• Transactions of Materials Processing
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• v.27 no.6
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• pp.379-385
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• 2018

This study investigated the effect of extrusion conditions on microstructures and mechanical properties of AM80 magnesium alloys. The billets of magnesium alloy used for hot extrusion were prepared by permanent mold casting method, and its extrusion was hot direct extrusion with different extrusion conditions. The results of microstructural analysis showed that the main phases in the as-casted alloys were ${\alpha}-Mg$, ${\beta}-Mg_{17}Al_{12}$, and lamella $Mg_{17}Al_{12}$. Hot extrusion results, The tensile strength of the most soundly manufactured extruded bars (extrusion temp: $350^{\circ}C$, extrusion ratio: 27:1, ram speed: 2mm/s) was approximately 327MPa at room temperature. The increase in the mechanical properties of hot-extruded alloys was as a result of grain refinement by dynamical recrystallization during hot extrusion.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.2
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• pp.66-73
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• 2022

Partial-hardened hot stamping has been well known to be very effective to absorb more energy in automotive lateral crash. Hardness distribution and dimensional change after partial-hardened hot stamping have been studied to find out effect of thermal deformation of the heated hot stamping die on dimensional accuracy of automotive center pillar. Soft zone of commercial center pillar showed 275~345 in Vickers hardness, indicating bigger non-uniformity which resulted from thermal deformation of heated die. Dimensional changes in soft zone of the commercial center pillar measured by three dimensional scanner were much bigger than that in hard zone. It has been found that hot stamping die compensation considering thermal deformation in soft zone causes a significant decrease in hardness deviation in the soft zone, corresponding to 20 percent of commercial center pillar and subsequently leads to much higher dimensional accuracy.

• Korean Journal of Psychosomatic Medicine
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• v.25 no.2
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• pp.176-184
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• 2017

Objectives : Middle aged women with depression often experience hot flush symptoms. It is still unclear about the association between depression and hot flush symptoms. Therefore, we investigated hormonal profile, functional somatic symptoms, coping styles and attitude for menopause between depressed women with hot flush and those without hot flush. Methods : This study included 33 depressed patients with hot flush symptoms and 33 depressed patients without hot flush symptoms. Hot flush was confirmed through prospective daily symptom ratings for a week. Subjects' coping styles were assessed by the stress coping checklist. Somatic symptoms were assessed by the Patient Health Questionnaire-15(PHQ-15). Sex hormonal levels were assayed by a radioimmunoassay. The Brief World Health Organization Quality of Life Assessment Instrument(WHOQOL-BREF) was used to evaluate quality of life. Results : In coping style, depressed women with hot flush symptoms used less 'problem-centered coping'($13.15{\pm}3.17$) and 'search for social support'($11.83{\pm}2.84$) than those without hot flush symptoms($15.17{\pm}3.1$, p=0.028 ; $14.25{\pm}3.22$, p=0.009 ; respectively). Depressed women with hot flush symptoms showed more negative attitude toward post-menopause, but its statistical significance was marginally insufficient(p=0.059). We did not find any group differences in sex hormonal levels and somatic complaints assessed by the PHQ-15. The score of social relationship domain of WHOQOL-BREF was significantly lower in subjects with hot flush symptoms($8.62{\pm}2.04$) than subjects without hot flush symptoms($9.71{\pm}1.65$ ; p=0.044). Conclusions : Among middle aged women with depression, the manifestation of hot flush symptoms was associated with coping styles and attitude for menopausal transition. Hot flush symptoms in depressed women negatively influence quality of life, so clinicians actively perform therapeutic approach in case of depressed patients with hot flush symptoms. In case of depressed patients who present hot flushes, cognitive behavior therapy or stress management might be an effective treatment option in company with antidepressants or hormonal treatment. Later, longitudinal study will be needed to evaluate risk factor, cause and effect associated with hot flush and depression.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.25-32
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• 2009

