• Korean Chemical Engineering Research
• /
• v.61 no.1
• /
• pp.19-25
• /
• 2023

Although a lot of research and development has been conducted on the performance improvement of PEM (Proton Exchange Membrane) water electrolysis, the research on durability is still in early stage. This study investigated effect of temperature on the water electrolysis durability when driving temperature of the PEM water electrolysis was increased to improve performance. Voltage change, I-V, CV (Cyclic Voltammetry), LSV (Linear Sweep Voltammetry), Impedance, and FER (Fluoride Emission Rate) were measured while driving under a constant current condition in a temperature range of 50~80 ℃. As the operating temperature increased, the degradation rate increased. At 50~65 ℃, the degradation of the IrO₂ electrocatalyst mainly affected the durability of the PEM water electrolysis cell. At 80 ℃, the polymer membrane and electrode degradation proceeded similarly, and the short resistance decreased to 1.0 kΩ·cm² or less, and the performance decreased to about 1/3 of the initial stage after 144 hours of operation due to the shorting phenomenon.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.4
• /
• pp.37-45
• /
• 2010

Salt cementation, a typical naturally-cemented phenomenon, may occur due to water evaporation under the change of climate. Capillary force may influence the distribution of cement in granular soils. This study addresses the effect of capillary force on salt cementation using five different techniques: cone penetration test, electrical conductivity measurement, photographic imaging technique, nondestructive imaging technique, and process monitoring by elastic wave. Glass beads modeling a particulate media was mixed with salt water and then dried in an oven to create the cementation condition. Experimental results show that salt cementation highly concentrates at the top of the small particle size specimens and at the middle or the bottom of the large particle specimens. The predicted capillary heights are similar to the locations of high salt concentration in the cemented specimens. Five suggested methods show that the behavior of salt-cemented granular media heavily depends on the capillary force.

• Journal of the Korean Society for Heat Treatment
• /
• v.36 no.3
• /
• pp.128-136
• /
• 2023

In this study, the effects of heat treatment on the nano-scale creep behavior of CoCrFeMnNi high-entropy alloy (HEA) processed by high-pressure torsion (HPT) was investigated through nanoindentation technique. Nanoindentation experiments with a Berkovich indenter were performed on HPT-processed alloy subjected to heat treatment at 450℃, revealing that the hardness of the HPT-processed alloy (HPT sample) significantly increased with the heat treatment time. The heat treatment-induced microstructural change in HPT-processed alloy was analyzed using transmission electron microscopy, which showed the nano-sized Cr-, NiMn-, and FeCo-rich phases were formed in the HPT-processed alloy subjected to 10 hours of heat treatment (HPT+10A sample). To compare the creep behavior of HPT and HPT+10A samples, constant load nanoindentation creep experiments were performed using spherical indentation indenters with two different radii. It was revealed that the predominant mechanism for creep highly depended on the applied stress level. At low stress level, both HPT and HPT+10A samples were dominated by Coble creep. At high stress level, however, the mechanism transformed to dislocation creep for HPT sample, but continued to be Coble creep for HPT+10A sample, leading to higher creep resistance in the HPT+10A sample.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.59 no.1
• /
• pp.44-54
• /
• 2023

In this study, the second-order Nomoto's nonlinear expansion model was implemented as a Tagaki-Sugeno fuzzy model based on the heading angular velocity to design the automatic steering system of a ship considering nonlinear elements. A Tagaki-Sugeno fuzzy PID controller was designed using the applied fuzzy membership functions from the Tagaki-Sugeno fuzzy model. The linear models and fuzzy membership functions of each operating point of a given nonlinear expansion model were simultaneously tuned using a genetic algorithm. It was confirmed that the implemented Tagaki-Sugeno fuzzy model could accurately describe the given nonlinear expansion model through the Zig-Zag experiment. The optimal parameters of the sub-PID controller for each operating point of the Tagaki-Sugeno fuzzy model were searched using a genetic algorithm. The evaluation function for searching the optimal parameters considered the route extension due to course deviation and the resistance component of the ship by steering. By adding a penalty function to the evaluation function, the performance of the automatic steering system of the ship could be evaluated to track the set course without overshooting when changing the course. It was confirmed that the sub-PID controller for each operating point followed the set course to minimize the evaluation function without overshoot when changing the course. The outputs of the tuned sub-PID controllers were combined in a weighted average method using the membership functions of the Tagaki-Sugeno fuzzy model. The proposed Tagaki-Sugeno fuzzy PID controller was applied to the second-order Nomoto's nonlinear expansion model. As a result of examining the transient response characteristics for the set course change, it was confirmed that the set course tracking was satisfactorily performed.

