• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.185-187
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• 2013

일반적으로 사람은 육체적, 정신적 그리고 심리적 자극에 반응할 경우 스트레스(Stress)가 유발된다. 이 스트레스는 정상적인 업무수행 뿐만 아니라 건강에 악영향을 미칠 수 있고, 피로누적의 한 원인이 되기 한다. 특히 열악한 환경에서 직무를 수행하는 선원에게 있어서 스트레스는 해양사고의 직간접적인 요인이 될 수 있기 때문에 선박 인적자원관리의 한 측면으로 중요하게 다루어질 필요가 있다. 이 연구는 해운기업이 선원의 인사 및 안전관리 시스템에 활용할 수 있는 선원용 스트레스 평가도구를 개발하기 위한 것으로, 기본영역, 가족생활영역, 재정영역, 직업 및 선박생활영역에 대하여 90개의 항목으로 구성된 설문도구를 개발하여 설문조사를 수행하였고, Holmes & Rahe의 사회적응평가도구의 항목 및 평가지수와 비교분석하여 한국 선원의 문화적 차이를 고려한 설문도구를 개발하기 위한 기초적 연구를 수행하였다.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.4
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• pp.83-89
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• 2002

Oil ring and sound proof rubbers are very much important because the cause of oil leakage are mostly occupied by these rubbers. So good oil rings are the necessary parts of autolife expansion. The expensive selection system keeps from factory automation and most works are established manually. These study has been the basis of test equipments automatically in rubber products and DCT algorithm has been applied and the selection system is made efficiently differentiating good or poor.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.177-182
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• 2014

Purpose : The goal of this study was to compare and analysis the dose distribution and treatment time between Tomotherapy planning with fixed jaw(FJ) and dynamic jaw(DJ). Materials and Methods : Seven patients were selected in the study including five common clinical cases(brain, head and neck(HN), lung, prostate, spine). 1) Helical Tomotherapy plans with FJ and DJ were generated with the same planning parameters such as Modulation factor, Pitch and Field width. 2) Tomo_edge plans with a larger field width were generated to compare to conventional HT delivery with fixed jaw. Dosimetric evaluation indices for target coverage are Dmin, Conformity index(CI) and for whole body including target are $V_{10%}$, $V_{25%}$, $V_{50%}$, $V_{75%}$ using Dose-volume histogram(DVH). Also, Treatment time and Cumulative MU were used for clinical review on Tomo_edge. Results : In case of using the same field width of Tomotherapy planning with FJ and DJ, the averaged variations were $V_{10%}$: -11.91%, $V_{25%}$: -7.6%, $V_{50%}$ :-4.75%, $V_{75%}$: -1.04%. Tomo_edge with a larger field width provides the averaged variations for target coverage: Dmin: -0.72%, CI: -1.25% and also shows the tendency of a sharp $V_{x%}$ decline in low dose area. The clinical improvements in the larger field width with DJ were observed in the treatment time, ranging from -51.21% to -15.11, and the Cumulative MU decrease, ranging from -57.74% to -15.31%. Conclusion : Target coverage achieved by FJ and DJ with the same field width has little differences. But integral doses on whole body efficiently decreased. Compared to the conventional HT delivery, Tomo_edge with a larger field width presents a little worse target coverage. However, it provides faster treatment delivery and improved cranial-caudal target dose conformity. Therefore, Tomo_edge mode is efficient in improving the treatment time and integral dose while maintaining comparable plan quality in clinic.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.4
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• pp.537-548
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• 2022

It is important to design the pavement thickness considering heavy-duty traffic loads, which can cause excessive stress and strain in the pavement. Port-rear roads and industrial roads have many problems due to early stress in pavement because these have a higher ratio of heavy loads than general roads such as national roads and expressways. Internationally, composite pavement has been widely applied in pavement designs in heavy-duty areas. Composite pavement is established as an economic pavement type that can increase the design life by nearly double compared to that of existing pavement while also decreasing maintenance and user costs. This study suggests a thickness design method for composite pavement using roller-compacted concrete as a base material to ensure long-term serviceability in heavy-duty areas such as port-rear roads and industrial roads. A three-dimensional finite element analysis was conducted to investigate the mechanical behavior and the long-term pavement performance ultimately to suggest a thickness design method that considers changes in the material properties of the roller-compacted concrete (RCC) base layer. In addition, this study presents a user-friendly catalog design method for RCC-base composite pavement considering the concept of linear damage accumulation for each container trailer depending on the season.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6C
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• pp.637-644
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• 2006

This paper presents performance and implementation comparisons of standard and fast DCT algorithms that are commonly used for subband filter bank in MPEG audio coders. The comparison is made according to the architectural difference of the implementation hardware. Fast DCT algorithms are known to have much less computational complexity than the standard method that involves computing a vector dot product of cosine coefficient. But, due to structural irregularity, fast DCT algorithms require extra cycles to generate the addresses for operands and to realign interim data. When algorithms are implemented using DSP processors that provide special operations such as single-cycle MAC (multiply-accumulate), zero-overhead nested loop, the standard algorithm is more advantageous than the fast algorithms. Also, in case of the finite-precision processing, the error performance of the standard method is far superior to that of the fast algorithms. In this paper, truncation errors and algorithmic suitability are analyzed and implementation results are provided to support the analysis.