Currently, various types of TDM (Transportation Demand Management) policies are being studied and implemented in an attempt to overcome the limitations of supply oriented policies. In this context, this paper addressed issues of effectiveness and possible domestic implementation of the HOT lane. The possible site of implementation selected for this simulation study is part of the Kyung-bu freeway, where a dedicated bus lane is currently being operated. Minimum length of distance required in between interchanges and access points of the HOT lane for vehicles to safely enter and exit the lane, and traffic management policies for effectively managing the weaving traffic trying to enter and exit the HOT lane were presented. A 5.2km section of freeway from Ki-heuing IC to Suwon IC and a 8.3km section from Hak-uei JC to Pan-gyo JC have been selected as possible sites of implementation for the HOT lane, in which congestion occurs regularly due to the high level of travel demand. VISSIM simulation program has been used to analyze the effects of the HOT lane under the assumption that one-lane HOT lane has been put into operation in these sections and that the lane change rate were in between 5% to 30%. The results of each possible scenario have proven that overall travel speed on the general lanes have increased as well by 1.57~2.62km/h after the implementation of the HOT lane. It is meaningful that this study could serve as a basic reference data for possible follow-up studies on the HOT lane as one effective method of TDM policies. Considering that the bus travel rate would continue increase and assuming the improvement in travel speed on general lanes, similar case study can be implemented where gaps between buses on bus lane are available, as a possible alternative of efficient bus lane management policies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.1
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• pp.89-94
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• 2015

This study was conducted to compare the laser weldability of boron steel and hot-stamped steel. In general, boron steel is used in the hot-stamping process. Hot-stamping is a method for simultaneously forming and cooling boron steel in a press die after heating it to the austenitizing temperature. Hot-stamped steel has a strength of 1500 MPa or more. Thus, in this study, the laser weldability of boron steel and thet of hot-stamped steel were investigated and compared. A continuous wave disk laser was used to produce butt and lap joints. In the butt welding, the critical cooling speed at which full penetration was obtained in the hot-stamped steel was lower than that of boron steel. In the lap welding, the joint widths were similar regardless of the welding speed when full penetration was obtained.

• Nutrition Research and Practice
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• v.5 no.4
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• pp.281-287
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• 2011

In this study, we evaluated the antioxidant activity of pine needle extracts prepared with hot water, ethanol, hexane, hot water-hexane (HWH), and hot water-ethanol (HWE), using the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical method. The hot water extract possessed superior antioxidant activity than the other extracts. We also compared the antioxidant activity of pine needle extracts through ROS inhibition activity in a cellular system using MC3T3 E-1 cells. The hot water extract exhibited the lowest ROS production. The pattern of HPLC analysis of each extract indicated that the hot water extract contained the highest proanthocyanidin level. The pine needle hot-water extract was then isolated and fractionated with Sephadex LH-20 column chromatography to determine the major contributor to its antioxidant activity. The No.7 and 12 fractions had high antioxidant activities, that is, the highest contents of proanthocyanidins and catechins, respectively. These results indicate that the antioxidant activity of procyanidins from the hot water extract of pine needles is positively related to not only polymeric proanthocyanidins but also to monomeric catechins. Moreover, the antioxidant activity of the pine needle hot water extract was similar to well-known antioxidants, such as vitamin C. This suggests that pine needle proanthocyanidins and catechins might be of interest for use as alternative antioxidants.

• The Journal of Korean Obstetrics and Gynecology
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• v.20 no.4
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• pp.148-159
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• 2007

