본 논문에서는 이를 만족시키는 소재 및 이온 교환막의 연구동향 및 전망에 대해 설명하였다.

본 연구에서는 신갈나무와 졸참나무 임분의 입지환경인자 및 기후인자 자료를 활용하여 출현확률을 평가하였으며, 자료 분석은 Binary logit model을 이용하였다. 추정 결과, 신갈나무는 해발이 높고, 산복이나 산정의 지형에서 확률이 높게 나타난 반면 졸참나무는 대체로 해발고가 높지 않으며, 평탄지와 완구릉지에 비하여 산록과 산복의 지형에서 확률이 증가되는 경향이 나타났다. 그 외 적색산림토양군의 토성을 가지는 지형과 점토군이 아닌 미사군과 모래군으로 갈수록 출현확률이 높아지는 공통적인 특성이 나타났다. 본 연구의 결과는 장기적인 산림경영 측면에서 조림수종 선정에 유용하게 활용 될 수 있을 것으로 사료된다.

Ionomers are polymeric materials containing fixed charged ions (e.g., – SO3 -) to transport their counter ions (e.g., H+, Li+, Na+ and so on) selectively and have been widely used as key components for membrane and unit cell formation targeted for renewable energy generation (e.g., polymer electrolyte membrane fuel cells(PEMFC), redox flow batteries, and reverse electrodialyses) and valued chemical production (e.g., water and brine electrolysis). There are advantages such as high processability, easy solvent evaporation, and chemical inertness, when the ionomers are in the dissolved or dispersed states in water-alcohol mixtures to be applied for these applications. Unfortunately, it is difficult to make homogeneous solution or dispersion using the ionomers with hydrophilic levels undissolved in water. In this study, water-alcohol nanodipsersion with perfluorinated or hydrocarbon sulfonic acid ionomers are fabricated and their feasibilities as PEMFC and electrolysis materials are evaluated.