• Journal of the Korean GEO-environmental Society
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• v.11 no.12
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• pp.5-11
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• 2010

If the groundwater in rock joint is changed into ice, it induces the stress increment by volume increase. Also, if the ice is changed into groundwater again, the stress in joint decreases by volume decrease. The accumulated displacement and fatigues of joints are increased by the stress-hysterisis, induced from the continuous frost-thawing. Also the shear strength is decreased by them continuously. The stress-hysterisis is affected by the atmospheric temperature changes, whose behavior is visco-elasticity, usually. Therefore, Kelvin model could be used to analyze the frost-thawing behavior in winter. The measured data of total 5 points are examined, which are composed of 3 points of shallow joints and 2 points of deep joints. Because shallow weathered rocks have many joints, a lot of Kelvin model are connected and the behaviors are complicated. In case of deep joints, simple Kelvin model is applied and the behaviors are also simple.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.5
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• pp.399-405
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• 2010

The accumulated displacements and fatigues of rock are increased by the stress-hysteresis, induced from repeated frost-thawing. Also the shear strength is decreased by them continuously. The stress-hysteresis is affected by the atmospheric temperature changes, whose behavior is visco-elasticity, usually. Therefore, to do ideal body analysis, Kelvin model could be used to analyze the frost-thawing behavior in winter. In general, rock slope failure occurs by the deterioration of rocks, which is caused by the repetition of freezing-thawing process. In order to keep the safety of such rock mass structures the deterioration process of rock needs to be described quantitatively using some meaningful parameters. In this work, the deterioration process in freezing-thawing cycle of tuff, which is a famous soft porous rock, is investigated through laboratory tests and successfully described as a differential equation for the change of porosity. And then, the deterioration of the mechanical properties of rock, such as Young's modulus and uniaxial compressive strength, are quantitatively described as a function of the porosity.

• Journal of Digital Convergence
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• v.15 no.8
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• pp.501-509
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• 2017

The purpose of this study was to review the effects of the physical fatigue induced by overtraining on cognitive information processing and emotional change of athletes by neurophysiologic study. And to provide basic data for the athletes and coaches in the sports field to improve understanding of the overtraining symptoms from the brain physiological point of view. We reviewed the domestic and international academic materials and research reports published in the last 20 years using electronic databases and examined the literature that is consistent with the purpose of this study among the retrieved documents. Based on the reviewed literature, we examined the cognitive information processing and emotional change of the athlete according to the training, and overtraining can accumulate the fatigue of the body, which can cause severe side effects in terms of cognitive ability and emotional ability of athletes as well as deterioration of performance. The study using P300 and EEG cerebral hemispheric asymmetry difference indices also confirmed the possibility of a new approach to understand psychological and physiological effects of overtraining on information processing and emotional changes.

• Progress in Medical Physics
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• v.25 no.4
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• pp.193-198
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• 2014

The purpose of this study is to see the feasibility of the newly developed 2D dosimetry system using phosphor screen for helical tomotherapy. The cylindrical water phantom was fabricated with phosphor screen to emit the visible light during irradiation. There are three types of virtual target, one is one spot target, another is C-shaped target, and the other is multiple targets. Each target was planned to be treated at 10 Gy by treatment planning system (TPS) of tomotherapy. The cylindrical phantom was placed on the tomotherapy table and irradiated as calculations of the TPS. Every frame which acquired by CCD camera was integrated and the doses were calculated in pixel by pixel. The dose distributions from the fluorescent images were compared with the calculated dose distribution from the TPS. The discrepancies were evaluated as gamma index for each treatment. The curve for dose rate versus pixel value was not saturated until 900 MU/min. The 2D dosimetry using the phosphor screen and the CCD camera is respected to be useful to verify the dose distribution of the tomotherapy if the linearity correction of the phosphor screen improved.

• Journal of Korean Society of Forest Science
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• v.98 no.4
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• pp.458-463
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• 2009

The purpose of this study was to evaluate the changes of surface runoff by comparisons between burned and unburned area after forest fire. The amount of surface runoff in burned area was more high 1.72 times in the year of fire, 1.44 times in one year later, 1.38 times in five years later and 1.16 times in ten years later than those of unburned area. Therefore, surface runoff in the burned area almost tended to be stabilized like unburned area ten year later after forest fire. The most affecting factors on the amount of surface runoff in burned and unburned area were number of unit rainfall, number of rainfall accumulated and unit rainfall. But coverage was shown to mitigate the amount of surface runoff in burned and unburned area.