• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.247-258
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• 2008

Environmental standards for beneficial uses of dredged materials are proposed. Even though chemical analysis of ocean sediments are carried out frequently, their analyses results were not interrelated with the effects of biological lives due to a shortage of biological data. These facts have resulted in difficulty to develope Korean's standards of recycling dredged materials. This paper first searched existing current foreign standards, analyzed local contaminated ocean sediment data, identified their main chemical components of contaminants, and then compared with clean-up standards of sediments consisting of lower and higher levels. From these analysis, new environmental standards considering Korean domestic circumstances are proposed. It is judged that new standards are appropriate to both Korean national sedimental environments and economically recycling aspects because environmental standard levels proposed are higher than background levels of sediments in Korean and foreign standards.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.4016-4027
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• 2014

Understanding network latency is important for providing consistent and acceptable levels of services in network-based applications. However, due to the difficulty of estimating applications' network demands and the difficulty of network latency modeling the management of network resources has often been ignored. We expect that, since network latency repeats cycles of congested states, a systematic classification method for network status would be helpful to simplify issues in network resource managements. This paper presents a simple empirical method to classify network status with a real operational network. By observing oscillating behavior of end-to-end latency we determine networks' status in run time. Five typical network statuses are defined based on a long-term stability and a short-term burstiness. By investigating prediction accuracies of several simple numerical models we show the effectiveness of the network status classification. Experimental results show that around 80% reduction in prediction errors depending on network status.

• Journal of the Ergonomics Society of Korea
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• v.29 no.6
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• pp.943-949
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• 2010

When PCB soldering is performed with microscope due to the electronic components' microminiaturization, workers' awkward upper body postures and difficulties being in focus among lens, object and eyes are one of reasons for productivity decline. The object of this study is to investigate the level of difficulties of work and the extent of productivity improvement by changing work interfaces from the work using microscope to the work using LCD monitor. Independent variables was usage of microscope and image system and dependent variables were upper body segments including neck, shoulder, back, and waist, task convenience and eye fatigue. The Visual Analogue Scale (10cm) was used for questionnaire and one way ANOVA (two levels) and two sample t-test were conducted. In addition, RULA rating was conducted for working postures. The result showed that interface changes of LCD monitor, suggested by productivity comparison per one Man Hour, highly contributed to work convenience and productivity improvement.

• Journal of Acupuncture Research
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• v.20 no.1
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• pp.1-12
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• 2003

Objectives : The purpose of this study is to compare Xingjian(LR2) Shaofu(HT8) with Dadun(LR1) Shaofu(HT8) on Blood Pressure in Hypertensive RAT induced by Two Kidney One Clip(2KIC). Methods : This experiments was to investigate the effects of LR2 HT8(originated from ${\ll}$Classic on Difficulty${\gg}$ Shi Ze Xie Qi Zi), LR1 HT8(originated from ${\ll}$Ling Shu${\gg}$ Sheng Ze Xie Zhi) acupuncture on the blood pressure, cardiomegalic index, and plasma levels of atrial natriuretic peptide in hypertensive rat induced by 2K1C. Results: 1. Blood pressure was decreased significantly after third acupuncture of LR2 HT8. 2. Blood pressure was decreased significantly after acupuncture of LR2 HT8, but was increased after LR2 HT8. 3. Cardiomegalic index was not changed after acupuncture of LR2-HT8 and LR1-HT8 4. Plasma levels of atrial natriuretic peptide was increased significantly after acupuncture of LR2 HT8 but LR1 HT8 was not changed.

• Korean Journal of Environment and Ecology
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• v.29 no.4
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• pp.626-635
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• 2015

Recently, the number of trail users in Korea has risen tremendously. Consequently, the cost of safety measures related to hiking is sharply increasing. Despite the safety cost input, the number of heart-related adverse events has been not decreasing. Therefore, this research aims to suggest the use of objective and quantitative trail use information in terms of course difficulty. The study site is Jirisan Dullegil (Jirisan Forest Trail). The currently available trail difficulty information either provides the difficulty rating in terms of 3 to 5 levels according to several empirical difficulty factors reported by staff who maintain the forest or simply states the distance of each trail. Thus, many trail visitors feel a great gap between the given information and actual difficulties they experience. In this study, we tried to assess the degree of difficulty by actual energy consumption. Calculating the volumetric oxygen consumption (VOC) by the distance and gradient not only makes possible an absolute rating but a comparison among the trails as well. Also, it is highly effective to simply describe the exercise intensity of a certain trail. Further, it is easy to check the VOCs' changes by switching the start-end points of the same trail. Providing the trail information of VOCs by sections and directions, we expect to prevent heart-related accidents.

