• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.134-145
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• 1998

Facial hyperpigmentation in women, which is considered to be a serious cosmetic disability and a cause of mental distress, requires proper management. Melanocyte dendricity is a crucial factor affecting epidermal pigmentation. We found that BQ-788, the endothelin-B (ETB) receptor antagonist, blocks the formation of multi-dendricity which is induced by cocultured keratinocytes. Melanocytes in vivo show numerous dendrites which are in close contact with multiple keratinocytes, forming the epidermal-melanin unit. While melanocytes transfer their melanosomes into the neighboring keratinocytes via dendrites, keratinocytes secrete many growth factors and cytokines that influence viability, morphology, and melanin formation of melanocytes. Endothelin-1 (ET-1), prostaglandin E2(PGE2), and leukotriene-C4 (LT-C4) have been suggested as the candidates for increasing dendricity. Other reports suggested that ET-1 has stimulatory effects on proliferation and melanin formation of melanocytes in vitro. In the present study, using type-specific ET receptor antagonists, we observed how the morphology of melanocytes could be modulated in a coculture system. In addition, the roles of ET-1 for morphology and proliferation on melanocytes were evaluated in different culture media. We suggest that ET-1 increases dendricity and proliferation of melanocytes, and that its dendrite-inducing effect and mitogenic effect are regulated independently.

• Corrosion Science and Technology
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• v.2 no.3
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• pp.141-147
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• 2003

Sputter-deposited Nb-Al-Cr alloys. $3-5{\mu}m$ thick, have been prepared on quartz substrates as oxidation-and sulfidation-resistant materials at high temperatures. The oxidation or the alloys in the $Ar-O_2$ atmosphere of an oxygen partial pressure of 20 kPa follows approximately the parabolic rate law, thus being diffusion controlled. Their oxidation rates are almost the same as or even lower than those ofthc typical chromia-forming alloys. The multi-lavered oxide scales are formed on the ternary alloys. The outermost layer is composed of $Cr_2O_3$, which is"mainly responsible for the high oxidation'resistance of these alloys. In contrast to sputter-deposited Cr-Nb binary alloys reported previously, the inner layer is not porous. TEM observation as well as EDX analysis indicates that the innermost layer is a mixture of $Al_2O_3$ and niobium oxide. The dispersion of $Al_2O_3$ in niobium oxide may be attributable to the prevention of the formation of the porous oxide layer. The sulfidation rates of the present ternary alloys arc higher than those of the sputter-deposited Nb-AI binary alloys, but still several orders of magnitude lower than those of conventional high temperature alloys. Two-layered sulfide scales are formed, consisting of an outer $Al_2S_3$ layer containing chromium and an inner layer composed of $NbS_2$ and a small amount of $Cr_2S_3$. The presence of $Cr_2S_3$ in the inner protective $NbS_2$ layer may be attributed to the increase in the sulfidation rates.

• Korean Journal of Materials Research
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• v.17 no.9
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• pp.484-488
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• 2007

Mo(Ti) alloy and pure Cu thin films were subsequently deposited on $SiO_2-coated$ Si wafers, resulting in $Cu/Mo(Ti)/SiO_2$ structures. The multi-structures have been annealed in vacuum at $100-600^{\circ}C$ for 30 min to investigate the outdiffusion of Ti to Cu surface. Annealing at high temperature allowed the outdiffusion of Ti from the Mo(Ti) alloy underlayer to the Cu surface and then forming $TiO_2$ on the surface, which protected the Cu surface against $SiH_4＋NH_3$ plasma during the deposition of $Si_3N_4$ on Cu. The formation of $TiO_2$ layer on the Cu surface was a strong function of annealing temperature and Ti concentration in Mo(Ti) underlayer. Significant outdiffusion of Ti started to occur at $400^{\circ}C$ when the Ti concentration in Mo(Ti) alloy was higher than 60 at.%. This resulted in the formation of $TiO_2/Cu/Mo(Ti)\;alloy/SiO_2$ structures. We have employed the as-deposited Cu/Mo(Ti) alloy and the $500^{\circ}C-annealed$ Cu/Mo(Ti) alloy as gate electrodes to fabricate TFT devices, and then measured the electrical characteristics. The $500^{\circ}C$ annealed Cu/Mo($Ti{\geq}60at.%$) gate electrode TFT showed the excellent electrical characteristics ($mobility\;=\;0.488\;-\;0.505\;cm^2/Vs$, on/off $ratio\;=\;2{\times}10^5-1.85{\times}10^6$, subthreshold = 0.733.1.13 V/decade), indicating that the use of Ti-rich($Ti{\geq}60at.%$) alloy underlayer effectively passivated the Cu surface as a result of the formation of $TiO_2$ on the Cu grain boundaries.

