• The Journal of the Acoustical Society of Korea
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• v.40 no.1
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• pp.46-54
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• 2021

In this paper, active noise control was performed to reduce radiated noise in the low frequency band of dishwashers. First, through an analysis of the noise environment of the dishwasher, it was confirmed that the pump noise contributed the most to the radiated noise in the low frequency band, From the result of the noise environment analysis, the reference signal was selected to be the vibration signal of the pump body. The reference signal was obtained by using the accelerometer on the pump body, which can prevent acoustic feedback. The error signal sensor was selected as a microphone located at 1 m in front of the dishwasher and 0.5 m in height. And to design the controller, the error signal and the reference signal were measured at the operational rpms of the dishwasher at 2,500 rpm, 2,600 rpm and 2,800 rpm, and the secondary path transfer function was measured. The designed controller was mounted on Digital Signal Processor (DSP) equipment, and the control performance was verified experimentally. As a result of the measurement at the 3 operational rpms, the 7th multiple component of pump operating frequency decreased by 1.93 dB, 4.43 dB, 5.15 dB per rpm, and the 12th multiple component decreased by 6.67 dB, 2.34 dB, 4.28 dB per rpm. And overall Sound Pressure Level (SPL) decreased by 0.84 dB, 2.58 dB, 1.48 dB by rpm.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.941-948
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• 2022

Disaster response robots are deployed to disaster sites where human access is difficult and dangerous. The disaster response robots explore the disaster sites prevent a structural collapse and perform lifesaving to minimize damage. It is difficult to operate robots in the disaster sites due to rough terrains where various obstacles are scattered, communication failures and invisible environments. In this paper, we developed a series connectable wheeled robot module. The series connectable wheeled robot module was developed into two types: an active driven robot module and a passive driven robot module. A wheeled robot was built by connecting the two active type robot modules and one passive type robot module. Two robot modules were connected by one DoF rotating joint, allowing the wheeled robot to avoid obstructions in a vertical direction. The wheeled robot performed driving and obstacle avoidance using only pressure sensors, which allows the wheeled robot operate in the invisible environment. An obstacle avoidance experiment was conducted to evaluate the performance of the wheeled robot consisting of two active driven wheeled robot modules and one passive driven wheeled robot module. The wheeled robot successfully avoided step-shaped obstacles with a maximum height of 80 mm in a time of 24.5 seconds using only a pressure sensors, which confirms that the wheeled robot possible to perform the driving and the obstacle avoidance in invisible environment.

• Korean Journal of Exercise Nutrition
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• v.25 no.4
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• pp.1-9
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• 2021

[Purpose] This study analyzed data from the 7^th Korean National Health and Nutrition Examination Survey (2016-2018) to compare the differences in energy intake and physical activity (PA) levels in middle-aged Korean men aged 40-59 years according to household type and the presence of metabolic syndrome (MetS). [Methods] Data from 2,266 young adults (aged >39 years and <60 years) were obtained from the KNHANES. We analyzed the differences in energy intake and PA levels according to household type and MetS. The presence or absence of MetS was determined by measuring waist circumference, blood pressure, fasting blood glucose, triglyceride, and HDL-C levels. [Results] Regarding total nutritional intake, no relationship with MetS was observed regardless of household type (interaction between MetS and household type: p = 0.875). No differences in total PA were observed between multiple- and single-person households (interaction between MetS and household type: p = 0.122). The relationship between MetS and MetS components according to nutritional intake showed that participants with a higher energy intake had a 27% lower prevalence of low high-density lipoprotein cholesterol (HDL-C) (p < 0.05) and a 36% higher prevalence of high blood pressure (p < 0.01). The relationship between MetS and MetS components according to the PA level showed significantly reduced prevalence of MetS by approximately 39%, 35%, and 43% (p < 0.01, 0.01, and 0.001) in subjects who were somewhat active, active, and very active, respectively, compared to inactivity. [Conclusion] Middle-aged men showed no difference in nutritional intake and PA between multiple- and single-person households. However, the risk of MetS was significantly higher in participants with approximately 1.5 times the energy intake compared to the group with the lowest energy intake. Moreover, higher levels of PA had a marked positive effect on the risk factors and prevalence of MetS. Therefore, we suggest that reducing the total energy intake and increasing total PA are important for preventing MetS in middle-aged men regardless of household type.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4659-4664
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• 2014