• 중국학논총
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• no.63
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• pp.121-136
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• 2019

Graded reading is to match reading competency of readers with difficulty levels of text, based on the study of readability. This article discusses how to apply new media to develop Chinese graded reading materials which are more interesting, scientific and practical than traditional paper materials. The graded materials on the new media platform can be used for Chinese second language learners to self-study, and also for instructors to support reading and writing instruction in class or after class.

• The Journal of the Acoustical Society of Korea
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• v.42 no.6
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• pp.617-626
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• 2023

This study aims to investigate the preferred sound level of water sound for various levels of open-plan-office noise regarding soundscape quality and speech privacy. And assessment of the work efficiency of the water sound. For the laboratory experiment, office noise was recorded using a binaural microphone in a real open-plan office. For the assessment of the soundscape quality and speech privacy, Overall Soundscape Quality (OSQ) and Listening Difficulty (LD) were evaluated under three different sound levels (55 dBA, 60 dBA, and 65 dBA) and five different signal-to-noise ratios (SNR -10 dB, -5 dB, 0 dB, +5 dB, and +10 dB). After the evaluation, the preferred SNR was proposed according to OSQ and LD. For the assessment of to work efficiency of water sound, this study evaluated the cognitive performance of both of the condition noise only and combine the water sound with office noise. The results showed that LD increased as the water sound level increased, but OSQ decreased. When the water sound level was more than the office noise level, the OSQ decreased from noise only. Therefore, considering OSQ and LD, the preferred SNR of water sound was -5 dB for all noise levels. At the preferred level of water sound, the cognitive performance results were shown to decrease at 55 dBA compared to noise only, but at 60 dBA and 65 dBA combine the water sound results were increased than the noise only.

• Journal of the Korean Home Economics Association
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• v.38 no.7
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• pp.103-116
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• 2000

The purpose of this study was to find out the psychological characteristics of the unemployed, and their children's negative emotions and behavioral changes in the context of the increasing family dysfunction caused by the IMF economic crisis. The subjects were 184 public labor workers in Busan. They answered the questions about the psychological characteristics of themselves and their children, and their children's behavioral changes. Frequency analysis, $\chi$$^2$ test and logistic regression were used for data analyses. The results were as follows. The unemployed showed high levels of negative emotions and perceived their social supports as low. As well, they interpreted their quality of life as poor. They perceived their economic difficulty as high and the perception was influenced by negative emotions as well as the economic situation. Children of the unemployed showed middle levels of negative emotions, and positive and negative behavioral changes. These changes were influenced by their parent's psychological characteristics. In light of these results, psychological counseling services from social welfare centers are needed to be more actively supporting the families of the unemployed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.128-132
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• 2008

The noise levels and individual employee noise exposure levels within a factory will determine the need for hearing conservation program. The difficulty in not having an effective hearing conservation program is the risk of hearing loss that employees may sustain. In the last few years the claims for hearing loss compensation have grown due to class action litigation brought against the employer and companies that have equipment in the factory alleged to have caused hearing loss. The Blower in the factory generates the noise of 98.3dB(A) in the frequency range of 2,000Hz, which may cause occupational hearing loss. By designing close type enclosures which are made of absorption material, about 24.4dB(A) reduction has been in the factory. It is demonstrated that this kind of enclosures can be effectively used to reduce the noise in the factory.

• Journal of The Korean Association For Science Education
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• v.5 no.1
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• pp.11-17
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• 1985

This study had its objective to indentify the basic biological concepts as recommended by scholars in biology and by high school biology teachers for inclussion in the high school biology curriculum and to determine the importance levels of the concepts. The scholars for this study were selected to insure that their majors are evenly distributed across the biological areas. The final concept list contains 137 biological concepts along with their importance level judged by the scholars and high school biology teachers. The biological concepts are categorized into 12 biological areas. This study suggests that the concepts in the final list can not refect the conceptual hierarchy or inclusiveness, goals or objectives of biology education in the high school, and difficulty levels of the concepts. This study also claims that the concept list like the one produced by this study should be successively' checked and revised due to the continuous development of biological knowledge system and the constant change in the meanings of the knowledge system.