• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.2
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• pp.108-115
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• 2015

Electro-mechanical actuator installed on aircraft consists of a decelerator which magnifies the torque in order to rotate an axis connected with aircraft control surface, a control section which controls the motor assembly through receiving orders from cockpit and a motor assembly which rotates the decelerator. Electro-mechanical actuator controls aircraft altitude, position, landing, takeoff, etc. It is an important part of a aircraft. Aircraft maneuvering causes vibrations to electro-mechanical actuator. Vibrations may result in structural fatigue. For that reason, it is necessary to analyze the system structural safety. In order to analyze the system structural safety. It is needed reasonable finite element model and structural response stress closed to real value. In this paper, analytic model is derived by using the simplified finite element model, and damping ratio which is closely related to response stress is derived by using modal test. So, we developed analytic model in less than 10 % error rate, compared with modal test. Vibration response stress close to real value was estimated from analytic model modified with modal experimental damping ratio. Estimation method for damping ratio with empirical formula was suggested partly. Finally, It was proved that electro-mechanical actuator had reasonable structure margin of safety at environmental random $3{\sigma}$ stress during life cycle.

• Structural Engineering and Mechanics
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• v.42 no.2
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• pp.153-174
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• 2012

Micromechanical facture models can be used to predict ductile fracture in steel structures. In order to calibrate the parameters in the micromechanical models for the largely used Q345 steel in China, uniaxial tensile tests, smooth notched tensile tests, cyclic notched bar tests, scanning electron microscope tests and finite element analyses were conducted in this paper. The test specimens were made from base metal, deposit metal and heat affected zone of Q345 steel to investigate crack initiation in welded steel connections. The calibrated parameters for the three different locations of Q345 steel were compared with that of the other seven varieties of structural steels. It indicates that the toughness index parameters in the stress modified critical strain (SMCS) model and the void growth model (VGM) are connected with ductility of the material but have no correlation with the yield strength, ultimate strength or the ratio of ultimate strength to yield strength. While the damage degraded parameters in the degraded significant plastic strain (DSPS) model and the cyclic void growth model (CVGM) and the characteristic length parameter are irrelevant with any properties of the material. The results of this paper can be applied to predict ductile fracture in welded steel connections.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.11
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• pp.92-97
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• 2010

The object of this study is to investigate the definite method for pitting damaged surfaces. Pitting is a sort of fatigue damages and it is made by a repetitive load. For a judgment between damages or not, sensing vibrations of test equipment is simple. However, it is not only difficult to observe a growth of pitting but also impossible to detect the juncture of initial pitting. Therefore, a method for the pitting damaged area measuring technique was effectively implemented by Two Roller Machine. The change of surface damaged area was measured by an optical microscope in regular time and calculated by the use of dark and bright ratio of test specimens' pictures taken by optical microscope. In conclusion, S - N Curves gained by Failure rate - Cycle graph was led and the curves are able to be chosen as occasion demands for a failure area percentage.

• Steel and Composite Structures
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• v.23 no.5
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• pp.571-583
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• 2017

A kind of accordion-web RBS connection, "Tubular Web RBS (TW-RBS)" connection is proposed in this research. TW-RBS is made by replacing a part of web with a tube at the desirable location of the beam plastic hinge. This paper presents first a numerical study under cyclic load using ABAQUS finite element software. A test specimen is used for calibration and comparison of numerical results. Obtained results indicated that TW-RBS would reduce contribution of the beam web to the whole moment strength and creates a ductile fuse far from components of the beam-to-column connection. Besides, TW-RBS connection can increase story drift capacity up to 9% in the case of shallow beams which is much more than those stipulated by the current seismic codes. Furthermore, the tubular web like corrugated sheet can improve both the out-of-plane stiffness of the beam longitudinal axis and the flange stability condition due to the smaller width to thickness ratio of the beam flange in the plastic hinge region. Thus, the tubular web in the plastic hinge region improves lateral-torsional buckling stability of the beam as just local buckling of the beam flange at the center of the reduced section was observed during the tests. Also change of direction of strain in arc shape of the tubular web section is smaller than the accordion webs with sharp corners therefore the tubular web provides a better condition in terms of low-cycle fatigue than other accordion web with sharp corners.

• Korean Journal of Community Nutrition
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• v.18 no.6
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• pp.577-587
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• 2013

This study aimed to elicit the variability of appetite and food intake patterns in female college students during different menstrual phases. The craving for certain foods and physiological and psychological symptoms of menstrual phase (pre- and post-menstrual) were investigated by self-administered questionnaire. Three hundred and sixty six students who were 20.9 years old and had $19.8kg/m^2$ of BMI volunteered to participate in this study. Most of the subjects (89.5%) experienced the premenstrual syndrome (PMS) such as irritation, bodily fatigue, nervosity. Symptoms such as tiredness, stomachache, changes in taste and increased appetite were pointed out to be experienced at the onset of the menstrual cycle. The variability of food intake in premenstrual phase, 11.0% of subjects had decreased food intake where as 68.8% had experienced increased intake. The postmenstrual phase, 20.1% had decreased food intake while 45.2% had experienced increased intake due to changes in the appetite. Before starting menstruation, most of the subjects craved for sweets. The group who had experienced abnormal appetite during menstrual phase was significantly high ratio in overweight and obese students (p<0.05). We also observed an association between the PMS score and the variability of eating patterns during the menstrual phase. The students who experienced changing appetite and food intake had significantly high PMS score in the premenstrual phase (p<0.01) and postmenstrual phase (p<0.05). These results suggested a need for future study related to changes in the actual nutrient intake and activity level during the menstrual phase.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.2
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• pp.463-467
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• 2012