• Journal of the Korean association of regional geographers
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• v.10 no.4
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• pp.800-823
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• 2004

This paper aims at examining the ways in which foreign immigrant workers in South Korea have been "forgotten" and "marginalized" in the regulatory politics of globalization and how the politics of "forgetting" has influenced the formation of immigrant local communities in South Korea. More specifically, by focusing on the immigrant community in Wongok dong, Ansan, it explores the forming questions. First, under what conditions has Wongok' dong become one of the biggest communities for foreign workers in South Korea? Second, how has the growth of the Wongok-dong immigrant community been influenced by the politics of "exclusion", and "inclusion" taking place at various geographical scales? Based on this case study, this paper suggests that the practices of "exclusion" and "forgetting" should not be seen as an inevitable outcome of globalization; instead, they need to be seen as an outcome of political processes, in which the practices of "exclusion" and "inclusion" are intertwined with one another through interactions and negotiations among different interests and ideas that take place in the multi-scalar regulatory processes, which contribute to the (material and discursive) construction of globalization.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1994.04c
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• pp.6-6
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• 1994

Har dmaterials such as cemented carbides with or without coated layer, cermets, ceramics and diamond or c-BN high pressure sintered compact are used for cutting tools, wear -resistant parts, rock drilling bits and/or high pressure vessels. These hardmaterials contain not only hard phase, but also second consituent as the element for forming ductile phase and/or sintering aid, and the mechanical properties of each material depend on (1) the amount of the second constituent as well as (2) the grain size of the hard phase. The hardness of each material mainly depends on these two factors. The fracture strength, however, largely depends on other microstructur a1 factors as well as the above two factors. For all hardmaterials, the fracture strength is consider ably affected by (3) the size of microstructur a1 defect which acts as the fracture source. In cemented carbides, the following factors which are generated mainly due to the addition of the second constituent are also important; (4) the variation of the carbon content in the normal phase region free from V-phase and graphite phase, (5) the precipitation of $Co_3$ during heating at about $800^{\circ}C$,(6) the domain size of binder phase, and (7) the formation of ${\beta}$-free layer or Co-rich layer near the surface of sintered compacts. For cemented carbides coated with thin hard substance, the important factors are as follows; (8) the kind of coated substance, (9) the formation of ${\eta}$-phase layer at the interface between coated layer and substrate, (10) the type of residual stress (tension or compression) in the coated layer which depends on the kind of coating method (CVD or PVD), and (11) the properties of the substrate, and (12) the combination, coherency and periodicity of multi-layers. In the lecture, the details of these factors and their effect on the strength will be explained.

• Bulletin of the Society of Naval Architects of Korea
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• v.7 no.1
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• pp.57-78
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• 1970

The Korea inshore fishing boats are the size up to 30G.T., and their construction commonly employs the traditional wide wooden planking. Nevertheless, the hull forms have been developed with chine-type straight-framed sections which give developable surface party, but not on the whole: especially not on the whole portion of the hull are preferable for them. Considering many merits in the boat construction, the author, excluding cases of the FRP construction by hand lay-up or spray-up method and of the ferro-cement construction, finds out no reasons to depart from the chine-type hull forms of a developable surface in future development of their hull forms, too. In this report, the author proposed new designs of the developable hull surface for four typical boats forming the main structure of Korean inshore fishing fleets; 5G.T.-class multi-purpose boat, 10G.T.-class angling and longlining boat, 20G.T.-class drift and gill netters, and 27G.T.-class stow netters, and presented the tank test results on their propulsion resistance. The tank test had two purposes; one is to present the powering schedule of the new designs and the other to investigate the resistance characteristics of this kinds of boat in comparision with those of equivalent round-type boats at operational speed ranges. Between the both types of the boat no material differences in powering are expected. Hence, the author is confident of that saving in the construction cost of the developable hull over that of the round-type boat may result in considerable contribution to the over-all boat economy.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.11
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• pp.9-16
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• 2011

