• The KIPS Transactions:PartC
• /
• v.14C no.1 s.111
• /
• pp.95-104
• /
• 2007

Mobile multimedia services such as TV-call or video streaming are gradually becoming popular in the 3rd or more generation mobile network (IMT-2000). Multimedia traffic is expected to continue increasing into the coming years, and IP technology is considered to be the efficient way of transporting such huge volumes of multimedia traffic. IP-based IMT network platform represents an evolution from IMT-2000. The structure of IP-based IMT network as ubiquitous platform is three-layered model : Middleware including Network Control PlatForm (NCPF) and Service Support PlatForm (SSPF), IP-BackBone (IP-BB), access network including sensor network. Mobility Management (MM) architecture in NCPF is proposed for IP-based IMT network in order to manage routing information and location information separately. The generous existing method of multicast control in IP-based IMT network is Remote Subscription. But Remote Subscription has problem that should be reconstructed whole multicast tree when sender in multicast tree moves to another area. To solve this problem, we propose the way to put Multicast-manager in NCPF.

• Journal of the Korean Electrochemical Society
• /
• v.6 no.1
• /
• pp.1-5
• /
• 2003

[ $LiNi_{1-x}Co_xO_2\;(x=0.0\~1.0)$ ] powders were synthesized by citrate method, and their crystal structures and electrochemical performance as the cathode material in Li secondary batteries were analyzed. X-ray diffraction analysis revealed that all the samples carry a single phase regardless of the Co substitution. The results of Rietveld refinement suggested that the crystal structure of solid solutions varies according to the Co substitution. When the Co substitution is low $(x=0.3\~0.5)$, the solid solutions carry a cubic-like structure with a relatively small value in the ratio of lattice parameters (c/a). The solid solutions made with a higher Co substitution (x=0.7), however, exhibit a layered structure with a higher c/a ratio. This difference was also observed in the electrochemical voltage spectroscopy (EVS) profiles, whereby the Co component in scarcely substituted materials shows a charging reaction at $3.7V\;(vs.\;Li/Li^+)$, but in the heavily substituted ones at 3.92V.

• Journal of the Korean Vacuum Society
• /
• v.7 no.1
• /
• pp.59-65
• /
• 1998

Multi-layer diamond-like carbon (DLC) films were deposited by 13.56 MHz r.f. PACVD method. Multi-layer DLC film was composed of 2.5 $mu extrm{m}$ thick pure DLC filml and 0.2$\mu\textrm{m}$ thick Si incorporated DLC (Si-DLC) film as a surface layer. Tribological behaviors of the multi-layer DLC film were investigated with a ball-on-disk type tribometer in ambient atmosphere using AISI 52100 steel ball. Low friction coefficient (<0.1) period increased with increasing the Si content in the surface Si-DLC film. The wear rate after 44,000 cycles and 158,400 cycles were the $2.5\times10^{-8}\sim1.8\times10^{-7}\textrm{mm}^3$/rev. and $7.1\times10^{-9}\sim1.8\times10^{-8}\textrm{mm}^3$/rev.,respectively. The wear rate of the multi-layer DLC film after 158,400 cycles was about 2 times smaller than that of pure DLC films of 2.7 $\mu\textrm{m}$ thickness. This high wear resistance and low friction coefficient was caused by the formation of Si oxide layer on the wear scar surface, as confirmed by the debris composition analysis. It was further shown that this si oxide debris layer on the wear scar surface is formed again even after removing the debris of the steel ball, which maintain the low friction coefficient between multi-layer DLC films and steel ball.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.15 no.2
• /
• pp.77-84
• /
• 2012

