• Journal of the Korean Solar Energy Society
• /
• v.28 no.2
• /
• pp.58-63
• /
• 2008

This study has analysed power output characteristics of transparent thin-film PV module depending on incidence angle and azimuth. The experiment results showed power outputs of transparent thin-film PV module applied to full-scale mock up model on slope of $90^{\circ},\;30^{\circ},\;0^{\circ}$ to the south. The simulation results was evaluated power outputs of transparent thin-film PV module depending on incidence angle and azimuth after calibrating the experimental and computed data. As a result. the best power output performance of transparent thin-film PV module was obtained at slope of $30^{\circ}$ to the south, producing the annual power output of 977kWh/kWp. The annual power output data demonstrated that the PV module with a slope of $30^{\circ}$ could produce a 68 % higher power output than that with a slope of $90^{\circ}$ with respect to the inclined slope of the module, Furthermore, the PV module facing south showed a 22 % higher power output than that facing to the east in terms of the angle of the azimuth, Specipically. the varying power output with incidence angle of PV module can be resulted from the influence of incidence angle modifier of glass on PV module. That is, the solar energy transmission can be reduced as an increase of incidence angle of PV module. Therefore, when the inclined slope of the PV module was over $70^{\circ}$ there was a significant reduction of power output, and this was caused by the decrease of solar energy transmission in the transparent thin-film PV module.

• Archives of design research
• /
• v.17 no.1
• /
• pp.37-48
• /
• 2004

Keiji Kobo is a unique self-generated design research group in Japan, which was founded in 1928 when Bauhaus movement was in its peak, and which lasted ten years until the end of the Second World War, when any activity of the group became virtually impossible due to the war. With insight to see the future, the group aimed at Modern Design advocating a new spirit in architecture, and played a significant role in prosperity of Japanese Modern Design assimilating Western design trends. Pursuing of craft works for everyday life--practical furniture works--Keiji Kobo actively executed various projects to realize modern philosophy. The range of the works of this group was very large: survey, mock-up, experiment, research, exhibition, lecture, order-based sale, advertising and writing. The works of the group were oriented to serious academicism, not compromising with commercialism. Considering the peculiar political situation such as Japanese Militarism, the spirit of functionalism that the group pursued was surprisingly academical and pure. This group was relatively small and clumsy, which lasted as short as around ten years. However, strong motivation was in their seemingly quiet movements, and the influence of the group cannot be underestimated even with today's criteria. There were a number of pioneers who contributed to today's prosperity of Japan and Keiji Kobo can be estimated to be one of the pioneers in the field of design. It was found that the contemporary intellectuals hoped that the committment and activity of the group would contribute to modernization of the life quality of ordinary people. In a sense, Keiji Kobo can be estimated to be a little Japanese equivalent for Bauhaus that could not fully bloom.

• Land and Housing Review
• /
• v.14 no.4
• /
• pp.111-120
• /
• 2023

Indoor air quality has become increasingly important with the increase in time spent in residential environments, impact of external fine dust, yellow dust, and the post-COVID 19 pandemic. Residential mechanical ventilation plays a key role in addressing indoor air quality. The legal standard for residential air changes per hour in Korea is 0.5 ACH. However, there are no standards for the location of supply and return vents. This study atempts to analyze the impact of ventilation performance based on the location of supply and return vents. An experiment was conducted using the CO₂ tracer gas concentration decay method in a mock-up house set inside a large chamber to minimize external influences. The experimental results indicated that the commonly used combination of 2 supply and 2 return vents in living room spaces had a lower mean age of air than the combination of 1 supply and 2 return vents. Using multiple supply and return vents had lower mean age of air than using just 1 supply and 1 return vent.

• Journal of Nutrition and Health
• /
• v.51 no.5
• /
• pp.433-444
• /
• 2018

Purpose: This study examined the status and needs of school-based nutritional education programs for reducing sugars intake in elementary schools. Methods: A total of 230 elementary nutrition teachers participated in this study through an online survey in July 2017. Results: Approximately one-third of the schools conducted nutrition education on reducing sugars intake as a main topic. The most frequent educated grade and education period were $4^{th}$ and $3^{rd}$ grade, and once a year. Most of the nutrition teachers answered that nutrition education related to reducing sugars intake for children was necessary. The nutrition teachers answered that first graders were the recipients in most need of nutrition education for reducing sugars but, realistically, third graders were the most suitable for nutrition education. The appropriate education topics were limited to the lower grades, such as sugars consumption related health problems, foods containing high sugars, and behaviors to reduce sugars intake; however, a wider variety of topics were selected for the upper grades. The experiment was considered to be an effective educational method for both the lower and upper grades. The most appropriate nutrition education media appeared to be a mock-up in the lower grades, and an experiment kit in the upper grades. Games and videos were highly considered to be effective media to educate students in reducing sugars consumption by voluntary participation in free time in the classroom in both the lower and upper grades. Conclusion: Nutrition education programs focusing on sugars intake reduction were conducted in some elementary schools, but the training time was short and the types of activities were limited. The perception and demand for nutrition education was very high. Therefore, the development and dissemination of elementary school-based nutritional education programs for sugars intake reduction is urgently needed. Moreover, to develop an effective nutrition education program, the education environment and demand in the field should be fully considered.

