• Applied Chemistry for Engineering
• /
• v.33 no.6
• /
• pp.618-623
• /
• 2022

The bipolar plate is a key component of the polymer electrolyte membrane fuel cell (PEMFC) that transfers reactants and electrons, discharges water and heat as by-products, and serves as a mechanical support for the membrane electrode assembly (MEA). Therefore, the flow field structure of the bipolar plate plays an important role in improving fuel cell performance. In this study, PEMFC performance was investigated with copper foams with different compressibility ratios applied to cathode bipolar plates using a 25 cm² unit cell. The total resistance decreased as the compressibility ratio of the metal foams increased, and, in particular, the charge transfer and mass transfer resistance were significantly improved compared to the serpentine flow field, lowering voltage loss in medium and high current density region. In the case of pressurized air reactant flow with serpentine structure, fuel cell performance was similar to that of a compressed metal foam flow field (S3) up to the medium current density region, but low performance appeared in the high current density region due to flow field structure limitations.

• Applied Chemistry for Engineering
• /
• v.32 no.4
• /
• pp.442-448
• /
• 2021

Flow field is an important parameter for polymer electrolyte membrane fuel cell (PEMFC) performance to have an effect on the reactant supply, heat and water diffusion, and contact resistance. In this study, PEMFC performance was investigated using Cu foam flow field at the cathode of 25 cm² unit cell. Polarization curve and electrochemical impedance spectroscopy were performed at different pressure and relative humidity conditions. The Cu foam showed lower cell performance than that of serpentine type due to its high ohmic resistance, but lower activation and concentration loss due to the even reactant distribution of porous structure. Cu foam has the advantage of effective water transport because of its hydrophobicity. However, it showed low membrane hydration at low humidity condition. The metal foam flow field could improve fuel cell performance with a uniform pressure distribution and effective water management, so future research on the properties of metal foam should be conducted to reduce electrical resistance of bipolar plate.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.1
• /
• pp.244-251
• /
• 2016

In this study, the relationship between flow characteristics and projection distance, depending on the shape was examined. A numerical investigation technique for fluid analysis of a foam monitor was developed for the prediction, comparison and validation of the actual injection performance. The foam monitor changes the flow pattern of fluid flow according to the shape, The fluid losses were calculated from the numerical investigation affecting the projection distance. The basic form of foam monitor was used as a designed shape in N. The modified model used the length increase model of the flow path, and straight line of the model. The inlet pressure was 6.5bar. The results showed that the length increase model of the flow path and straight line of the model in the nozzle projection distance had improved. The results comparing the error rates projection performance were well matched to the 7.43% obtained from the validity test of the analysis method.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2010.05a
• /
• pp.41-44
• /
• 2010

Presently, the apartment house is being constructed by the very various methods. Among them, the formwork having the process rate of 60~70% of the whole construction work is most important. So this study was analyzed comparing euro-form with aluminium-form in the formwork. A case study is using euro-form and aluminum-form in the framework, inquiry into a similar case construction site of below the 20 floor. Then this case analyzed efficiency; construction period, construction cost, workability. Consequently, the aluminum-form is more effective than the euro-form in the construction site of below the 20 floor.

• Journal of the Korea Institute of Building Construction
• /
• v.20 no.3
• /
• pp.245-252
• /
• 2020

Synthetic resin formwork is made of lightweight high-density polyethylene(HDPE). This study used a process flow chart that satisfies the system boundary (such as Cradle-to- Product shipmen ) required by ISO FDIS 13352 to evaluate the entire process of synthetic resin foam using. The entire life cycle inventory (LCI) database calculated from input energy sources, materials used, transportation methods, and manufacturing processes at the system boundary was analyzed. Based on the environmental impact assessment index methodology of the Ministry of Environment from the LCI data analysis of synthetic resin formwork, the environmental impact assessment was carried out through classification, normalization, characterization, and weighting process. The experimental results are as follows the amount of CO₂ (carbon) emission considering the number of conversions was about 32% lower than that of the Euroform. This shows that the use of synthetic resin formwork reduces material production by half compared to Euroform and reduces CO₂ (carbon) emissions.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.601-604
• /
• 2008

When the concrete is placed, the water, needed for hydration of the cement, is under 30% of W/C including bound and gel water. However, as minimum water content cause bad workability, the W/C have to be higher. Therefore, fresh concrete produce 10${\sim}$20% extra water. As those water remain entrapped air in the concrete, life of the structure is reduced because of the degradation caused by entrapped air. For that reason, if extra water is eliminated, it will be great to improve the durability of the structures. Therefore, this study was performed to verity the fundamental properties through the experiment on the dewatering system using the euro form for eliminating extra water. When the dewatering form was applicated, the compressive strength was increased by 16% than those of normal form. However, the increasing rate of compressive strength got lower as the height is higher. In terms of ultrasonic pulse speed and surface roughness, the dewatering form showed better results than the normal one.

• Proceedings of the KAIS Fall Conference
• /
• 2005.05a
• /
• pp.277-278
• /
• 2005

미생물 고정화를 위하여 PU 폼을 세 가지 처리 방법으로 처리하였다. 플라즈마 처리, 플라즈마 유도 그라프팅, 플라즈마 유도 그라프팅 후 플라즈마로 재처리 방법을 사용하였다. 플라즈마 처리는 bacteria adhesion에 큰 효과를 주지 못하였고, 아크릴산의 플라즈마 유도 그라프팅은 adhesion을 세 배 이상 증가시켰다. Bacteria의 adhesion 성능 향상은 표면의 친수성을 증가시키고 새로운 groove나 cavity들을 형성시킴으로 가능하였다. 반면, 그라프팅 후 plasma re-treatment는 미생물 고정화를 크게 향상시키지 못하였다. SEM 관찰을 통하여 대부분의 E.coli.는 groove나 cavities라는 shear-free area에 서식함을 알 수 있었다. PU폼의 bacteria adhesion은 미생물과 고분자 표면 사이의 정전기적 인력이나 van der Waals 인 력에 의해 주로 영향을 받는다고 사료된다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.12
• /
• pp.34-40
• /
• 2016

In ventilated seats for cars, air flow is generated by a fan and passed through a foam pad, foam filter, and seat cover. There is a significant loss of air flow in this process, and it is not easy to analyze the amount delivered to the driver. Another difficulty is the geometric complexity of the air flow passage inside the seats. In this paper, the air flow through a foam pad was analyzed. Proper modeling of the bumps in the ventilation mat was found to be important in the analysis. Air flow is lost when it passes through the porous pad foam, which was measured and used to correct the analysis results. The corrected analysis results were in a good agreement with the experimental results. The amount of air flow delivered to a driver was measured using an airflow cone. Only 35.7% of the air flow from the fan was delivered.

• 월간산업보건
• /
• s.259
• /
• pp.60-64
• /
• 2009

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.6
• /
• pp.577-584
• /
• 2018

In This study, length variation test, shock test, and noise test were conducted to evaluate the performance of synthetic resin form. In addition, the handling easiness of synthetic resin form was examined through field application. Results of both thermal length variation test and shock test satisfied the KS standards. for noise test, the result of uro-form was 106.7dB(A) in average while that of synthetic resin form was 100.4dB(A) in average. It is considered that the high sound pressure level of euro-form with this noise characteristic may have negative physical and psychological impact on people who are consistently exposed in the residential area. Finally, there was no warping or bulging of the mold during concrete placement in the field application. Also, the concrete surface finish of synthetic resin form was better than that of euro-form.