The noise produced in a factory is a cause of the noise complaint of the surrounding residential areas. In addition, it affects the work efficiency and health of workers. This paper presents the results of a basic study to reduce the noise generated from the blower, which is often used in the factory of a small and medium scale, using an active noise controller (ANC) in three-dimensional space. For this purpose, the simulator program, which can compare various parameters of the original noise and controlled noise, such as sound pressure levels, power spectra, and equivalent noise levels, was developed. The noise data was recorded at 17 points around a turbo fan blower currently being operated in a small-medium size factory. The simulation results showed that the power spectrum was reduced by a maximum of 40dB in the low frequency band and the average equivalent noise level attenuation was 12.6dB.

• Korean Journal of Community Nutrition
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• v.25 no.3
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• pp.236-245
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• 2020

Objectives: Cardiovascular disease is a major cause of death in the elderly in Korea. Increased arterial stiffness is linked to risk of cardiovascular disease and mortality. The purpose of this study was to investigate the relationship between arterial stiffness and physical activity in the elderly. Methods: A total of 209 older adults (110 men and 99 women) participated in this study. Arterial stiffness of subjects such as brachial-ankle pulse wave velocity (baPWV) and ankle brachial pressure index (ABI) was measured using a non-invasive vascular screening device (VP-1000 Plus, Omron, Kyoto, Japan). The interviewed Korean version of the international physical activity questionnaire short form (IPAQ-SF) was used to evaluate subject's physical activity level and classify subjects as active or inactive group based on the time spent doing moderate to vigorous physical activity (MVPA). Results: The mean age of total subjects was 75.3 ± 5.6 years. There was no significant difference in sex distribution between the active group (39.7%) and inactive group (60.3%). The baPWV (1,758.1 ± 375.2 cm/sec) of the active group was significantly lower than that (1,969.7 ± 372.3 cm/sec) of the inactive group (P < 0.05). There was a significant inverse association between time spent in MVPA and baPWV (r = -0.245, P < 0.01). Conclusions: This study suggests that physical activity programs for older adults are needed to prevent arteriosclerosis.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.6
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• pp.431-436
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• 2009

There are five principal causes for excessive bleeding in the immediate postextraction phase ; (1) Vascular wall alteration (wound infection, scurvy, chemicals, allergy) (2) Disorders of platelet function (genetic defect, drug-aspirin, autoimmune disease) (3) Thrombocytopenic purpuras (radiation, leukemia), (4) Inherited disorders of coagulation (hemophilia, Christmas disease, vitamin deficiency, anticoagulation drug-heparin, coumarin). If the hemorrhage from postextraction wound is unusually aggressive, and then dehydration and airway problem are occurred, the socket must be packed with gelatine sponge(Gelfoam) that was moistened with thrombin and wound closure & pressure dressing are applied. The thrombin clots fibrinogen to produce rapid hemostasis. Gelatine sponges moistened with thrombin provide effective coagulation of hemorrhage from small veins and capillaries. But, in dental alveoli, gelatine sponges may absorb oral microorganisms and cause alveolar osteitis (infection). This is a case report of bleeding control by continuous rubber strip & iodoform gauze drainage (without gelfoam packing) of active bleeding infection sites of three teeth extraction wounds in a 46-years-old female patient with advanced liver cirrhosis.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.17 no.1
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• pp.15-23
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• 2011

