• Composites Research
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• v.15 no.1
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• pp.32-40
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• 2002

This study developed fabrication process of $SiC_p/Al$ metal matrix composites as electronic packaging materials by squeeze casting method. The $SiC_p$ preform were fabricated in newly designed preform mold using about 0.8 % of inorganic binder(SiO$_2$) and 5 vol.% of $Al_2O_3$fiber. To infiltrate the molten metal into the preform, fabrication condition such as the temperature and the pressure were selected. Applying the fabrication conditions, heat transfer analysis were preformed using finite element method and thus analyzed the temperature distribution and cooling characteristic during the squeeze casting. For the fabricated composites, impact toughness and thermal expansion coefficient were measured. The metal matrix composites developed in this study have 0.2~0.3 J impact toughness, $8~10 ppm/^{\circ}C$ thermal expansion coefficient and $2.9~3.0g/cm^3$density which is appropriate properties for electronic packaging application.

• Journal of Mushroom
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• v.2 no.3
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• pp.163-167
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• 2004

It shows that there is the fastest growth of S. crispa in the weak acid pH5. Also, it shows that S. crispa has the best environment in the MEF media. The next desirable one was as in this array: MES, MEI, YMF, YMM, YMT, YMB, YMI, MEA, PDA. The best fungi-growth of S. crispa is shown within the 0.2% addition of multi-mineral. The slow fungi-growth of S. crispa is shown within as the opposite. The phisical growth of S. crispa has a absolute need of comparatably large amount of P,K,N,S etc as inorganic minerals. In addition of that, as a minor element, Fe, Zn, Cu, Mo, Co, Mn, Cl etc are should be included. The best fungi-growth of S. crispa is shown within the 0.1% addition of biotin. The slow fungi-growth of S. crispa is shown within as the opposite. The best fungi-growth of S. crispa is shown within the 2% addition of fructose. The slow fungi-growth of S. crispa is shown within as the opposite.

• Journal of environmental and Sanitary engineering
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• v.23 no.3
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• pp.59-71
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• 2008

In this study, we intend to present the uncontrolled landfill maintenance plans by diversely reviewing the operating conditions of landfill and environmental effects and economical issues resulted from the operation of landfill for the purpose of suggesting the optimal maintenance plans applicable to the uncontrolled landfill and unused landfill located in Korea. We perform the basic and precise surveys against three landfill sites showing the biggest problem out of 8 unsanitary landfills sites located in Y County. We compare and review the treatment plans prepared and operated by the N Landfill. The compared and reviewed results show that the local stabilization plan is more effective than the excavation and transfer treatment plan when considering the economic efficiency only. However, the excavation and transfer treatment plan is valid when considering the diverse elements. The G Landfill is operated with separated into living waste landfill section and construction waste landfill section. However, some landfill gas collection bores or holes are installed in its living waste landfill section, which has not been used for about 20 years, as a part of follow-up control. The element causing the environmental damage is considerably reduced in its living waste landfill section. However, the effort to keep the follow-up control through the local stabilization work is required. The landfill is under processing in the construction waste landfill section. However, most of buried wastes are the inorganic wastes such as waste materials and concrete, so the maintenance plan focused on the use of top land by installing the local stabilization facilities is considered as an effective plan. The landfill is under processing in the K Landfill. It seems to be difficult to maintain this landfill through the local stabilization. The excavation and transfer treatment plan to completely remove the potential environmental pollution source is considered as the valid plan.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.6
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• pp.808-820
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• 2006

In regard to indoor air quality patterns, the government introduced various polices that were about managing and monitoring quality of indoor air as a major assignment, and also executed 'Indoor Air Quality Management Act' which was presented in the May, 2004. However, among the multi-usage facilities controlled by the Act, the school was not included yet. This study goal was to investigate PM 10 pollution patterns of the high school classrooms using a pattern recognition method based on cluster analysis and disjoint principal component analysis, and further to survey levels of inorganic elements in May, June, and September, 2004. A hierarchical clustering method was examined to obtain possible objects in pseudo homogeneous sample classes by transformation raw data and by applying various distance. Following the analysis, the disjoint principal component analysis was used to define homogeneous sample class after deleting outliers. Then three homogeneous Patterns were obtained as follows: the first class had been separated and objects in the class were considered to be sampled under semi-open condition. This class had high concentration of Ca, Fe, Mg, K, Al, and Na which are related with a soil and a chalk compounds. The second class was obtained in which objects were sampled while working air-conditioners and was identified low concentration of PM 10 and elements. Objects in the last class were assigned during rainy day. A chalk, soil element and various types of anthropogenic sources including combustions and industrial influenced the third class. This methodology was thought to be helpful enough to classify indoor air quality patterns and indoor environmental categories when controlling an indoor air quality.

• Korean Journal of Plant Resources
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• v.24 no.1
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• pp.89-97
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• 2011

Shallot is a foreign crop introduced from France in 1995 as a new overwintering field crop with an aim to develop as an export crop. This study was conducted to investigate the effect of nitrogen fertilization level and time of supplementary nitrogen fertilization on growth and development of shallot, and to suggest to several problems raised during introductory trial cultivations. Optimum amount of nitrogen fertilization for bulb yield was 24 kg per 10 a. The best time of supplementary fertilization was February and March, with an equal amount in each month. The inorganic element composition of the harvested bulbs was not significantly affected by N fertilization level or by time of supplementary nitrogen fertilization.

