• International Journal of Automotive Technology
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• v.7 no.7
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• pp.763-768
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• 2006

Emission reduction in the cold start period of SI engines is crucial to meet stringent emission regulations such as SULEV Emissoin reduction is the starting point of the study in the which the variable valve timing (VVT) technology may be one promising method to minimize cold start emissions while maintaining engine performance. This is because it is possible to change valve overlap and residual gas fraction during cold start and idle operations. Our previous study showed that spark timing is another important factor for reducing cold-start emissions since it affects warm-up time of close-coupled catalysts (CCC) by changing exhaust gas temperature. However, even though these factors may be favorable for reduction of emissions, they may deteriorate combustion stability in these operating conditions. This means that the two variables should be optimized for best exhaust emissions and engine stability. This study investigated the effects of valve and spark timings in idle performance such as combustion stability and exhaust emissions. Experiments showed that valve timings significantly affected engine stability and exhaust emissions, especially CO and $NO_x$, due to change in residual gas fraction within the combustion chamber. Spark timing also affects HC emissions and exhaust gas temperature. Yet it has no significant effects on combustion stability. A control strategy of proper valve timing and spark timing is suggested in order to achieve a reduction in exhaust emissions and a stable operation of the engine in a cold start and idle operation.

• Women's Health Nursing
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• v.25 no.3
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• pp.258-272
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• 2019

Purpose: The purpose of this study was to identify nursing interventions for the postpartum breast care of mothers and determine the effectiveness of interventions for breast pain and engorgement by systematic review. Methods: Eight national and international databases were reviewed to retrieve and collect randomized controlled trial and controlled clinical trial literature published up to March 2015. Two reviewers independently selected the studies and performed data abstraction and validation. The risk of bias was assessed using Cochrane criteria. A meta-analysis of the studies was performed to analyze the data. Results: The meta-analysis showed that breast massage, along with routine breast care, resulted in a 3.52-point reduction in pain on a 10-point visual analogue scale. Meta-analysis of therapy with cold cabbage leaves and routine breast care showed a pain reduction of 0.54 points. Meta-analysis of cold cabbage leaf application in the experimental group versus cold compress therapy in the comparison group showed a pain reduction of 0.44 points. Meta-analysis of cold cabbage leaf application and routine breast care showed an engorgement reduction of 0.67 points. Conclusion: The results of the analysis of 12 articles showed that hot and cold compresses, breast massage, and cabbage application were effective for postpartum breast pain and engorgement.

• Physical Therapy Rehabilitation Science
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• v.2 no.2
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• pp.75-80
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• 2013

Objective: The purpose of this study was to examine the effect of cold applied the night before or in the morning on pain and symptoms of plantar fasciitis. Design: Experimental study. Methods: Thirty subjects with plantar fasciitis were recruited for this study. Subjects with plantar fasciitis either had no intervention, cold applied (20 minutes) at night before bed, or 20 minutes in the morning upon wakening. Plantar fascia tenderness and pain were evaluated. There were ten subjects in each group. Measures included visual analog scale, plantar facial thickness via high resolution ultrasound, algometer measure, and range of motion of the ankle and foot. There were 3 groups of 10 subjects, control (no intervention), cold the night before bed, and cold in the morning before rising. Results: The greatest relief of symptoms was cold used at bedtime the night before the measurements. Cold used in the morning was not as effective as cold used in the evening before bed. Cold use reduced the thickness of the plantar fascia and irritation. There was a 13% reduction in plantar fascia thickness with cold the night before (p<0.05), a 44% reduction in pain and an 86 % increase in the force that could be applied to the bottom of the foot without pain (p<0.05). Conclusions: Cold applied for 20 minutes prior bedtime is effective for reduced symptomology caused by plantar fascia inflammation.