• Journal of Soil and Groundwater Environment
• /
• v.8 no.2
• /
• pp.62-69
• /
• 2003

The aim of research is the evaluation of the $Cr^{6+}$ emission features of the liquid injection through emission experiments in varying conditions, based on a field-mixing ratio. The results showed that the content of $Cr^{6+}$ content in cement measured had an Ordinary Potland Cement (OPC) of 25.3 mg/kg, which constitute the largest portion among the other materials. Likewise, the emission experiment of homo-gel and sand-gel generally satisfied the standard of KSLT (Korea Standard Leaching Test) in waste of 1.5 mg/L, but in case of the standard of KSLT in soil the emission of OPC $Cr^{6+}$ of 4.85 mg/kg. These conditions is a little exceeded the criteria in the ‘Ga’ area in terms of Korea Soil Environmental Preservation Law. In addition, results generated by the mock-up injection facilities revealed that $Cr^{6+}$ emission increased as Water/Cement and injection pressure increased. At injection pressure higher than 4 kg/㎤, $Cr^{6+}$ emission exceeded the water preservation standard of 0.5 mg/L. Similarly, a pattern experiment of C $r^{6+}$ emission according to pH was conducted, in order to evaluate the $Cr^{6+}$ emission features of grout materials in leachate below pH 5 such as pH 4 acid rain or landfill. Results show that $Cr^{6+}$ emission dramatically increased in high acidic or basic state. It indicates that $Cr^{6+}$ emission will probably increase in an environment where grout materials are injected. On the other hand, concentration of leachate was determined in areas where grout materials are used. The results show that the concentration of emission in an ultra purity condition does not manifest intensity, and is affected in the OPC>MC>SC order. It means that the pollutants or $Cr^{6+}$ emission increases with decreasing concentration. As such, $Cr^{6+}$ emission will probably exceed the countermeasure criteria according to the types of gout materials. Similarly, high pressure or injection will cause increased $Cr^{6+}$ emission. Therefore, the selection of materials or mixing ratio should be considered in general as well as according to specific industries, based on the strength and pH of $Cr^{6+}$ emission.

• Korean Journal of Environmental Biology
• /
• v.32 no.1
• /
• pp.58-67
• /
• 2014

The outdoor mass cultivation is not possible for microalgae in Korea all year round, due to cold winter season. It is not easy to maintain proper level of productivity of microalgae even in winter. To prevent a drastic decrease of temperature in a greenhouse, two layers were covered additionally, inside the original plastic layer of the greenhouse. The middle layer was made up of plastic and the inner layer, of non-woven fabric. Acrylic transparent bioreactors were constructed to get more sunlight, not only from the upper side but also from the lateral and bottom directions. In winter at freezing temperatures, six different culture conditions were compared in the triply covered, insulated greenhouse. Wastewater after anaerobic digestion was used for the cultivation of microalgae to minimize the production cost. Water temperature in the bioreactors remained above $10^{\circ}C$ on average, even without any external heating system, proving that the triple-layered greenhouse is effective in keeping heat. Algal biomass reached to 0.37g $L^{-1}$ with the highest temperature, in the experimental group of light-reflection board at the bottom, with nitrogen and phosphorus removal rate of 92% and 99%, respectively. When fatty acid composition was analyzed using gas-chromatography, linoleate (C18 : 3n3) occupied the highest proportion up to 61%, in the all experiment groups. Chemical oxygen demand (COD), however, did not decrease during the cultivation, but rather increased. Although the algal biomass productivity was not comparable to warm seasons, it was possible to maintain water temperature for algae cultivation even in the coldest season, at the minimum cost.

• Journal of Biomedical Engineering Research
• /
• v.25 no.5
• /
• pp.421-430
• /
• 2004

Clinically, it is almost impossible for a physician to distinguish subtle changes of frequency spectrum by using a stethoscope alone especially in the early stage of thrombus formation. Considering that reliability of mechanical valve is paramount because the failure might end up with patient death, early detection of valve thrombus using noninvasive technique is important. Thus the study was designed to provide a tool for early noninvasive detection of valve thrombus by observing shift of frequency spectrum of acoustic signals with computer aid diagnosis system. A thrombus model was constructed on commercialized mechanical valves using polyurethane or silicon. Polyurethane coating was made on the valve surface, and silicon coating on the sewing ring of the valve. To simulate pannus formation, which is fibrous tissue overgrowth obstructing the valve orifice, the degree of silicone coating on the sewing ring varied from 20％, 40％, 60％ of orifice obstruction. In experiment system, acoustic signals from the valve were measured using microphone and amplifier. The microphone was attached to a coupler to remove environmental noise. Acoustic signals were sampled by an AID converter, frequency spectrum was obtained by the algorithm of spectral analysis. To quantitatively distinguish the frequency peak of the normal valve from that of the thrombosed valves, analysis using a neural network was employed. A return map was applied to evaluate continuous monitoring of valve motion cycle. The in-vivo data also obtained from animals with mechanical valves in circulatory devices as well as patients with mechanical valve replacement for 1 year or longer before. Each spectrum wave showed a primary and secondary peak. The secondary peak showed changes according to the thrombus model. In the mock as well as the animal study, both spectral analysis and 3-layer neural network could differentiate the normal valves from thrombosed valves. In the human study, one of 10 patients showed shift of frequency spectrum, however the presence of valve thrombus was yet to be determined. Conclusively, acoustic signal measurement can be of suggestive as a noninvasive diagnostic tool in early detection of mechanical valve thrombosis.