• Journal of the Korean Society for Railway
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• v.15 no.3
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• pp.251-256
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• 2012

Hanging sleepers are frequently observed in the ballasted track with the rail of high rigidity. These hanging sleepers at the high speed line could cause such large dynamic force compared to those at the conventional line. This dynamic force would, in turn, deteriorate train running stability as well as riding comfort, and accelerate irregularity of track and failure of track materials, leading to a sharp increase in track maintenance cost. When the wheel-rail contact spring exhibits nonlinear behavior and some components of the system like hanging sleeper exhibit bi-linear behaviors, an effective analytical method is proposed for train-track interactions. The verification of the present method is carried out comparing numerical results by the present method and those by Ono's method of RTRI.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.111-116
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• 2003

The Permanent Way consisting of rails and sleeper laid on ballast is a technically and economically viable solution. After two decades of targeted research and development activities Slab Track turned out to be a reasonable option on special fields. Slab Track proves that especially under extreme condition and loads - they reliably help stability and a long service life of track. Technical and experimental solution of slab track are particularly underlined. This paper presents a few Results of the experiments of SFRC slab tracks under fatigue load.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1318-1323
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• 2007

Proposed herein is a shape design of a different rail support block with existing ones for the commercialization of the urban maglev. The rail support for existing test lines adopts monoblock steel sleeper, whereas an individual support system has been proposed to achieve an additional cost savings and to provide an emergency exit. Also, to enhance the easiness of installation and the repairability, alignment adjusting methods suitable for the new design have been devised.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.10a
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• pp.162-167
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• 1992

The effects of railway vibration on nearby structures or equipment become severe with increasing the train speed and they may be also sufficiently intense to annoy the recipients. Often, the cost of the postcautionary measures may be more expensive than that of the precautionary ones to eliminate potential problems. This paper presents the Boundary Element approach for the evaluation of the dynamic response (in the form of the compliance matrix) of sleeper which can be used to predict the change of the vibration level.

• Journal of the Korean Society for Railway
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• v.19 no.6
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• pp.744-754
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• 2016

Asphalt concrete track (ACT) is a track system connecting wide sleepers and concrete panels on top of an asphalt concrete layer; such a system requires adequate resistance force against various longitudinal and lateral external loads. In this study, a series of experiments were carried out to assess the longitudinal and lateral resistance force of a wide sleeper and concrete panel type ACT. The required shear resistance force of the horizontal displacement restraint device (HDRD) was evaluated. Furthermore, a concrete block type anchor and a steel pipe type anchor were developed as HDRDs. The shear resistance force was decided based on the experimental results of horizontal shear tests for each anchor system. In addition, proper numbers and arrangement design guidelines for the HDRDs were suggested considering the shear resisting capacity and economics for HDRDs applied to ACT.

• Journal of Dental Anesthesia and Pain Medicine
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• v.20 no.1
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• pp.9-17
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• 2020

Background: This study aimed to compare the pain levels during anesthesia and the efficacy of the QuickSleeper intraosseous (IO) injection system and conventional inferior alveolar nerve block (IANB) in impacted mandibular third molar surgery. Methods: This prospective randomized clinical trial included 30 patients (16 women, 14 men) with bilateral symmetrical impacted mandibular third molars. Thirty subjects randomly received either the IO injection or conventional IANB at two successive appointments. A split-mouth design was used in which each patient underwent treatment of a tooth with one of the techniques and treatment of the homologous contralateral tooth with the other technique. The subjects received 1.8 mL of 2% articaine. Subjects' demographic data, pain levels during anesthesia induction, tooth extractions, and mouth opening on postoperative first, third, and seventh days were recorded. Pain assessment ratings were recorded using the 100-mm visual analog scale. The latency and duration of the anesthetic effect, complications, and operation duration were also analyzed in this study. The duration of anesthetic effect was considered using an electric pulp test and by probing the soft tissue with an explorer. Results: Thirty patients aged between 18 and 47 years (mean age, 25 years) were included in this study. The IO injection was significantly less painful with lesser soft tissue numbness and quicker onset of anesthesia and lingual mucosa anesthesia with single needle penetration than conventional IANB. Moreover, 19 out of 30 patients (63%) preferred transcortical anesthesia. Mouth opening on postoperative first day was significantly better with intraosseous injection than with conventional IANB (P = 0.013). Conclusion: The IO anesthetic system is a good alternative to IANB for extraction of the third molar with less pain during anesthesia induction and sufficient depth of anesthesia for the surgical procedure.

