• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.1
• /
• pp.32.3-33
• /
• 2017

Utilizing both the existing observational data for Orion A and the TRAO $^{13}CO$, $^{12}CO$ data for $1^{\circ}{\times}1^{\circ}$ region centered on M42 collected in 2012, we found a clear piece of evidence for a collision of a cloud with the OMC-1. This cloud has a shape like a long cylinder of ${\sim}0.1pc{\times}2pc$ in size, and has a well developed train of clumps of about a few solar masses, and is situated in the dark dust complex between M42 and M43. The cloud's motion is analysed to be moving at about $2.6km\;s^{-1}$, and is calculated to transverse the Orion Nebula ~2 pc above from the nebula center, toward the direction of about $60^{\circ}$ to the line of sight. This cloud had undergone a tidal splitting about a million years ago and had formed a very thin and long cylindrical core well before being engaged in the collision. General implications of this phenomenon are discussed in relation to star formation mechanisms in the GMC.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.35 no.2
• /
• pp.18-25
• /
• 2003

The adsorption of co-cationic dual polymer system was investigated as was the fiber dispersion stability of a paper stock suspension. Polyaluminum chloride(PAC) and polyamidoamine epichlorohy-drin(PAE) polymers were used as wet-end additives. The adsorbed amounts of PAE polymer in a wet stock were measured by using polyelectrolytic PCD titration. The sheet forming experiments were carried out in a standard handsheet machine. Fiber dispersion stability and relative retention were evaluated in terms of M/K non-uniformity index and sheet basis weight, respectively. The PAE polymer adsorption of Langmuir-isothermal type decreased with increasing PAC addition level. The combination of the two cationic polymers presumably exerts a site-blocking effect by the low molecular weight PAC which gives a partial charge neutralization at a minimum level of addition. From a thermodynamic view point of PAE adsorption, an increase in adsorption entropy and a decrease in train number suggests that the PAR polymer has an extended conformation structure that potentially leads to an enhancement of the fiber dispersion stability. This conclusion is supported by handsheet experiments that examined the PAC-PAE dual polymer effects on the sheet formation and retention.

• International Journal of Railway
• /
• v.4 no.4
• /
• pp.109-115
• /
• 2011

An analysis and design method for reducing aerodynamic noise in high-speed trains based on biomimetics of noiseless flight of owl is proposed. Five factors related to the morphology of the flight feather have been selected, and the candidate optimal shape of the flight feather is determined. The turbulent flow field analysis demonstrates that the optimal shape leads to diminished vortex formation by causing separation of the flow as well as allowing the fluid to climb up along the surface of the flight feather. To determine the effect of scaling of the owl's flight feather on the noise reduction, a two-fold and a four-fold scaled up model of the feather are constructed, and the numerical simulations are carried out to obtain the aerodynamic noise levels for each scale. Original model is found to reduce the noise level by 10 dBA, while two-fold increase in length dimensions reduces the noise by 12 dBA. Validation of numerical solution using wind tunnel experimental measurements is presented as well.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.601-602
• /
• 2005

In the cold and temperate regions of Korea the icing and ice coats on 25 kV overhead contact wire during winter is a very serious problem. This generates shocks at the mechanical interface of the collecting strips of the pantograph and the contact wire and extra electrical resistance, which may affect quality of current collection at the contact wire / collecting strips of pantograph interface. De-icing operations should be performed just before train operation to avoid the formation of another ice layer. This paper presents temperature analysis of the de-icing system which could be applied to the overhead contact wire of railways.

• Korean Journal of Metals and Materials
• /
• v.46 no.5
• /
• pp.304-309
• /
• 2008

Magnesium alloys containing $Mg_2Si$ particles, as a promising cheap heat-resistant magnesium alloy for automobile power train parts applications, are attracting more attention of both material scientists and design engineers. Modification of the Chinese script shape $Mg_2Si$ particle is a key for using this alloy in sand or permanent mould casting. In the present work, the modification effect of Sr and Sb on the corrosion properties of the Mg-5Al-2Si alloy was investigated. Sr or Sb addition promoted the formation of fine polygonal shape $Mg_2Si$ particles by providing the nucleation sites. Sr was more effective element than Sb for shape modification of Chinese script shape $Mg_2Si$. Such improved microstructure of the modified alloy resulted in large improvement in corrosion resistance as compared to unmodified Mg-5Al-2Si alloy.