• International Journal of Automotive Technology
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• v.3 no.1
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• pp.41-46
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• 2002

Effect of secondary air injection (SAI) on hydrocarbon reduction has been investigated in a single cylinder Sl engine operating at cold-steady/cold-start conditions. The hydrocarbon emission and exhaust gas temperature with and without catalytic converter were compared with continuous and synchronized SAIs, which injected secondary air intermittently into exhaust port. Effects of SAI location, SAI pressure, SAI timing, and location of catalytic converter have been investigated and the results are compared for both SAls with base condition. At cold-steady condition, the rate of HC reduction increased as the location of SAI was closer to the exhaust valve for both synchronized and continuous SAls. The emission of HC decreased with increasing exhaust-A/F when it was rich, and was relatively insensitive when it was lean. The timing of SAI in synchronized SAI had significant effect on HC reduction and exhaust gas temperature and the synchronized SAI was found to be more effective in HC reduction and exhaust gas temperature compared to the continuous SAI . At cold-start condition, when the catalytic converter was located 20 cm downstream from the exhaust port exit, the catalytic converter warm-up period for both SAls decreased by about 50%, and the accumulated hydrocarbon emission during the first 120 s decreased about by 56% and 22% with the synchronized and continuous SAIs, respectively, compared to that of the base condition.

• Transactions of Materials Processing
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• v.22 no.3
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• pp.158-164
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• 2013

The spheroidization behavior of cementite in a SK85 high carbon steel was investigated in this study. Fine and coarse pearlite microstructures were obtained by appropriate heat treatments according to the TTT diagram of SK85 high carbon steel. Hot rolled plates of SK85 steel were austenitized at $800^{\circ}C$ for 2 hrs and then put directly into a salt bath at either $570^{\circ}C$ or $670^{\circ}C$ to obtain a fine pearlite (FP) structure and a coarse pearlite (CP) structure, respectively. Cold rolling was subsequently conducted on those specimens with reduction ratios from 0.2 to 0.4. Spheroidization heat treatments were conducted at the subcritical temperatures of 600 and $720^{\circ}C$ for 1 to 32 hrs to elucidate the effect of initial microstructures, heat treatment temperature, and cold reduction ratios on the cementite spheroidization rate. Spheroidization proceeded with fragmentation of cementite plates, spheroidization of the cementite platelets, and coarsening consecutively. Mechanical fragmentation of cementite by cold rolling expedited the rate of spheroidization. The spheroidization rate of FP was much more rapid than that of CP and the spheriodization rate increased with increases in the cold reduction ratio.

• Steel and Composite Structures
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• v.23 no.3
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• pp.363-383
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• 2017

In cold-formed stainless steel lipped channel-sections, use of web openings for service purposes are becoming increasingly popular. Web openings, however, result in the sections becoming more susceptible to web crippling. This paper presents a finite element investigation into the web crippling strength of cold-formed stainless steel lipped channel-sections with circular web openings under the interior-two-flange (ITF) loading condition. The cases of web openings located centred and offset to the bearing plates are considered in this study. In order to take into account the influence of the circular web openings, a parametric study involving 2,220 finite element analyses was performed, covering duplex EN1.4462, austenitic EN1.4404 and ferritic EN1.4003 stainless steel grades. From the results of the parametric study, strength reduction factor equations are proposed. The strengths obtained from reduction factor equations are first compared to the strengths calculated from the equations recently proposed for cold-formed carbon steel lipped channel-sections. It is demonstrated that the strength reduction factor equations proposed for cold-formed carbon steel are unconservative for the stainless steel grades by up to 17%. New coefficients for web crippling strength reduction factor equations are then proposed that can be applied to all three stainless steel grades.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.405-408
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• 2009

Edge cracks in cold rolling always influence to the quality of productions, while the "V" shaped cracks were propagated by passing the roll gap. We set up the sizes and shapes of initial cracks in simulation according to the references from real productions. Different to in hot rolling, the cracks in cold rolling couldn't be reduced from propagation automatically after generated, even if these could be reduced by changing the process parameters. In this paper, we described the affections of process parameters on the propagation of edge cracks, such as reduction ratio and tension. We predicted that the dependence of the cracks propagations of changing of process conditions and expected to gain the smaller edge cracks. By raising the reduction ratio, the cracks were propagated increasingly in both transverse and rolling directions. And as tension raise, the cracks became propagated in both directions in which transverse direction was less effectively.