• Structural Engineering and Mechanics
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• v.44 no.1
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• pp.51-60
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• 2012

Concrete sleepers are essential components of the conventional railway. As support elements, sleepers are always subjective to a variety of time-dependent loads attributable to the train operations, either wheel or rail abnormalities. It has been observed that the sleepers may deteriorate due to these loads, inducing the formation of hairline cracks. There are two areas along the sleepers that are more prone to crack: the central and the rail seat sections. Several non-destructive methods have been developed to identify failures in structures. Health monitoring techniques are based on vibration responses measurements, which help engineers to identify the vibration-based damage or remotely monitor the sleeper health. In the present paper, the dynamic effects of the cracks in the vibration signatures of the railway pre-stressed concrete sleepers are investigated. The experimental modal analysis has been used to evaluate the modal bending changes in the vibration characteristics of the sleepers, differentiating between the central and the rail seat locations of the cracks. Modal parameters changes of the 'healthy' and cracked sleepers have been highlighted in terms of natural frequencies and modal damping. The paper concludes with a discussion of the most suitable failure indicator and it defines the vibration signatures of intact, central cracked and rail seat cracked sleepers.

• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.248-255
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• 2011

Impact factor of concrete and ballast track which has been used in Korea railway was applied to equation (1+0.513V/100) from AREA. As the use of this equation, overcapacity of track design might be occurred. Therefore, this study compared impact of ballast track (well, bad) and concrete track (sleeper embeded system, rail floating and sleeper floating) by field test to analyzing dynamic effect of track structure's characterstic and wheel load on service line. In addition, it suggested a method to generate reasonable impact factor on each track type.

• Journal of Oral Medicine and Pain
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• v.40 no.2
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• pp.63-71
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• 2015

Purpose: To investigate the relationship between headache and sleep by evaluating sleep quality, daytime sleepiness, and specific features related to sleep-disordered breathing (SDB). Methods: One hundred one subjects with headache and 118 healthy controls were enrolled. To collect various information on headache attacks, headache group completed self-reported questionnaire about the characteristics of headache attacks and the migraine disability assessment (MIDAS) questionnaire. The subjective quality of sleep was evaluated in all of the subjects using the Pittsburgh sleep quality index (PSQI) and Epworth sleepiness scale (ESS). In addition, the following specific features of sleep were evaluated in 28 subjects selected randomly from each group: apnea-hypopnea index (AHI), prevalence of SDB, nocturnal oxygen saturation (SaO2), and oxygen desaturation index (ODI) as measured using a portable monitoring device. Results: The global PSQI and the prevalence of poor sleeping (global PSQI >5), ESS scores and the prevalence of daytime sleepiness (ESS score >10) were significantly higher in the headache group (both p<0.0001, respectively). The mean scores on the numerical rating scale and the MIDAS were significantly higher in the poor-sleeper group than in the good-sleeper group (p=0.0347 and p=0.0016, respectively). The global PQSI and prevalence of daytime sleepiness were significantly higher in the chronic-headache group than in the acute-headache group (p=0.0003 and p=0.0312, respectively). Conclusions: There is a significant association between headache and sleep. Especially, severity and chronicity of headache were significantly associated with sleep quality and daytime sleepiness.

• Korean Journal of Biological Psychiatry
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• v.21 no.2
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• pp.74-80
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• 2014

Objectives More than half of the elders suffer from chronic sleep disturbances. Moreover, sleep disturbances are more prevalent in patients with depressive disorder than in community dwelling elderly. In this study, we aim to estimate the risk factors of poor sleep quality and its effect on quality of life in patients with late life depression. Methods This study included 159 depressive patients aged 65 years or older who completed Pittsburgh Sleep Quality Index (PSQI). A global PSQI score of 5 or greater indicates a poor sleeper. Structural diagnostic interviews were performed using the Korean version of Mini International Neuropsychiatric Interview (MINI). Depression was evaluated by the Korean form of Geriatric Depression Scale (KGDS). Global cognition was assessed by Mini-Mental State Examination in the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease assessment packet. Quality of life was evaluated by the Korean version of Short-Form 36-Item Health Survey (SF-36). Results The frequencies of poor sleepers were 90.5% in major depressive disorder, 71.8% in minor depressive disorder, 47.1% in subsyndromal depressive disorder, and 73.0% in all types of depressive disorders. Multivariate logistic regression analysis indicated that female [odds ratio (OR) = 2.83, 95% confidence interval (CI) = 1.20-6.67] and higher KGDS score (OR = 1.13, 95% CI = 1.05-1.21) were risk factors of poor sleep quality in patients with late life depression. In the analysis of ANCOVA adjusted for age, gender, education and KGDS score, the mean scores of vitality mental health and mental component summary of SF-36 were lower in poor sleepers than in good sleepers. Conclusions Poor sleepers among patients with late life depression are very common and are associated with female and higher KGDS scores. Poor sleep quality causes a significant negative effect on mental health quality. So researchers and clinicians should be more vigilant in the evaluation and treatment of sleep disturbances in patients with late life depression.