• Structural Engineering and Mechanics
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• v.62 no.1
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• pp.55-64
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• 2017

An effective design approach for Multiple Tuned Mass Dampers (MTMDs) in pedestrian bridges was proposed by utilizing the transfer function to obtain each TMD's optimum stiffness and damping. A systematic simulation of pedestrian excitations was described. The motion equation of a typical MTMD system attached to a Multi-degree-of-freedom (MDOF) system was presented, and the transfer function from the input pedestrian excitations to the output acceleration responses was defined. By solving the minimum norm of the transfer function, the parameters of the MTMD which resulted in the minimum overall responses can be obtained. Two applications of lightly damped pedestrian bridges attached with MTMD showed that MTMDs designed through this method can significantly reduce the structural responses when subjected to pedestrian excitations, and the vibration control effects were better than the MTMD when it was considered as being composed of equal number and mass ratios of TMDs designed by classical Den Hartog method.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.2
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• pp.24-32
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• 1994

This paper is the experimental study on the vibration reduction of the 4WD vehicle through the change of the engine mounting conditions.(4 stroke diesel engine) The engine mounting conditions are changed to reduce the transmitted vibrations of the engine to the frame at the idle speed. Under the assumption that the Powertrain(Engine Transmission and Transfer Case) is a rigid body, the inertia properties of the powertrain are obtained by experimental modal analysis. And then the changed mounting conditions are studied by the decoupled vibration theory and analytical model of six degree of freedom. Though the mounting conditions are changed to improve the vibration isolation at idle speed, the vibration and the interior noise of the vehicle are reduced significantly at driving speed as well as idle speed. From the indirect endurance test of the front engine mounts, the changed mounting conditions are desirable to endurance as well as vibration reduction of the 4WD vehicle.

• Environmental Engineering Research
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• v.25 no.2
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• pp.197-204
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• 2020

A number of different nanoscale zero-valent iron (nZVI) materials have been prepared and compared depending on the desired properties for the particular application, but different physicochemical properties of this prepared nZVI make it difficult to universally compare and standardize them to the same scale. In this study, we aimed to demonstrate a simple microplate-based colorimetric assay using 4-chlorophenol as an indicator with respect to the remediation of real treatment targets, such as trichloroethylene (TCE), 1,1,1-trichloroethane (TCA), and atrazine. Effect of nickel contents on 4-chlorophenol reduction was successfully investigated by the miniaturized colorimetric assay. In the same manner, the effect of nickel contents on dehalogenation of TCE, TCA, and atrazine was investigated and the pseudo-first-order kinetic constants were compared with the results for 4-chlorophenol. The similar pattern could be observed between 4-chlorophenol reduction obtained by colorimetric assay and TCE, TCA, atrazine reduction obtained by a traditional chromatographic method. The reaction kinetics does not match perfectly, but the degree of reaction can be estimated. Therefore, the colorimetric assay can be a useful and simple screening tool to determine nZVI reactivity toward halogenated organics before it is applied to a particular remediation site.

• Wind and Structures
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• v.22 no.1
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• pp.17-41
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• 2016

To address the uncertainty of the flight trajectories caused by the turbulence and gustiness of the wind field over the roof and in the wake of a building, a 3-D probabilistic trajectory model of flat-type wind-borne debris is developed in this study. The core of this methodology is a 6 degree-of-freedom deterministic model, derived from the governing equations of motion of the debris, and a Monte Carlo simulation engine used to account for the uncertainty resulting from vertical and lateral gust wind velocity components. The influence of several parameters, including initial wind speed, time step, gust sampling frequency, number of Monte Carlo simulations, and the extreme gust factor, on the accuracy of the proposed model is examined. For the purpose of validation and calibration, the simulated results from the 3-D probabilistic trajectory model are compared against the available wind tunnel test data. Results show that the maximum relative error between the simulated and wind tunnel test results of the average longitudinal position is about 20%, implying that the probabilistic model provides a reliable and effective means to predict the 3-D flight of the plate-type wind-borne debris.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.7
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• pp.832-838
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• 2003

IMO NOx levels are generally possible to meet by means of primary on-engine measures. Nevertheless further significant follow-on reductions are likely to require a secondary after-treatment technique. SCR system is currently the only available technology proven at full scale to meet the 90% NOx reduction levels. Accordingly, maybe the use of an SCR system on board ship provides the solution to minimize this primary pollutant without increasing fuel consumption. In order to develop a practical SCR system for marine application on board ship, a primary SCR system using urea was made. The SCR system was set up on the ship. employed a two-stroke diesel engine as a main propulsion. which is a training ship in KMU (Korea Maritime Univ.). The purpose of this paper is to report the results about the basic effects of the above system parameters which is investigated from practical application through its trial use. The degree of NOx removal depends on some parameters. such as the amount of urea solution added, space velocity. reaction gas temperature and activity of catalyst. The preliminary results from trial run are presented.

• Korean Security Journal
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• no.51
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• pp.199-219
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• 2017

This research examined the degree to which open-street closed-circuit television (CCTV) systems reduced crime in the vicinity of elementary schools. Information including crime dates, locations, and types around nine elementary schools in the city of Chuncheon in South Korea where the cameras had been installed was gathered and assessed. By employing the Poisson regression with "month" as the unit of analysis and controlling for the days in each month, the average monthly temperatures, and crime trends, the research results show that the CCTV installations had an impact on the reduction of total crime and serious crime. However, the same reduction effect was not observed for disorder crime. Therefore, the results of this study suggest that the employing CCTV is an effective way to control overall crime rates, especially serious crime.