• Journal of Acupuncture Research
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• v.23 no.1
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• pp.25-38
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• 2006

Objectives : Acupuncture has been widely used in oriental medicine. The aim of this research is to study how does the interaction between reinforcement-reduction by twirling nine and six and subject's cold or heat tendency effect on Heart Rate Variability. Methods : We divided our subjects into 3 groups at random and classified subjects by their cold or heat tendency using questionnaire for cold-heat patternization. Group 1 is acupuncture at shinmun(HT7) reinforcement group, 2 is acupuncture at shinmun(HT7) reduction group, 3 in acupuncture at hapkok(LI4) group. According to their group, we acupunctured. Before and after acupuncture Heart Rate Variability raw data were measured during 5 minutes. LF, HF, LF norm HF norm were calculated. We analyzed these data using 3-way repeated ANOVA, Paired student T-Test. Results : 3-way repeated ANOVA showed significant interaction among LF, each group and subject's cold heat tendency(p<0.05). Paired student T-Test showed significant differences between before and after acupuncture at shinmun(HT7) reinforcement method in cold tendency men and acupuncture at shinmun(HT7) reduction method in heat tendency men(p<0.05). Conclusion : These results suggest that acupuncture at Shinmun(HT7) has an effect on declining sympathetic nerve function and has an effect on stabilizing mind through Interaction between reinforcement-reduction by twirling nine and six and subject's cold or heat tendency. We propose that more prudent care is needed about subject's cold or heat tendency and acupuncture technique of reinforcement-reduction to achieve the most suitable treatment effect.

• Transactions of Materials Processing
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• v.15 no.8 s.89
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• pp.603-608
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• 2006

The main purpose of the present study has been placed on investigating the mechanical properties and microstructures of C-Si-Mn-V steels for cold forming manufactured by controlled rolling and cooling technology. The steels were manufactured in electric arc furnace (EAF) and casted to $160{\times}160mm$ billet. The billets were reheated in walking beam furnace and rolled to coil, the stocks were rolled by Controlled Rolling and Cooling Technology (CRCT), so rolled at low temperature by water spraying applied in rolling stage and acceleratly cooled before coiling. Rolled coils were cold drawed to the degree of 16%, 27% of area reduction respectively without heat treatment. Microstructual observation, tensile test, compression test and charpy impact tests were conducted. The mechanical properties of the steels were changed by area reduction of cold drawing and it is founded that there are optimum level of cold drawing to minimize compression stress for these steels. From the result of this study, it is conformed that $80kg_{f}/mm^{2},\;90kg_{f}/mm^{2}$ grade high strength microalloyed steel for cold forming are developed by accelerated cooling and optimum cold drawing.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.321-324
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• 2005

The main purpose of the present study has been placed on investigating the effects of controlled rolling and cooling on the microstructures and mechanical properties of C-Si-Mn-V steels for cold forming. The steels were manufactured in vacuum induction melting(VIM) furnace and casted to 1.1ton Ingots and the ingots were forged to $\Box150$ billet. The forged billets were reheated in walking beam furnace and rolled to coil, the stocks were rolled by Controlled Rolling and Cooling Technology (CRCT), so rolled at low temperature by water spraying applied in rolling stage and acceleratly cooled before coiling. Rolled coils were cold drawed to the degree of $27\%$ of area reduction without heat treatment. Microstructual observation, tensile test, compression test and charpy impact tests were conducted. The mechanical properties of the steels were changed by area reduction of cold drawing and it is founded that there are optimum level of cold drawing to minimize compression stress for these steels. From the result of this study, it is conformed that mechanical properties and microstructure of C-Si-Mn-V steels for cold forming were enhanced by accelerated cooling and founded optimum level of cold drawing.