• The Korean Journal of Franchise Management
• /
• v.3 no.2
• /
• pp.79-102
• /
• 2012

The last year, the government restricted a new store open and businness hours of a large-scale stores, discount store and super super market(ssm). So, this research was examined the effect that the retailer was affected and its correspondence strategy First this research examined how the government restricted a large-scale stores in 2009 earlier and then this research analyzed how the Japan and France restricted it. Second this research examined that a new establishment and business hours change of a large-scale stores. Bacause of a small trader resistance in 2009 latter. Finally it analyzed the effect that a retail industry was affected in the future. bacause law was enforced. On the basis these things, a victim remedy was presented by retailers view. Bacause of international law and an excess regulation. Also, this research suggest that large retailer should expand a overse market and increase retailers private brand component ratio and develop overse brand. Finally this research also suggest that trader and retailer should continue to coperate and turn business direction into franchise system.

• Structural Engineering and Mechanics
• /
• v.84 no.4
• /
• pp.547-560
• /
• 2022

By presetting various reinforcement diameters in topology optimization with the discrete model finite element analysis, an algorithm of bidirectional evolutionary structural optimization of multi-level reinforcement diameter is presented to obtain the optimal reinforcement topologies which describe the degree of stress of different parts. The results of a comparative study on different reinforcement feasible domain demonstrate that the more angle types of reinforcement are arranged in the initial domain, the higher utilization rate of reinforcement of the optimal topology becomes. According to the nonlinear finite element analysis of some deep beam examples, the ones designed with the optimization results have a certain advantage in ultimate bearing capacity, although their failure modes are greatly affected by the reinforcement feasible domain. Furthermore, the bearing capacity can be improved when constructional reinforcements are added in the subsequent design. However the adding would change the relative magnitude of the bearing capacity between the normal and inclined section, or the relative magnitude between the flexural and shear capacity within the inclined section, which affects the failure modes of components. Meanwhile, the adding would reduce the deformation capacity of the components as well. It is suggested that the inclined reinforcement and the constructional reinforcement should be added properly to ensure a desired ductile failure mode for components.

• Korean Journal of Exercise Nutrition
• /
• v.13 no.3
• /
• pp.179-184
• /
• 2009

The purpose of this study was to evaluate a exercise combined with nutritional education for improving metabolic risk factor and dietary intakes in obese middle aged women. 35 obese (body mass index of at least ≥ 25 kg/m² or %body fat ≥ 30%) middle aged women were recruited from public health center. For intervention participants, their height, weight, percentage of body fat, waist circumference, blood pressure, lipid profiles, insulin resistance index, and nutrition intakes were measured at before and after post the intervention. And change of the total energy intakes per week was measured during intervention. The subjects underwent a 12 weeks educational program including nutritional education one day per week and, aerobic exercise 3 days per week (walking). After 12 weeks exercise program combined with nutritional education, body weight (p=0.002), percentage of body fat (p<0.001), BMI (p<0.001), waist circumference (p<0.001), WHR (p=0.004), TC (p=0.004), AI (p=0.006), DBP (p=0.010), MAP (p=0.013), glucose (p=0.018), insulin (p=0.003), HOMA-IR (p<0.001) were significantly decreased and cardiorespiratory fitness was significantly (p<0.001) increased. And energy intake was significantly (p<0.001) decreased and nutritional intake and intake-style were improved through 12 weeks exercise program combined with nutritional education.

