• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.1
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• pp.64-75
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• 2009

The shipbuilder's requirement for a higher power output rating has led to the development of a super large two stroke low speed diesel engines. Usually a large-sized bore engine ranging from $8{\sim}14$ cylinders, this engine group is capable of delivering power output of more than 100,000 bhp at maximum continuous rating(mcr). Other positive aspects of this engine type include higher thermal efficiency, reliability, durability and mobility. This plays a vital role in meeting the propulsion requirement of vessels, specifically for large container ships, of which speed is a primary concern to become more competitive. Consequently, this also resulted in the modification of engine parameters and new component designs to meet the consequential higher mean effective pressure and higher maximum combustion pressure. Even though the fundamental excitation mechanisms unchanged, torsional vibration stresses in the propulsion shafting are subsequently perceived to be higher. As such, one important viewpoint in the initial engine design is the resulting vibration characteristic expected to prevail on the propulsion shafting system(PSS). This paper investigated the torsional vibration characteristics of these super large engines. For the two node torsional vibration with a nodal point on the crankshaft, a tuning damper is necessary to reduce the torsional stresses on the crankshaft. Hence, the tuning torsional vibration damper design and compatibility to the shafting system was similarly reviewed and analyzed.

• Journal of Korean Elementary Science Education
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• v.43 no.1
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• pp.136-147
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• 2024

It has recently be emphasized in science education that lessons that can develop "scientific participation and action" should be implemented to scientifically recognize various problems and respond to them as well as risks that occur in real life. This study aims to analyze the characteristics of scientific participation and action lessons as perceived by the preservice primary school teachers. To do that, the researchers collected and analyzed the lesson plans designed by the preservice teachers based on the achievement standard related to noise for grades 3-4 in 2022 revised science curriculum. Focusing on the stages of "problem recognition," "data collection and analysis," and "implementation and sharing," the results identity the four main characteristics as problem-solving activity, inquiry activity, investigative activity, and activity that encourages practical actions. The two or three features were found to be combinated in a lesson depending on its context. In some cases, only one feature was seen in a lesson. Based on the results, educational implications were discussed in terms of the teaching and learning methods and teacher education for implementing scientific participation and action.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.2
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• pp.208-217
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• 2001

Model-based color image halftoning method using dot-pattern database is proposed for low-resolution color image printing. Dot-pattern database used in the proposed method is based on Blue-Noise Mask. The database consists of dot-patterns constructed by circular dot-overlap model according to each color value. In halftoning procedure, input color value is reproduced as the dot-pattern selected to minimize the difference between the color values of the original image and those of the printed image. Also, the contrast sensitivity function as a human visual model is used to improve the perceived quality of the printed image in dot-pattern selection. Thus, the proposed method can substantially reproduce the color values of the pixels in original image and obtain better image quality. In the experiment, the proposed method has less ΔΕ/Sub ab/ between the original image in monitor and the printed one than that of ED and BNM halftoning. This result approves that the proposed method reproduces better image quality.

• Journal of Korean Academy of Nursing
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• v.25 no.1
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• pp.124-140
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• 1995

Cardiac cathererization has become a routine diagnostic procedure indicated for evaluation of a wide varity of cardiac conditions. Patients are admitted to the coronary care unit after cardiac catheterization. These conscious patients report feeling uncomfortable in the CCU, but no studies have been done on the effects of bed rest, sand bags on the femoral puncture site and restricted mobility for 4 to 12 hours or longer postprocedure. The main objective of this thesis is to provide basic data to nursing on interventions which de-crease the uncomfortableness experienced by patients in the CCU following cardiac catheterization. In this phenomenological study, the various discomforts felt by the patients were collected and classified. The study subjects were a convenience sample of 29 patients who were admitted to the CCU of a general hospital in Inchon following cardiac catheterization. They were conscious, so they were able to communicate without difficulty. The data were collected over an U days period from July 21, to October 14, 1994. The subjects were interviewed using unstructured open questions and the interviews were tape recorded with the patient's permission The data were analyzed using the Van Kaams phenomenological method. Reliability and validity were exammed by two professor of nursing science, one head nurse, one staff nurse and one cardiologist. The results of the study are summarized as follows ; 1. The 129 descriptive statements by the postcardiac catheterization patients of discomfort were organized into 19 themes. 2. The 19 themes were divided into 3 categories ; physical, psychological, and environmental aspects. 3. The problems concerning the physical aspect were the discomfort of restriction of movement, dysuria, medical devices, pain in the puncture site, symptom is related to the procedure of cardiac catheterization, headache and dizziness, leg painand tingling sensation, and chest pain. The problems concerning the psychological aspect were regret resulting from dependency, economic burden, dissatisfaction with medical personnel, dissatisfaction with medical service system, anxiety about the result of the procedure, concern about the prognosis, loneliness, and concern over treatment procedure. The problems concerning the environmental aspect were influence from neighboring patients, noise, and maladaptation to environmental change. The necessity for holistic care which satisfies physical, psychological, and environmental need must be emphasized in order to solve these discomforts.

