• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.11
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• pp.1612-1617
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• 2003

Synchrotron X-ray micro imaging technique was employed to non-invasively monitor the water flow inside xylem vessels in a bamboo leaf. The phase contrast X-ray images clearly visualized plant anatomy and the rise of a water front inside the vessels. Consecutive X-ray images taken for 60 seconds revealed water rise kinetics against gravity in the xylem of a cut dry leaf taken from a bamboo tree. For the first time, traces of water rise, variation of contact angle between water and xylem wall as well as the internal structure of xylem were obtained. In xylem vessels, a repeating flow pattern has a typical flow velocity of 30.7$\mu\textrm{m}$/s and faster flow is established intermittently. It is concluded that the transmission type of X-ray micro imaging can be used as a powerful tool to investigate the ascent of sap in the xylem vessels at a resolution higher than that of MRI.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.1
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• pp.42-54
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• 2009

Contrast to the 6-DOF nonlinear dynamic modeling of nonlinear tracking problem, 3-DOF point-mass modeling of flight mechanics is efficient and adequate for applying the trajectory optimization problem. There exist limitations to apply an optimal trajectory from point-mass modeling as a reference trajectory directly to conduct the nonlinear tracking control, In this paper, new matching trajectory optimization scheme is proposed to compensate those differences of mismatching. To verify performance of proposed method, full ascent three-dimensional flight trajectories are obtained by reflecting the real constraints of flight conditions and airship performance with and without jet stream condition. Then, they are compared with the optimal trajectories obtained from conventional method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.185-188
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• 2008

This paper introduces the Bootstrap method for statistical analysis of noise and vibration spectrum in aeronautic and space fields. Generally, all components of a launch vehicle and its payloads are subjected to high intensive noise and vibration environment during the lift-off phase and the ascent phase through Mach =1 and Max Q. In order to verify their survivabilities against these severe vibroacoustic environments during qualification tests and acceptance tests, it is most important to estimate the proper upper limits of the environmental condition. Although NASA has typically utilized the Normal Tolerance Limit method in deriving these levels, the reference[1] says that the Bootstrap can be also an alternative method to estimate the maximum expected environments. In this paper, a general procedure of the Bootstrap method is summarized, and it is applied to analyze acceleration power spectral density functions, which were measured during acoustic test on the upper stage of KSLV-I.

• Korean Journal of Oriental Medicine
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• v.10 no.1
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• pp.63-80
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• 2004

The Sasang constitution food is classified by Sadang theory(四黨論), Aroma-Scent-Fluid-Taste(馨臭液味), Inhale-Exhale-Incomings-Outgoings(呼吸出納), Ascent-Descent-Open-Close(升降開闔), Healthy Energy(保命之主), which is different from the Oriental medicine herb classification of traditional oriental medicine. So, we obtained the result of the characteristic of radish, one of much used food materials by examining ancient documents as follows. First, today 'Rae(來)' is used as to come' but in ancient days, was used as 'wheat'. Radish(萊服) is the word made by meaning which removes and overcomes the poison of wheat Second, Ancient people realized the power of its Inhale Disperse Qi (呼散之氣) when the root of radish raises quickly from the soil, and recognized that radish has such a good dissolving function when seeing Bean-curd becomes soft if radish is added to Bean-curd dish. That’s why they classified that radish is lung medicine, and used it as Taeumin type medicine. So if someone is suffocated by the smoke and has indigestion, chronic asthmatic coughing, now we use radish by applying the Inhale Disperse Qi of radish.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.725-732
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• 2013

This paper presents a torque distribution algorithm for improving the stability and mobility of a wall-climbing robot platform. During ascent, the pitch moment caused by the payload or external disturbances separates the robot's triangular tracks from the wall, significantly deteriorating its stability. Moreover, the reaction forces stemming from the increase in the pulling force may degrade the robot's mobility. Thus, it is very important to minimize the reaction forces acting on the triangular tracks, as well as the fluctuations in the pulling force, during the climb. Through dynamic modeling of the proposed robot platform, we demonstrated the dependence of the robot's stability and mobility on the torque distribution of the triangular tracks. Extensive simulations using different climbing speeds were used to significantly improve the stability and mobility of the proposed robot platform.