Background: The objective of this study was to determine the effectiveness of the pelvic compression belt (PCB) on the thickness of the transversus abdominis (TrA) during active straight leg raising (ASLR). Methods: Thirty healthy subjects (10 men and 20 women) volunteered to participate in this study. The thickness of TrA was measured using a real-time ultrasonic diagnostic imaging system. Subjects were instructed to rest in a resting (hook-lying) position and to perform ASLR with and without the PCB. The PCB was positioned below the anterior superior iliac spine with stabilizing pressure from elastic bands. Results: In the resting position and during ASLR, the thickness of the TrA significantly differed between subjects with and without PCB (p<.05). In addition, there was a significant interaction between the measurement position and the presence or absence of PCB (p<.05). Conclusions: These findings suggest that the PCB may affect deep core muscles such as TrA during various activities. Further studies are required to generalize the results of the present study.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.115-120
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• 1998

The surface chemistry of $Re_2(CO)_{10}$ deposition for preparing highly dispersed rhenium catalysts and the formation of active site for the metathesis were studied. Alumina as support was treated at 1223K(DA) and 773k(PDA), respectively. The metathesis activity of the catalysts at 298K was measured by using pure propene under atmospheric pressure. The oxidation number of rhenium on PDA was very high, and that on DA was zero-valent with highly dispersed state. The prepared Re/DA catalyst was easily activated by treating with oxygen gas at low temperatures after thermal decomposition at high temperatures. The activity of Re/DA catalyst, even with very low rhenium loading, was much higher than that of Re/PDA or conventional $Re_2O_7/Al_2O_3$ catalysts. Therefore, rhenium carbonyl was effective for preparing a highy active metathesis catalyst with very low rhenium loading. Rhenium ion on Re/DA catalyst seemed to be bonded to two oxygen atoms on DA surface, that is, two-valent. The two-valent rhenium ion was changed to about six-valent by treating with oxygen. It could be considered that propene metathesis occurred through carbene complex which was formed on the six-valent rhenium ions.

• Korean Journal of Pharmacognosy
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• v.38 no.4
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• pp.312-320
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• 2007

The screening of anti-cancer activity for the MeOH extracts of 163 natural sources, which were registered as edible plants by Korea Food & Drug Administration, exhibited 9 extracts to have significant inhibitory effects on farnesyl-protein transferase (FPTase) and phosphatase of regenerating liver-3 (PRL-3). In order to confirm the inhibitory activity of these active extracts, the activity assay was repeated for some fractions obtained from the active extracts using Medium Pressure Liquid Chromatography (MPLC). Some fractions of Carya illinoensis, Chlorella vulgaris, Panicum miliaceum, Perilla frutescens, Rosmarinus officinalis showed over 50% inhibitory activity on FPTase as well as those of Capsella bursa-pastoris, C. illinoensis, C. vulgaris, Coix lacrymajobi, Myristica fragrans, P. miliaceum, R. officinalis did over 50% inhibitory activity on PRL-3.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.3
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• pp.259-264
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• 2014

Tip vortex cavitation (TVC) is important for naval ships and research vessels that require raising the cavitation inception speed to maximum possible values. The concepts for alleviating the tip vortex are summarized by Platzer and Souders (1979), who carried out a thorough literature survey. Active control of TVC involves the injection of a polymer or water from the blade tip. The main effect of such mass injection (both water and polymer solutions) into the vortex core is an increase in the core radius, consequently delaying TVC inception. However, the location of the injection port needs to be selected with great care in order to ensure that the mass injection is effective in delaying TVC inception. In the present study, we propose a semi-active control scheme that is achieved by attaching a thread at the propeller tip. The main idea of a semi-active control is that because of its flexibility, the attached thread can be sucked into the low-pressure region closer to the vortex core center. An experimental study using a scale model was carried out in the cavitation tunnel at the Seoul National University. It was found that a flexible thread can effectively suppress the occurrence of TVC under the design condition for a model propeller.