• Applied Chemistry for Engineering
• /
• v.18 no.5
• /
• pp.407-414
• /
• 2007

Using the MPI (Moldflow Plastics Insight) software from Moldflow Co., the optimum conditions for producing the upper part of the automobile air cleaner were obtained for 20% talc filled polypropylene (PP). The analysis was carried out to solve the cracking problem between upper and lower parts and the improved process was proposed using the flow balance. The comparative results between the conventional process, CASE-1, with one-pin gate and the new process (CASE-2) comprising two-pin gate system are the followings. In the case of CASE-2, the shorter filling time and reduced cycle time induced an improved production and processibility. In addition, the orientation and volumetric shrinkage are similar to those observed in the lower part, but the assembly, deformation, and physical characteristics are enhanced. The problem induced by the CASE-1 did not originate from the residual stress, but from the difference in the size of the upper part air cleaner after shrinkage. Thus, the orientation problem was expected to improve by optimizing the gate structure.

• Progress in Superconductivity and Cryogenics
• /
• v.4 no.2
• /
• pp.16-20
• /
• 2002

Bi-axially textured Ni tapes for YBCO coated conductors were Prepared by cold rolling and heat treatment of Ni Powder compacts. The Ni powder used in this study was 5 urn in particle size and 99.99 % in purity. The process of this study consists of filling of hi powder into a rubber mold, cold-isostatically Pressing and sintering of the powder compacts at 110$0^{\circ}C$ for 6h in 96 % Ar - 4 % H$_2$ atmosphere. The sintered compacts were cold rolled with a 5 % step reduction ratio into a 100 micron-thick tapes and then heat-treated at 100$0^{\circ}C$ for various time periods. The (200) texture of Ni tape was successfully developed through the recrystallization heat treatment of the cold rolled Ni tapes. At 100$0^{\circ}C$, the degree of texture of the heat-treated Ni tapes seems not to be significantly affected by the heat-treatment time. The short heat treatment of S min was sufficient to develop the complete (200) cube texture. The degree of in-Plane and out-of-plane texture of the prepared Ni tapes was 8-10$^{\circ}$. The heat treated Ni tapes consisted of equiaxed grains with a size 50-70 microns. and the AFM sol-face roughness was as smooth as 3 nm.

• Journal of Periodontal and Implant Science
• /
• v.40 no.4
• /
• pp.180-187
• /
• 2010

Purpose: This study evaluated the spontaneous healing capacity of surgically produced cranial defects in rabbits with different healing periods in order to determine the critical size defect (CSD) of the rabbit cranium. Methods: Thirty-two New Zealand white rabbits were used in this study. Defects of three sizes (6, 8, and 11 mm) were created in each of 16 randomly selected rabbits, and 15-mm defects were created individually in another 16 rabbits. The defects were analyzed using radiography, histologic analysis, and histometric analysis after the animal was sacrificed at 2, 4, 8, or 12 weeks postoperatively. Four samples were analyzed for each size of defect and each healing period. Results: The radiographic findings indicated that defect filling gradually increased over time and that smaller defects were covered with a greater amount of radiopaque substance. Bony islands were observed at 8 weeks at the center of the defect in both histologic sections and radiographs. Histometrical values show that it was impossible to determine the precise CSD of the rabbit cranium. However, the innate healing capacity that originates from the defect margin was found to be constant regardless of the defect size. Conclusions: The results obtained for the spontaneous healing capacity of rabbit cranial defects over time and the underlying factors may provide useful guidelines for the development of a rabbit cranial model for in vivo investigations of new bone materials.

• Journal of Korean Academy of Nursing
• /
• v.47 no.3
• /
• pp.367-379
• /
• 2017

Purpose: This study aimed to understand and describe the caring experiences of spouses of elderly people with dementia. Methods: The hermeneutic phenomenological method was used and participants were 12 spouses aged 65 and over who were taking care of their husbands or wives with dementia at home. Data were collected from individual in-depth interviews on participants' actual caring experiences. Additionally, novels, movies, and memoirs on elderly couples with partner who had dementia were included as data for the analysis. The qualitative data analysis software program was used to manage and process the collected qualitative data. Data were analyzed using hermeneutic phenomenological analysis based on four fundamental existentials including lived body, lived space, lived time, and lived others. Results: Five essential themes emerged from the analysis: 1) body moving like an old machine, 2) swamp of despair filling with hope, 3) sweet time after bitterness, 4) disappointed elderly couple in the empty nest, and 5) unappreciation vs. empathetic feelings. These essential themes were comprehensively summarized as "the road leading to the maturation of life with dedication and hope while bearing the weight of caring based on the couple's relationship." Conclusion: The findings indicate that the nature of the caring experience of spouses of elderly individuals with dementia is filled with many dynamic and paradoxical dimensions. Thus, results of the study would help with developing interventions tailored specifically for elderly spouse caregivers to support their role adaptation and ultimately improving their quality of life.

• Journal of Korean Society on Water Environment
• /
• v.24 no.4
• /
• pp.436-441
• /
• 2008

This work experimentally determined the effect of operating parameters such as temperature and solid retention time (SRT) on the phosphorus removal of municipal wastewater with waste-tire media. The experiments were carried out in pilot-scale moving bed biofilm reactor filled at a 0.15 filling ratio with the media. Total phosphorus (TP) removal efficiency was $91{\pm}5$, $75{\pm}16$, and $59{\pm}14%$ at the temperature of 9~10, 10~20, and $20{\sim}26^{\circ}C$, respectively. TP removal efficiency was $71{\pm}17$, $74{\pm}16$, $74{\pm}16$, and $68{\pm}18%$ at the SRT of 3.5~5, 5~10, 10~15, and 15~20 days, respectively. At the nitrate concentration of 1~3, 3~6, and 6~9 mg/L, TP removal efficiency was $82{\pm}9$, $68{\pm}18$, $47{\pm}7%$, respectively. The concentration of total phosphorus in the effluent was $0.1{\sim}1.8(0.8{\pm}0.4)mg/L$ regardless of operating conditions, which meets Korean phosphorus limit value, 2 mg/L, for discharge into receiving waters.