• The Journal of Asian Finance, Economics and Business
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• v.3 no.3
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• pp.39-55
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• 2016

The rapid expansion of China's trade surplus since the mid-eighties and picking up until the onset of 2008-09 global financial crisis has been a key development in the world economy. While growing trade surplus of China has been viewed with cynicism borne out of an undervalued Yuan and for having being a member of WTO since 2001, many others argue that China's trade surplus reflect changes in China's economic and trade structure and associated shifts in its role within regional and global production chains. We address this issue by analyzing: (i) China's growing and changing trade structure as well as changing structure of trade surplus with the rest of the world, USA, Europe, Japan and rest of Asia, (ii) China's revealed comparative advantage (RCA) with the rest of the world, and (iii) how China's trade policies resulted into a shift in China's trade structure. We find that, not only China has made significant inroads in the world trade since its admission to WTO, but also there has been a noticeable shift in China's trade structure with specialization in high-end technology industries wherein China's exports aided by a well calibrated FDI policy.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.4
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• pp.39-50
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• 1998

The object of this study was to examine and analyze the environmental deterioration of three major trails and around peak area of Moaksan Provincial park in 1996. Trails are mostly made up at ridgeline and the slope of them is gentle. Mean trail width is 3.6m, and total length of branch trails is 982m in survey area. The environmental deterioration is derived from trail extension. Maximum eroded depth and cross-section area loss are 89cm and 14,050cm2 respectively, and gully erosion type appears at many sites. The environmental deterioration of trails is very heavy at the sections from Khui to Moaksan peak and from Moakchong to ascent part around the peak. The entire width, branch trail, maximum depth, cross-sectional area loss and surface roughness, as the indexes of trail conditions, are significantly greater at the more heavily used trails. Amount of erosion is influenced by eroded depth, longitudinal slope, runoff influence and entire width in descending order as well as the amount of use. Safety and protection facilities on the trail such as stone and soil stairs, rope handrail, stone channel and soil ditch work are built, but they are very deficient. Bared lands about 4,900m2 and fill slopes are caused and formed by recreation activities and constructions around peak area. It is required to carry the recess system and to conserve and rehabilitate the destroyed trail sites and bare fill slopes as soon as possible, before the environmental deterioration becomes critical because of increased used amount in consequence of construction of recreation parks.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.4
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• pp.445-453
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• 2016

Objectives: The objective of this study is to assess relative safety level of the decompression tables in Ministry of Employment and Labor Public Notice No. 2014-28 in comparison with overseas decompression tables. Methods: Decompression tables in the Public Notice No. 2014-28 were compared with examples from Japan, the USA, Canada, and France in terms of ascent rate, surface intervals after exceptional exposures, oxygen decompression and allowable partial pressure, depth limits in air diving, no-decompression limits, and decompression time and methods. Results: Public Notice No. 2014-28 does not include air diving depth limits, exceptional exposure limits, mandatory surface intervals after exceptional exposures, oxygen decompression, and surface decompression schedules. Its decompression time was found to be the shortest among the five decompression tables. Conclusions: Public Notice No. 2014-28 has the lowest safety level in comparison with overseas decompression tables. Deck decompression chambers are not applicable due to no regulations on surface interval and oxygen use in the chamber for decompression.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.574-582
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• 1999

This paper discusses the multi-level optimization method in dynamic optimization problems through stiffened plate of ship structures. In structural optimization the computational cost increases rapidly as the number of design variables increases. And we need a great amount of cal-culation and time on problems of modified dynamic characteristics of large and complicated struc-tures. In this paper the multi-level optimization is proposed which decreases computational time and cost. the dynamic optimum designs of stiffened plate that control the natural frequency and minimize weight subjected to constraints condition are derived. The way to apply the multi-level optimization methods in this study follow: In the first step the dynamic characteristics is controlled for the two-dimensional model of stiffened plate by sensitivity analysis and quasi-least squares methods. In the second step the cross-section of the stiffener is decided so that the weight is minimized under needed constraints by the steepest descent or ascent method. In the third the three-dimensional model is made based on the results of the first step and the second step confirmation and finer tuning of the objective function are carried out. It is shown that the results are effective in the optimum modification for dynamic characteristics of the stiffened plate.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.321-326
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• 2015

Plackett-Burman (PB) and Box-Behnken (BB) experimental designs were used to optimize fermentation variables for the biotransformation of glycyrrhizin (GL) to monoglucuronyl-glycyrrhetinic acid (MGGA). The PB design was first used to screen the important factors among the medium variables. The steepest ascent method was used to approach the optimum range for each of these factors. The BB design was finally used to analyze the response surfaces of the screened factors for further optimization. The optimized conditions for this system were 0.7 g/L $MgSO_4{\cdot}7H_2O$, 1.19 g/L GL, and cultivation for six days. The biotransformation of GL to MGGA could reach up to 35.72%, which is a good result for this kind of transformation.