• Journal of Navigation and Port Research
• /
• v.32 no.1
• /
• pp.47-56
• /
• 2008

With rapid growing of the Northeastern Asia, the interest for the connection of Infrastructure that was behind of interesting until now is getting larger. In a line of same connection, UN-ESCAP are forwarding transcontinental railway project, asian highway project et al.. And this study aimed at analysis on the effect that extended to a space by Korea-Japan undersea tunnel project. In aspect of a national land balanced-development to solve various problems such as overcrowding in capital region, unbalanced state by regions, weak exchange between South and North Korea, and weakness of national land basis to prepare for unification et al., this study consulted the economic potentiality model as a analysis method to examine an effect. In this analysis, I used 24 scenarios including all cases by combination of 3 scenarios for Korea-Japan undersea tunnel, 4 scenarios for transportation modes in the section of undersea tunnel, and 2 scenarios for adjacency infrastructure. Transportation modes in the section of undersea tunnel are railway, car-train, mixing way of railway and car-train, and mixing way of road and railway. Adjacency infrastructure applied railway and road. In all scenarios, Korea showed higher growth potentiality than Japan. Also, proposal plan C route relatively showed better in national land balanced-development than other proposal plans. The growth potentiality relatively appeared higher by buildup of a connection together with non-capital regions from the construction of Korea-Japan undersea tunnel. In aspect of Northeastern Asia, it resulted in a increasing of trade and chance of network formation in the region of Asia through infrastructure connection. But, in considering passenger and various factors that extended to the economic growth, this analysis have some limitation. Therefore, I hope that deep studies will continuously perform with various factors.

• Korean Security Journal
• /
• no.18
• /
• pp.143-167
• /
• 2009

As of entering the 21st century, a trend in the field of a private security industry among the advanced countries have been increased a qualification system and train session to meet the needs of professionalism. Intensifying the professionalism in Korea, education and train system has been initiated to change but the oligopoly market already formulated due to impractical selection standard and management of education system. Issuing certification and offering basic training through a designated institution for the purpose of improving quality of the private security industry worker, its practical effectiveness were lower than expectation. Rather certification-holder or security agency, institution or truster's rent-seeking behavior have been increased by occupational licensing system. The founded results, which were associated to problems in selecting and educating to the private security guard, in this study were that any verification has been initiated towards dual-system in official approval and structural problems in education system, and non-existence of verification for professionalism and management capability to security agency owner and its upper managerial level. Current a dual system in an officially authorized verification system and completion of security guard credential requested change to an unified official qualification verification system to solve those problems. Ranges of an applicant to the unified official qualification verification system should be extend to the whole population in the private security industry. Moreover, minimization of the dead-weigh loss, which is caused by oligopoly phenomenon while using its market-dominant status, increasement number of designated institution, which allows self-regulating competition, and endowment of autonomy, which is in selecting education and agency, were requested to solve the problems in selecting and educating to the private security guard. In order to minimize stated problems while maintaining objectiveness, a new manage and supervise institution, which is called a 'private security industry committee', should be establish. The private security industry committee is a formation of governance network which are participated from professional group to civil organization.

• Journal of the Korean Society for Railway
• /
• v.15 no.6
• /
• pp.623-630
• /
• 2012

Formation used as trackbed foundation for providing vertical bearing capacity onto rail foundation are composed of crushed stones usually with certain type of grain size distribution. Permanent deformation in trackbed foundation can be generated by increasing number of load repetition due to train traffic increases, causing track irregularity. In this study, a specially prepared trackbed foundation materials (M-40) used in Korea has been tested using a large repetitive triaxial compression apparatus in order to understand resilient and permanent deformation characteristics of the material. From these test results, resilient and permanent deformation characteristic are analyzed so that a permanent deformation model is developed which can consider number of load repetition N, confining stress (${\sigma}_3$), shear stress ratio(${\tau}/{\tau}_f$) and stiffness of the material.

• Korean Institute of Interior Design Journal
• /
• v.19 no.6
• /
• pp.59-66
• /
• 2010

The purpose of this study is to examine how the perception of lives and studies in the Joseon Dynasty period, and the concept of its sculptures can be reflected in Korean traditional pavilion place, from the perspective of Nomadism as a western philosophy of this era. Nomadism literally refers to way of life of peoples who do not live continually in the same place but move cyclically searching for temporary centres whose stability depends on the availability of food and water supply or pastures for their livestock. In recent years, the term encompasses three general types: job nomads, digital nomads and ubi-nomads, which represent distinct features of modern society. Its concept implies looking for the new creative possibility through the liberation of desire and the breakaway to another thinking through continuous formation and transformation. Likewise, Korean traditional pavilion is the architecture to take a quick rest while walking in the mountains. This open place thus connects surroundings with people who are allowed to assimilate with nature as well as train their mind by following the law of nature, in order to finally reach the celestial state of mind. Knowing how to see, enjoy and appreciate the arts very close to nature, our ancestors were able to learn aesthetic activities. After recognizing Korean traditional pavilion as the potential place of unification of heaven and men which is Korean scholor's lifestyle and outlook on the world, this study accordingly will identify the value and meaning of Korean traditional architecture according to Nomadism in the occidental point of view.

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