This study suggested the planting model of Zelkova serrata communities in the areas with the warmth index of both 80~100 and $100{\sim}120^{\circ}C{\cdot}month$. Warmth index was calculated with 449 weather points using inverse distance weighted interpolation method. The planting species were selected by correlation analysis between Z. serrata and each species of four or more frequency among the 36 relev$\acute{e}$ surveyed for this study. The result of this study is summarized as follows : Warmth index of Z. serrata communities was among $74{\sim}118^{\circ}C{\cdot}month$. Results of the correlation analysis between Z. serrata and each species observed that the Z. serrata belongs to the tree layer with warmth index of 80~100 and $100{\sim}120^{\circ}C{\cdot}month$. On the other hand, the species of Carpinus laxiflora, Quercus serrata, Prunus sargentii and Platycarya strobilacea appeared only in the tree layer with warmth index of $80{\sim}100^{\circ}C{\cdot}month$. Z. serrata and Styrax japonica appeared in the subtree layer with the warmth index of 80~100 and $100{\sim}120^{\circ}C{\cdot}month$, while Acer pseudosieboldianum, Lindera erythrocarpa, Acer mono, Quercus serrata, etc. appeared in the subtree layer with the warmth index of $80{\sim}100^{\circ}C{\cdot}month$. Z. serrata, Ligustrum obtusifolium, Lindera obtusiloba, Callicarpa japonica and Zanthoxylum schinifolium all appeared in the shrub layer with the warmth index of 80~100 and $100{\sim}120^{\circ}C{\cdot}month$. Lindera erythrocarpa, Orixa japonica, Staphylea bumalda, Akebia quinata and Sorbus alnifolia appeared in the shrub layer with the warmth index of $80{\sim}100^{\circ}C{\cdot}month$ and Styrax japonica and Stephanandra incisa appeared in the shrub layer with the warmth index of $100{\sim}120^{\circ}C{\cdot}month$, The numbers of each species planted in a $100m^2$ area of the Z. serrata community were suggested as follows : five in tree layer, five in subtree layer and nine in shrub layer. The average area of canopy are suggested to be about $86m^2$ for tree layer, $34m^2$ for subtree layer and $34m^2$ for shrub layer.

• Journal of the Korean GEO-environmental Society
• /
• v.6 no.3
• /
• pp.47-54
• /
• 2005

In many practical cases, design methods of pile have been used mainly semi empirical bearing capacity equations. It can be done that confirmation of pile bearing capacities through using of dynamic and static tests during constructing or after constructions. If a prediction of layered point pile bearing capacity could be done through simple tests during field investigation, it could be done that more reliable design of pile than a prediction of using semi empirical equations or static formulations. This paper suggests a method to estimated point bearing capacity during in-situ investigation by using the dynamic rod model pile and verifies the point bearing capacity compare with results of static pile load tests. From test results, the unit ultimate point bearing capacities are relatively similar through a dynamic rod model pile tests and static pile load tests. The unit ultimate point bearing capacity by using N value is shown about 50 % value of measured unit ultimate point bearing capacity from field test result and the prediction of the unit ultimate point bearing capacity by using N value is shown very conservative, illogical and uneconomical pile designs.

• Journal of the Korean Magnetics Society
• /
• v.17 no.1
• /
• pp.10-13
• /
• 2007

Single crystalline, $LuFe_2O_4$, was grown by the floating zone method. The crystal structure was a two-dimensional layered-type rhombohedral($R\={3}mh$) structure, with an $a_0=3.440(2)\;{\AA}\;and\;a\;c_0=25.263(2)\;{\AA}$. The magnetic $N\'{e}el$ temperature($T_N$) was determined to be 250 K. The $M\"{o}ssbauer$ spectrum at 12 K was fitted with four sextet sets which was resulted from the crystal structure. The spectrm at room temperature consisted of three singlets and a doublet with the electric quadrupole splitting. The isomer shift($\delta$) value of the singlet was $0.20{\pm}0.01mm/s$ relative to the Fe metal indicating the $Fe^{3+}$ valence state, and the value of the doublet was $0.70{\pm}0.01mm/s$ indicating $Fe^{2+}$. The $M\"{o}ssbauer$ absorption area ratio between $Fe^{3+}$ and $Fe^{2+}$ at room temperature was 1:1. The doublet phase of spectra gradually disappears by up to 360 K. At 360 K, the spectrum shows the singlet phase. We suggested that the spontaneous polarization effect of $LuFe_2O_4$ was caused by the change of iron behavior.

• Macromolecular Research
• /
• v.11 no.4
• /
• pp.207-223
• /
• 2003

For last five years, we are developing the novel local drug delivery devices using biodegradable polymers, especially polylactide (PLA) and poly(D,L-lactide-co-glycolide) (PLGA) due to its relatively good biocompatibility, easily controlled biodegradability, good processability and only FDA approved synthetic degradable polymers. The relationship between various kinds of drug [water soluble small molecule drugs: gentamicin sulfate (GS), fentanyl citrate (FC), BCNU, azidothymidine (AZT), pamidronate (ADP), $1,25(OH)_2$ vitamin $D_3$, water insoluble small molecule drugs: fentanyl, ipriflavone (IP) and nifedipine, and water soluble large peptide molecule drug: nerve growth factor (NGF), and Japanese encephalitis virus (JEV)], different types of geometrical devices [microspheres (MSs), microcapsule, nanoparticle, wafers, pellet, beads, multiple-layered beads, implants, fiber, scaffolds, and films], and pharmacological activity are proposed and discussed for the application of pharmaceutics and tissue engineering. Also, local drug delivery devices proposed in this work are introduced in view of preparation method, drug release behavior, biocompatibility, pharmacological effect, and animal studies. In conclusion, we can control the drug release profiles varying with the preparation, formulation and geometrical parameters. Moreover, any types of drug were successfully applicable to achieve linear sustained release from short period ($1{\sim}3$ days) to long period (over 2 months). It is very important to design a suitable formulation for the wanting period of bioactive molecules loaded in biodegradable polymers for the local delivery of drug. The drug release is affected by many factors such as hydrophilicity of drug, electric charge of drug, drug loading amount, polymer molecular weight, the monomer composition, the size of implants, the applied fabrication techniques, and so on. It is well known that the commercialization of new drug needs a lot of cost of money (average: over 10 million US dollar per one drug) and time (average: above 9 years) whereas the development of DDS and high effective generic drug might be need relatively low investment with a short time period. Also, one core technology of DDS can be applicable to many drugs for the market needs. From these reasons, the DDS research on potent generic drugs might be suitable for less risk and high return.