• Journal of the Korean Society for Railway
• /
• v.18 no.4
• /
• pp.301-308
• /
• 2015

To reduce the weight of a railroad vehicle, a bogie frame skin is considered for manufacture using an RTM process and composite material. Compared to other processes, RTM has merits in that it demands only simple manufacturing facilities and can produce a large and complex structure in a short cycle time. On the other hand, it is important to determine the proper number and locations of gates and vents to prevent void formation inside a structure. In this study, we numerically predicted the flow pattern in a bogie frame skin during the RTM process by distinguishing the permeability of a fiber mat as isotropic or anisotropic. Using the results, we analyzed the RTM process conditions of the bogie frame to predict skin void formation, mold filling time, and optimum location of vents depending on the permeability conditions.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.20 no.4
• /
• pp.39-54
• /
• 2017

Between 1998 and 2010, the computerization of underground facilities was completed in 84 cities. Since 2011, new pipelines have been laid or existing pipelines have been maintained, renovated, and renewed. To measure the exact location and depth of the exposure pipe, a map of underground facilities was created before filling the ground. This method is based on the time when the underground facilities of the National Geographic Information Institute Regulation No. 134 of the National Geographic Information Office revised in 2010 were drafted. The process of the drone taking the video is based on a theoretical basis of ground control points. The method works by removing all ground control points located outside of the error range and re-processing it for calculating the best result. Furthermore, using a drone-based spontaneous measuring method allows workers to obtain a high accuracy underground facilities map in error bound. The proposed method could be used as a new way to standardize the processing.

• Journal of the Mineralogical Society of Korea
• /
• v.10 no.1
• /
• pp.33-44
• /
• 1997

The reaction path of water-gneiss in 200m borehole at the Soorichi site of Yugu Myeon, Chungnam was simulated by the EQ3NR/EQ6 program. Mineral composition of borehole core and fracture-filling minerals, and chemical composition of groundwater was published by authors. In this study, chemical evolution of groundwater and formation of secondary minerals in water-gneiss system was modelled on the basis of published results. The surface water was used as a starting solution for reaction. Input parameters for modelling such as mineral assemblage and their volume percent, chemical composition of mineral phases, water/rock ratio reactive surface area, dissolution rates of mineral phases were determined by experimental measurement and model fit. EQ6 modelling of the reaction path in water-gneiss system has been carried out by a flow-centered flow through open system which can be considered as a suitable option for fracture flow of groundwater. The modelling results show that reaction time of 133 years is required to reach equilibrium state in water-gneiss system, and evolution of present groundwater will continue to pH 9.45 and higher na ion concentration. The secondary minerals formed from equeous phase are kaolinite, smectite, saponite, muscovite, mesolite, celadonite, microcline and calcite with uincreasing time. Modeling results are comparatively well fitted to pH and chemical composition of borehole groudwater, secondary minerals identified and tritium age of groundwater. The EQ6 modelling results are dependent on reliability of input parameters: water-rock ratio, effective reaction surface area and dissolution rates of mineral phases, which are difficult parameters to be measured.

• Korean Journal of Materials Research
• /
• v.15 no.9
• /
• pp.589-593
• /
• 2005

Nanoimprinting lithography (NIL) is known as a suitable technique for fabricating nano and micro structures of high definition. Hot embossing is one of NIL techniques and can imprint on thin films and bulk polymers. Key issues of hot embossing are time and expense needed to produce a stamp withstanding a high temperature and pressure. Fabrication of a metal stamp such as an electroplated nickel is cost intensive and time consuming. A ceramic stamp made by silicon is easy to break when the pressure is applied. In this paper, a plastic stamp using a high temperature epoxy was fabricated and tested. The plastic stamp was relatively inexpensive, rapid to produce and durable enough to withstanding multiple hot embossing cycles. The merits of low viscosity epoxy solutions were a fast degassing and a rapid filling the microstructures. The hot embossing process with plastic stamp was performed on PMMA substrates. The hot embossing was conducted at 12.6 bar, $120^{\circ}C$ and 10 minutes. An imprinted PMMA wafer was almost same value of the plastic stamp after 10 times embossing. Entire fabrication process from silicon master to plastic stamp was completed within 12 hours.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.12
• /
• pp.1043-1050
• /
• 2014

An air-core vortex is generated during draining after stirring a rotating cylindrical tank or after filling it with water. The formation of the air-core vortex and the time of its formation are dependent on drain conditions such as the dimensions of the tank, the initial rotation or stirring speed, and the shape of the drain port. In this study, a draining process using a two-stage drain port was numerically investigated. The length and radius of the first drain stage located in the lower part of the drain port were kept constant, whereas the radius of the second drain stage was varied for simulating the draining process. The simulation was conducted by considering an axisymmetric swirling flow for all cases. The declining water level was monitored by an interface capturing method. Further, the effects of the radius of the second drain stage on the time of formation of the air-core vortex and the internal flow structure were investigated.