• Korean Journal of Exercise Nutrition
• /
• v.13 no.1
• /
• pp.37-44
• /
• 2009

The purpose of this study was to investigate the change of bone metabolic parameters between climbing exercise training and treadmill running training with alpha lipoic acid supplementation in ovariectomized rats. Fifty-six Sparague-Dawley, 8 weeks of age, were assigned into nine groups: normal control at pre-test (Pre-NC), normal control at post-test (NC), sham-sedentary (SS), ovariectomized-control (OVX-Con), ovariectomized-ALA inject (OVX-ALA), ovariectomized-climbing exercise (OVX-CE), ovariectomized-ALA inject+climbing exercise (OVX-ACE), ovariectomized-treadmill exercise (OVX-TE) and ovariectomized-ALA inject+treadmill exercise (OVX-ATE). The climbing exercise group voluntarily climbed the 200 cm tower to drinking water from the bottle set at the top of it. The treadmill exercise group was performed the 60 min treadmill running with grade 6-8%, and velocity 10-15 m/min. The frequency of exercise training was performed 6 days per wk in both training intervention. For the comparison of bone metabolic responses following to different training intervention, the strength, length and weight of femur, total bone density, bone mineral contents, deoxypyridioline, osteocalcin and parathyroid hormone, estradiol and lutenizing hormone were measured in this study. The body weight was higher in the OVX-Con, OVX-ALA and OVX-TE groups as compared to NC group. The total bone mineral density of OVX-ACE showed a higher value than SS, OVX-Con, OVX-ATE and OVX-TE. But urine and blood metabolic parameters showed no significance among groups. In conclusion, this study results suggested that climbing exercise training and alpha lipoic acid supplementation may an effective intervention for prevention of osteoporosis in ovriectomized rats.

• Journal of English Language & Literature
• /
• v.58 no.6
• /
• pp.1041-1061
• /
• 2012

In the late nineteenth century, British colonial activities became aggressive and annexationist in the tropics, including the Southeast Asian Archipelago, which reflected the historical circumstances of both increasing resistance from the indigenous and severe competition among European powers. Interestingly, the change in English colonial policy toward an annexationist or imperialist vision adopted the motto of a civilizing mission, which was founded on the anthropological assumption that the white English were civilized, while the non-white indigenous were savage. The assumption developed into colonial discourse through systematic gathering of anthropological knowledge about the peripheries of the Empire. The knowledge system was flawed, which stressed the differences of the peripheral populations from the English and served as an inverted discourse on the Imperial Self rather than the description of the Other. Furthermore, the natives were heterogeneous, which rendered indistinct the racial and cultural differences between the English and the natives. Still, the aboriginals called Malays, who were comprised of many ethnic subgroups, needed to be deemed savage or inferior by the English in order to justify the English civilizing work or imperial ambition. Put differently, the representation of the English as civilized necessitated the (mis)representation of the natives as savage. In this context, Clifford's works contribute to systematic misrepresentation of the Malays, on which colonial discourse is founded, though not without self-contradiction. On the other hand, Conrad's novels that are set in the Malay Archipelago resort to a strategic misrepresentation that reveals the relativity of the discourse. Exploring the dilemma of denationalization to various degrees, Conrad's Malay texts problematize the (mis)representation of the indigenous as inferior, which is the basis of English claim to superiority.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.13-13
• /
• 2022

Recently, stable crop production is threatened by the effects of climate change. In particular, it is difficult to consistently maintain agricultural policies due to large price fluctuations depending on the difference in total domestic rice production from year to year. For stable rice production amid changes in the crop growing environment, development of varieties with improved disease resistance and abiotic stress stability is becoming more important. In here, drought and cold tolerant trait have been studied. First, for the development of drought tolerant varieties, we analyzed which agricultural traits are mainly affected by domestic drought conditions. As a result, it was observed that drought caused by the lack of water during transplanting season inhibits the development of the number of tiller and reduces the yield. 'Samgang' was selected as a useful genetic resource with strong drought tolerant and stable tiller number development even under drought conditions by phenotype screening. Three of drought tolerant QTLs were identified using doubled haploid (DH) population derived from a cross between Nacdong and Samgang, a drought sensitive and a tolerant, respectively. Among these QTLs, when qVDT2 and qVDTl1 were integrated, it was investigated that the tiller number development was relatively stable in the rainfed paddy field conditions. It is known that the high-yielding Tongil-type cultivars are severely affected by cold stress throughout the entire growth stage. In this study, we established conditions that can test the cold tolerance phenotype with alternate temperature to treat low temperatures in indoor growth conditions similar to those in field conditions at seedling stage. Three cold tolerant QTLs were explored using population derived from a cross between Hanareum2 (cold sensitive variety, Tongil-type) and Unkwang (cold tolerant variety, Japonica). Among these QTLs, qSCT12 showed strong cold tolerant phenotype, and when all of three QTLs were integrated, it was investigated that cold tolerant score was relatively similar to its donor parent, Unkwang, in our experimental conditions. We are performing that development of new variety with improved cold tolerant through the introduction of these QTLs.