• Journal of Korean Society of Transportation
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• v.25 no.6
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• pp.89-97
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• 2007

The car-dependent traffic system based on highly advanced industrialization and economic growth causes various urban problems including traffic jams, energy consumption, air pollution, noise, car accidents and other issues. Particularly in urban areas, air pollution from motor vehicles is worse than pollution from past industrialization. In this study, therefore, the authors grasped car exhaust reduction effects by using microsimulation and those traffic policies that could make cars flow smoothly, reducing the air pollution in urban areas through analysis on profitability. As a result, the weekday-based car using system has been found most effective as it does not need investment cost. However, this system may be socially unacceptable, as it requires the government to change driver behavior. Therefore, the government needs to first reach a consensus with the citizens regarding this system. This system will also be effective with other alternatives. As a follow-up study, the authors will research citizens' perceived impacts of car exhaust on air pollution through a study on preference and grasp the possibility of applying these study results to real traffic policies.

• Journal of the Korea Convergence Society
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• v.11 no.6
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• pp.311-318
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• 2020

This was a basic study to ascertain the changes in sleep patterns and the factors disrupting sleep in hospitalized children. The participants were children aged 6 years or younger who had been hospitalized in an advanced general hospital in a particular region. A total of 81 participants were included, and for data analysis using SPSS/WIN 21.0. The results showed that children's sleep duration decreased significantly after hospitalization compared to before (p<.001), and there were significant differences in sleep onset latency (p<.001) and frequency of sleep deprivation (p<.001). Factors perceived by the children's mothers to disrupt sleep included the child's health state, noise in the ward, nurses' treatments, and lighting in the ward. This study verified that children's sleep quality and duration decreases during hospitalization, demonstrating the need to prepare measures to improve sleep in hospitalized children based on an understanding of changes in sleep patterns and disrupting factors.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.6
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• pp.1241-1248
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• 2019

In this paper, an auxiliary device was implemented to help blind people more safely from obstacles or risk factors while walking. The ultrasonic sensors detect obstacles in the front, so that the noise gap and the vibration intensity of the buzzer can be heard differently by distance and angle, and so the situation can be perceived by pedestrians. When the ambient light becomes darker than the light intensity set using the CdS resistance value of the light sensor, the LED automatically turns on, makes it easier for pedestrians to recognize the position of the auxiliary device through buzzer if the pedestrian misses the aid using the gyro sensor's slope. Moreover, the location and situation of the blind were transmitted to the caregiver to check safety and behavior using GPS and Bluetooth.

• Journal of the Korean Society for information Management
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• v.33 no.4
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• pp.77-101
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• 2016

Recently, attention has been drawn to a new form of a public library, that is, a public library in a complex facility constructed in the same building or site with another facility. To get active users' or local governments' supports in the public library in a complex facility, it is necessary to build library strategic plans based on the analysis of users' evaluation and demands. Thus, this study analyzed the user satisfaction and perception of the 28 public libraries in complex facilities in Seoul. As a result, it was found that most users overall satisfied with public libraries in complex facilities in terms of human resources, information resources, and the links among services and positively perceived their environments and services. In order to provide more satisfaction to the users in public libraries in complex facilities first, it is necessary to improve the accessibility of libraries, to secure the sufficient library space, to prevent the outside noise, to link the facilities which bring mutual synergistic effect, and to develop a program and service accompanying other facilities.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.210-216
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• 2013

It is hard to listen to the music clearly in the presence of background noise. In this paper, a method that modifies the audio signal automatically to enhance the audio listening experience in adverse environment is proposed. Specifically, the method that amplifies the audio signal so that the perceived loudness of audio signal in each band becomes similar to that of the noiseless signal. The loudness perception model proposed by Moore et. al is utilized. Extending the previous work that is applied to speech reinforcement, the full band signal sampled at 48kHz is manipulated based on the loudness restoration principle. Moreover, based on the observation that the audio clarity is compromised even with loudness restored signal, a modification that intentionally boosts high frequency loudness more than lower band is also proposed. Experimental results showed that the proposed algorithm can enhance the audio listening experience in adverse environment.

• Journal of KSNVE
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• v.9 no.3
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• pp.613-620
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• 1999

Brake judder{or cold judder) caused by the disc thickness variation(DTV) is investigated experimentally, This cold judder is often perceived by steering wheel vibration, brake pedal pulsation, and vehicle body vibration. In this paper, how the DTV profile affects the vibration characteristics of vehicle body is shown by order tracking analysis(OTA) and operational vibration analysis(OVA) The tri-axial vibrations are measured at the knuckle, lower rm, and the body side of the lower arm. Also, measured are the wheel speed and the detail DTV profile. The interpretations of OTA results in three directions of tested vehicle indicate the relative importance in the contribution of the run-out and the DTV to the judder vibration. Also, the OVA results show the prominent vibration amplitude of the lower arm in the direction of the vehicle movement. in which the second order of wheel speed is dominant. These results could be used to diagnose the judder problem and to establish the correction methods.