• Journal of Korean Medicine Rehabilitation
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• v.19 no.2
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• pp.275-287
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• 2009

Objectives : In order to observe clinical effects, carboxytherapy and electroacupuncture, we analyzed relation effect and patients' character, and researched correlation among reduction of BFM(Body Fat Mass), WHR(Waist-Hip Ratio) and AC(Arm Circumference). Methods : Among outpatients who had admitted to department of oriental rehabilitation medicine, Dae-Jeon oriental medicine hospital, Dae-Jeon university from January to September, 2008 for obesity treatment and abdominal fat, 44 subjects were chosen and carboxytherapy and electroacupuncture were practiced concurrently. Results : 1. The group under the concurrent practice of carboxytherapy and electroacupuncture showed significant decrease in BFM, BFR(Body Fat Rate), WHR and AC. 2. The group under the concurrent practice of carboxytherapy and electroacupuncture did not show statistical significance but showed decrease in BFM, WHR. The degree of decrease was proportional to that of obesity. 3. As AC decreased, BFM, WHR reduction tended to increase as well in the group under the concurrent practice of carboxytherapy and electroacupuncture. 4. Compared to the group under the sole practice of electroacupuncture, the group under the concurrent practice of carboxytherapy and electroacupuncture showed less change in BFM reduction and greater change in WHR reduction. Conclusions : From the above results, the concurrent practice of carboxytherapy and electroacupuncture had an effect on obesity and reducing abdominal fat, but did not show statistically significant decrease compare to the sole practice of electroacupuncture.

• The Journal of the Korea Contents Association
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• v.18 no.9
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• pp.273-283
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• 2018

The purpose of this study is to examine the degree of cooperation of the spouse perceived by the mother of a handicapped child on parenting stress and find out if there is a mediating effect of parenting efficacy between the degree of cooperation of the spouse and parenting stress. For such a purpose, this study surveyed 145 mothers of handicapped children who are using the day care center exclusive for handicapped children and analyzed their responses. The results show that, firstly, the degree of cooperation of the spouse perceived by the mother of a handicapped child has direct influence on the parenting efficacy. Secondly, the degree of cooperation of the spouse perceived by the mother of a handicapped child has direct influence on parenting stress. Thirdly, there is a mediating effect of parenting efficacy between the degree of cooperation of the spouse and parenting stress, which means that parenting efficacy increases as the mother perceives that she is receiving more cooperation of the spouse in the process of raising the child and the increased parenting efficacy has an influence on the reduction of parenting stress.

• Archives of Craniofacial Surgery
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• v.18 no.2
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• pp.97-104
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• 2017

Background: Nasal bone fracture is one of the most common facial bone fracture types, and the surgical results exert a strong influence on the facial contour and patient satisfaction. Preventing secondary deformity and restoring the original bone state are the major goals of surgeons managing nasal bone fracture patients. In this study, a treatment algorithm was established by applying the modified open reduction technique and postoperative care for several years. Methods: This article is a retrospective chart review of 417 patients who had been received surgical treatment from 2014 to 2015. Using prepared questionnaires and visual analogue scale, several components (postoperative nasal contour; degree of pain; minor complications like dry mouth, sleep disturbance, swallowing difficulty, conversation difficulty, and headache; and degree of patient satisfaction) were evaluated. Results: The average scores for the postoperative nasal contour given by three experts, and the degree of patient satisfaction, were within the "satisfied" (4) to "very satisfied" (5) range (4.5, 4.6, 4.5, and 4.2, respectively). The postoperative degree of pain was sufficiently low that the patients needed only the minimum dose of painkiller. The scores for the minor complications (dry mouth, sleep disturbance, swallowing difficulty, conversation difficulty, headache) were relatively low (36.4, 40.8, 65.2, 32.3, and 34 out of the maximum score of 100, respectively). Conclusion: Satisfactory results were obtained through the algorithm-oriented management of nasal bone fracture. The degree of postoperative pain and minor complications were considerably low, and the degree of satisfaction with the nasal contour was high.

• Journal of the Korean Dietetic Association
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• v.23 no.4
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• pp.374-383
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• 2017

The purpose of this study was to compare the dietary status of elderly people according to the degree of obesity and mid-arm circumference in order to provide individualized and efficient nutrition management according to the physical condition of the elderly. Among the total 328 subjects, 72.2% were female, and the mean age and body mass index of the subjects were 76.5 years and $23.4kg/m^2$, respectively. The distribution of obesity degree was 47.9% for the normal group, 23.5% for the overweight group, and 28.7% for the obesity group. The distribution of mid-arm circumference was 18.0% for the under-21 cm group, 37.2% for the 21~22 cm group, and 44.8% for the over-22 cm group. About 82.9% of the subjects were consumed at least three meals a day, and 67.8% of the subjects regularly ate alone. The responses for meal time, regular meal, and meal reduction for 3 months were highest in the 10~20 min. (43.4%), yes (79.3%), and no (58.5%) group, respectively. The responses for eating alone were significantly highest in the overweight group (97.4%), followed by the normal group and obesity group according to the degree of obesity (P<0.05). There were no significant differences in preference for five flavors according to the degree of obesity and mid-arm circumference. Among the dietary habits, 31.1% of all subjects ate milk and dairy products more than once a day, and the response for eating vegetables and fruits more than three times a day was highest in the over-22 cm group (61.9%) while the drinking rate was highest in the under-21 cm group (27.1%; P<0.05). In conclusion, the degree of obesity was related to eating ability, and mid-arm the circumference was related with fruit and vegetable consumption and drinking rate.