• Korean Journal of Medicinal Crop Science
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• v.28 no.2
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• pp.119-127
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• 2020

Background: The aim of this study was done to identify whether mass produced wild ginseng culture broth prepared from cultivated wild ginseng roots could have an application in enhancing the agricultural utility value of leafy vegetables. Methods and Results: Leafy vegetables Lactuca sativa and Brassica juncea were treated with wild ginseng culture broth. Plants were examined and treatment (100 ㎖) applied twice a week over an eight week period. Total phenolic and flavonoid content of treated plants was then measured. Wild ginseng culture broth treatment resulted in phenolic and flavonoid content of 0.40 mg·GAE/㎖ and 0.36 mg·QE/㎖, respectively in L. sativa. When treated with wild ginseng culture broth, free radical scavenging ability was found to be higher in both L. sativa and B. juncea whereas antimicrobial activity was found to be higher in B. juncea (625 ㎍/㎖) than in L. sativa. Inorganic element analysis of L. sativa and B. juncea showed that Ca and Mg were higher in the wild ginseng broth treatment group, whereas harmful elements such as As were reduced. Conclusions: Rather than discarding the wild ginseng culture broth, it can be used as a fresh biomaterial by reprocessing it as agricultural products that can promote growth and improve functionality in plants.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.3
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• pp.173-179
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• 2004

In this study, the influence of heat treatment and Ca contents on the electrochemical behavior was investigated. Mg-Ca alloys, i.e., Mg-0.22wt%Ca, Mg-0.56wt%Ca, Mg-1.31wt%Ca are prepared by ingot metallurgy. As-cast Mg-Ca alloys exhibited better electrochemical properties than pure Mg. Especially, Mg-0.22wt%Ca alloy improves its anode efficiency up to 62% and lowers the OCP up to -1.72VSCE. Microstructure and XRD patterns of Mg-Ca alloys show that additive Ca element is mainly solid-solutioned. While, the others show the microstructure and XRD pattern with large $Mg_2Ca$ at grain boundary. To assess the effect of heat treatment on the as-cast Mg-alloy, the specimens were heat treated at $200^{\circ}C$ for 2 hours under $CO_2$ gas atmosphere. Although corrosion properties of Mg-Ca alloys are somewhat deteriorated by heat treatment at $200^{\circ}C$ Mg-0.22wt%Ca alloy with uniformly distributed nano-sized $Mg_2Ca$ phase in ${\alpha}$-Mg matrix show still better corrosion properties than pure Mg specimen.

• Korean Journal of Materials Research
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• v.32 no.11
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• pp.508-514
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• 2022

Piezoelectric composite films which are enabled by inorganic piezoelectric nanomaterials-embedded polymer, have attracted enormous attention as a sustainable power source for low powered electronics, because of their ease of fabrication and flexible nature. However, the absorption of applied stress by the soft polymeric matrices is a major issue that must be solved to expand the fields of piezoelectric composite applications. Herein, a flexible and porous piezoelectric composite (piezoelectric sponge) comprised of BaTiO₃ nanoparticles and polydimethylsiloxane was developed using template method to enhance the energy conversion efficiency by minimizing the stress that vanishes into the polymer matrix. In the porous structure, effective stress transfer can occur between the piezoelectric active materials in compression mode due to direct contact between the ceramic particles embedded in the pore-polymer interface. The piezoelectric sponge with 30 wt% of BaTiO₃ particles generated an open-circuit voltage of ~12 V and a short-circuit current of ~150 nA. A finite element method-based simulation was conducted to theoretically back up that the piezoelectric output performance was effectively improved by introducing the sponge structure. Furthermore, to demonstrate the feasibility of pressure detecting applications using the BaTiO₃ particles-embedded piezoelectric sponge, the composite was arranged in a 3 × 3 array and integrated into a single pressure sensor. The fabricated sensor array successfully detected the shape of the applied pressure. This work can provide a cost-effective, biocompatible, and structural strategy for realizing piezoelectric composite-based energy harvesters and self-powered sensors with improved energy conversion efficiency.

• Journal of the Korea Institute of Building Construction
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• v.22 no.1
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• pp.1-10
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• 2022

Recently, due to the frequent occurrence of localized torrential rains and heat waves caused by abnormal climates. For this reason, it is necessary to develop an economical and eco-friendly rainwater detention facility that can secure the groundwater level through rainwater detention as well as flood prevention against concentrated rainfall by simultaneously implementing rainwater permeation and storage. In this study, the structural safety of an eco-friendly rainwater infiltration type detention facility made using eco-friendly inorganic binders including red clay was examined. Static analysis considering the constant load and additional vertical load and dynamic analysis considering the seismic spectrum were performed. As a result, it was found that the eco-friendly prefabricated rainwater infiltration type detention facility developed in this study has a maximum stress of about 68.1% to 75.4% and a maximum displacement of about 0.9% to 9.6% under the same load and seismic conditions compared to the existing PE block rainwater detention facility. It was confirmed that the eco-friendly prefabricated rainwater infiltration type detention facility secured excellent structural stability.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.206-217
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• 1982

This experiment was conducted to study about nutrient absorption of flag leaf and chaff of rice plant different transplanting date with elevations. Heading stage was delayed by destructive cold temperature or late transplanting. Plant analyses revealed that above poor plants also had higher total nitrogen content, but ower silicate in the flag leaf and sterile chaff. Total nitrogen and silica contents to accumulated in flag leaf between yield was significant high correlation. The chaff of late transplanting and sterility was high total nitrogen. Relationship between silicate absorption and total nitrogen of chaff was significant high correlation. Ripening temperature after heading stage was influenced total nitrogen of chaff. Phosphate, potassium, calssium and silicate contents of chaff increased hight ripening temperature but total nitrogen decreased. Therefore, inorganic element contents of chaff was closely connected with grain sterility.