Purpose: To assess the safety and efficacy of a gemcitabine plus docetaxel regimen as a second line therapy for patients with advanced soft tissue sarcoma (STS) resistant to doxorubicin and ifosfamide-based therapy. Patients and Methods: Medical records of 64 patients with advanced STS who received gemcitabine plus docetaxel regimen as a second line treatment between May 2006 and June 2011 were examined. All patients had been previously treated with doxorubicin plus ifosfamide-based regimen at first line setting. Patients received gemcitabine 900 $mg/m^2$ on days one and eight intravenously over 90 minutes, followed by docetaxel 75 $mg/m^2$ on day eight intravenously over one hour. Cycles were repeated every 3 weeks. Results: The male-to-female ratio was 37/27 and the median age was 44 years (range; 19-67 years). Objective responses were observed in 13 (20.3 %) patients (2 CR, 11 PR) and stable disease in 21 (32.8 %). Total clinical benefit (CR+PR+SD) was observed in 34 (53.1 %). Median overall survival (OS) was 18 months (95% confidence interval (CI):12.1-23.9) and Median time to progression (TTP) was 4.8 months (95% CI: 3.6-6). A total of 243 cycles of chemotherapy were administered. The median number of cycle was 3 (range;1-11). The most common grade 3-4 hematologic toxicity was neutropenia (35.9 %). The most common nonhematologic toxicities consisted of nausea/vomiting (37.5 %), mucositis (32.8 %), peripheral neuropathy (29.7%), and fatigue (26 %). There was no toxicity-related death. Conclusion: The combination of gemcitabine plus docetaxel is an active and tolerable regimen as a second line therapy for patients with advanced soft tissue sarcoma who have failed doxorubicin and ifosfamide-based therapy.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.17 no.2
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• pp.69-76
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• 2017

Citrin deficiency is an autosomal recessive disorder caused by mutations in the SLC25A13 gene on chromosome 7q21.3, and a type of urea cycle disorder that causes hyperammonemia. Although neonatal intrahepatic cholestasis and adult-onset type II citrullinemia, a type of citrin deficiency, have been described well in many articles for several decades, failure to thrive and dyslipidemia caused by citrin deficiency (FTTDCD), the other type of citrin deficiency, has been only identified recently. There was previously no case report about FTTDCD in Korea. Patients with FTTDCD could present with loss of appetite, fatigue, failure to thrive, hypoglycemia, hypercitrullinemia, dyslipidemia, and an increased lactate/pyruvate ratio. Routine evaluation may not reveal the cause of hypoglycemia caused by citrin deficiency. We recently had a case that presented with recurrent hypoglycemia in a 30-month-old boy. Chemistry profiling, urine organic acid analysis, plasma acylcarnitine analysis, and hormone studies indicated values within the normal range or non-specific findings. Mutation analysis to identify the cause of hypoglycemia identified the subject as a compound heterozygote carrying each of the c.852_855del ($p.Met285Profs^*2$), and c.1177+1G>A mutant alleles. We report here on this unusual case of citrin deficiency presenting with FTTDCD for the first time in Korea.

• Journal of Korean Society of Steel Construction
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• v.23 no.4
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• pp.503-514
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• 2011

In this research, the seismic connection details for two concrete-filled U-shape steel beam-to-H columns were proposed and cyclically tested under a full-scale cruciform configuration. The key connecting components included the U-shape steel section (450 and 550 mm deep for specimens A and B, respectively), a concrete floor slab with a ribbed deck (165 mm deep for both specimens), welded couplers and rebars for negative moment transfer, and shear studs for full composite action and strengthening plates. Considering the unique constructional nature of the proposed connection, the critical limit states, such as the weld fracture, anchorage failure of the welded coupler, local buckling, concrete crushing, and rebar buckling, were carefully addressed in the specimen design. The test results showed that the connection details and design methods proposed in this study can well control the critical limit states mentioned above. Especially, the proposed connection according to the strengthening strategy successfully pushed the plastic hinge to the tip of the strengthened zone, as intended in the design, and was very effective in protecting the more vulnerable beam-to-column welded joint. The maximum story drift capacities of 6.0 and 6.8% radians were achieved in specimens A and B, respectively, thus far exceeding the minimumlimit of 4% radians required of special moment frames. Low-cycle fatigue fracture across the beam bottom flange at a 6% drift level was the final failure mode of specimen A. Specimen B failed through the fracture of the top splice plate of the bolted splice at a very high drift ratio of 8.0% radian.