Purpose: Vasomotor symptoms including hot flash are very common to postmenopausal women. Estrogen therapy was regarded as the best option for relieving menopausal symptoms until 2002, when the Women#s Health Initiative(WHI) reported the side effect of the therapy. Consequently, studies on the complementary and alternative medical herbs and therapy for the management of menopausal symptoms have followed. And so we have reviewed some international clinical studies about the management of postmenopausal symptoms with acupuncture therapy. Methods: "Menopause and acupuncture" was designated as a key word in the search site. Pub Med, and nine papers dealing with hot flash among the relevant RCTs were selected, and then, the effect of acupuncture on hot flash and the way the researches had been done was examined. Results : The intensity of hot flash reduced significantly and the frequency of hot flash was inclined to reduce, but not significantly, compared to the controlled group. Conclusion: Each clinical test has its limitations in point of the number of the required samples. However, it still shows the possibility that acupuncture itself will be effective enough to reduce the intensity of hot flash to a certain degree. It is believed that extensive clinical tests on the effect of acupuncture on hot flash will need to be done hereafter. And when the tests are carried out, it is required to exclude placebo effect, do blind test, and carefully select and control the methods.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.743-748
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• 2005

In order to realize a three-dimensional shape on CAD, the machining process has been widely used because it offers practical advantages such as precision and versatility. However, the traditional machining process needs a large amount of time in cutting a product and the remained material causes trouble such as inconvenience for clarity. Therefore, a new rapid manufacturing process using the hot tool, Rapid Heat Ablation process (RHA), has been developed. In this paper, the hot tool for RHA process is devised to minimize radius of heat affected zone and also investigated for verification. TRIZ well-known as creative problem solving method is applied to overcome the contradictive requirements of the hot tool. For the detailed design of the hot tool, numerical model is established with several assumptions. Based on the numerical results, surface temperature is measured with K-type thermocouple at the predetermined location. Numerical and experimental results show that the devised hot tool fulfils its requirements. It verifies the practicality of hot tool that the hemisphere shape is ablated using the hot tool with stair structure.

• The Journal of Engineering Geology
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• v.26 no.4
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• pp.561-570
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• 2016

For the investigation of hydrochemical changes in hot spring waters from the Onyang hot spring area, we analyzed water chemistry of 24 hot spring waters in 2011 and 2016. The results showed that there is no significant change in temperature and properties of the hot spring waters. The relationship of 2016 between temperature and $SiO_2$ and F reveals a positive trend ($r^2=0.60$, 0.47), and the relationship between temperature and Ca, Mg, Cl, $SO_4$, $HCO_3$, EC reveals a negative trend ($r^2=0.50$, 0.11, 0.50, 0.63, 0.23, 0.51). The relationship between temperature and pH is a positive trend, while the one between temperature and DO is a negative trend, indicating that the source is from deep groundwater. When plotted on Piper diagram, most of which are $Na-HCO_3$ but several hot waters are classified as the $Na(Ca)-HCO_3$, indicating inflow of shallow groundwater was occurred.

• The Journal of Korean Medicine
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• v.29 no.4
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• pp.180-193
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• 2008

Objectives: We intended to identify factors related to the severity of hot flush of climacteric women from an East-West medical point of view. Methods: We surveyed 446 climacteric women who had received Korean oriental medical questionnaires about clinical symptom patterns and health medical examinations at Kyung-Hee University Medical Center over 1 year, from June 2007 to May 2008. Then, we compared hot flush with clinical symptom pattern and health medical examination result. Results: As the severity of hot flush increased, hypnagogic disorder in sleep pattern, abdominal gaseous distention in digestion pattern, tenesmus in evacuation pattern, yellow or reddish urine in voiding pattern, spontaneous sweating in sweating pattern, chest oppression in psychologic pattern, not-pulling-bedclothes in cold-heat pattern and mouth dryness in craniocervical symptom increased (p<0.05). In relation to digestion pattern, the severity of hot flush showed statistical significance according to prevalence of gastritis diagnosed by gastroscopy and upper GI series(p<0.01). In relation to voiding pattern, the severity of hot flush showed statistical significance according to prevalence of urine protein diagnosed by urinalysis (p<0.05). In relation to sweating, psychologic & cold-heat pattern, triiodothyronine (T3) increase and thyroid stimulating hormone (TSH) decrease were significantly correlated as the severity of hot flush increased (p<0.01). Conclusions: The result showed that hot flush of climacteric women had to be considered in respect of digestion disorder related to gastritis and sweating psychologic cold-heat disorder related to thyroid hormone.