We need to establish standard for the ICT based on train control system. In order to solve the ISI problem, this paper evaluate the performance of OFDM and FDE system. We seem that OFDM system is better than FDE system. In order to solve ISI problem, SC System is needed a equalizer. And another method is OFDM System. If system is used SC with a equalizer, It is better than OFDM in terms of PAPR, but this system is not easy to use Multi-Antenna technique, i.e., beam-forming and MIMO-multiplexing. And If system is used high-order modulation, BER performance is worse than OFDM. If we think about in terms of PAPR problem, considerations are considered not significant because the size of relays is not considered in the communication between trains and ground.

• Korean Journal of Materials Research
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• v.18 no.4
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• pp.199-203
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• 2008

High-efficiency phosphorescent organic light emitting diodes using TCTA-TAZ as a double host and $Ir(ppy)_3$ as a dopant were fabricated and their electro-luminescence properties were evaluated. The fabricated devices have the multi-layered organic structure of 2-TNATA/NPB/(TCTA-TAZ) : $Ir(ppy)_3$/BCP/SFC137 between an anode of ITO and a cathode of LiF/AL. In the device structure, 2-TNATA[4,4',4"-tris(2-naphthylphenyl-phenylamino)-triphenylamine] and NPB[N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] were used as a hole injection layer and a hole transport layer, respectively. BCP [2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline] was introduced as a hole blocking layer and an electron transport layer, respectively. TCTA [4,4',4"-tris(N-carbazolyl)-triphenylamine] and TAZ [3-phenyl-4-(1-naphthyl)-5-phenyl-1,2,4-triazole] were sequentially deposited, forming a double host doped with $Ir(ppy)_3$ in the [TCTA-TAZ] : $Ir(ppy)_3$ region. Among devices with different thickness combinations of TCTA ($50\;{\AA}-200\;{\AA}$) and TAZ ($100\;{\AA}-250\;{\AA}$) within the confines of the total host thickness of $300\;{\AA}$ and an $Ir(ppy)_3$-doping concentration of 7%, the best electroluminescence characteristics were obtained in a device with $100\;{\AA}$-think TCTA and $200\;{\AA}$-thick TAZ. The $Ir(ppy)_3$ concentration in the doping range of 4%-10% in devices with an emissive layer of [TCTA ($100\;{\AA}$)-TAZ ($200\;{\AA}$)] : $Ir(ppy)_3$ gave rise to little difference in the luminance and current efficiency.

• Magazine of the Korea Concrete Institute
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• v.20 no.6
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• pp.28-35
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• 2008

The Burj Dubai Project will be the tallest structure ever built by man; when completed the tower will be more than 700 meter tall and more than 160 floors. While the early integration of aerodynamic shaping and wind engineering considerations played a major role in the architectural massing and design of this multi-use/residential tower, where mitigating and taming the dynamic wind effects was one of the most important design criteria, the material selection for the structural systems of the tower was also a major consideration and required detailed evaluation of the material technologies and skilled labor available in the market at the time Concrete was selected for its strength, stiffness, damping, redundancy, moldability, free fireproofing, speed of construction, and cost effectiveness. In addition, the design challenges of using concrete for the design of the structural system components will be addressed. The focus on this paper will also be on the early planning of the concrete works of the Burj Dubai Project.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.6
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• pp.653-663
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• 2014

To cope with an increasing amount of data traffic, research efforts are being made to maximize the data rate by reducing the interference between the transmission nodes. This paper also focuses on interference control schemes utilizing antenna sub-array beam-forming. The first scheme relies on horizontal beam rotation which utilizes three types of narrow beam patterns. Different beam patterns are applied to transmit signals in rotating fashion to control the interference. The second scheme is based on user-specific sub-array beamforming, which uses the precoding matrix based on users' location and controls the amount of interference in the multi-user environment. The performance of the proposed schemes is evaluated using the computer simulation to demonstrate the performance enhancement.