• Journal of the Korean Electrochemical Society
• /
• v.9 no.2
• /
• pp.64-69
• /
• 2006

Cathode materials of Al-doped $Li(Ni_{1/3}Co_{1/3}Mn_{1/3-x}Al_x)O_2$ (x=0.0, 0.005, 0.01 0.05) for lithium ion batteries were synthesized with ultra-sonic spray pyrolysis method and single-step heat treatment. No secondary phases were found in all synthesized powders. The intensity ratio of $I_{003}\;to\;I_{104}$, however, slightly decreased and the particle size increased with the Al contents. The cells with bare, 0.5 and 1.0 at% Al-doped powders showed the initial discharge capacities of 182, 180 and $184mAhg^{-1}$ in a voltage range of $3.0\sim4.5V$ at 1C rate, and the capacity retentions of 81, 77 and 78% at the end of 30 cycles, respectively. But in the voltage range of $3.0\sim4.6V$, the Al-doping significantly enhanced the cycle stability. For example, the discharge capacity after 50 cycles was maintained to 70% in the 0.5 at% Al-doped sample compared to only 30% in no doped sample. The improvement of the cycle stability was thought to be due to $Mn^{3+}$ ion decrease as the Al doping from the XPS analysis results.

• Journal of the Korean Geotechnical Society
• /
• v.17 no.4
• /
• pp.289-299
• /
• 2001

본 연구는 균질 및 2개층 비균질지반에서 사질토지반 상에 놓인 정방형 기초의 극한지지력과 침하에 대하여 고찰하였다. 본 연구는 얕은기초의 거동에 대한 정방형 기초의 크기, 지반 상대밀도, 기초 폭에 대한 상부층의 두께 비(H/B), 상부층 아래 경계면의 경사($\theta$) 그리고 지반강성비의 영향을 규명하기 위하여 모형실험을 수행하였다. 동일 상대밀도에서 지지력 계수($N_{{\gamma}}$)는 일정하지 않으며 기초 폭에 직접적으로 관련되며 지지력계수는 기초 폭이 증가함에 따라 감소하였다. 기초크기의 영향과 구속압력의 영향을 고려하는 Ueno 방법에 의한 극한지지력의 예측값은 고전적인 지지력 산정식보다 더 잘 일치하며 그 값은 실험값의 65% 이상으로 나타났다. $\theta$=$0^{\circ}$인 2개층 지반의 결과에 근거하여, 극한지지력에 대한 하부층 지반의 영향을 무시할 수 있는 한계 상부층 두께는 기초 폭의 2배로 결정되었다. 그러나, 73%의 상부층 상대밀도인 경우는 침하비($\delta$B) 0.05 이하에서만 이 결과가 유효하였다. 경계면이 경사진 2개층 지반의 결과에 근거하여, 상부층의 상대밀도가 느슨할수록 그리고 상부층의 두께가 클수록 극한지지력에 대한 경계면 경사의 영향은 크지 않는 것으로 나타났다. 경계면의 경사가 증가함에 따른 극한침하량의 변화는 경계면이 수평인 경우($\theta$=$0^{\circ}$)를 기준으로 0.82~1.2(상부층 $D_{r}$=73%인 경우) 그리고 0.9~1.07(상부층 $D_{r}$=50%인 경우) 정도로 나타났다.Markup Language 문서로부터 무선 마크업 언어 문서로 자동 변환된 텍스트를 인코딩하는 경우와 같이 특정한 응용 분야에서는 일반 문자열에 대한 확장 인코딩 기법을 적용할 필요가 있을 수 있다.mical etch-stop method for the etching of Si in TMAH:IPA;pyrazine solutions provides a powerful and versatile alternative process for fabricating high-yield Si micro-membranes. the RSC circle, but also to the logistics system in the SLC circle. Thus, the RSLC model can maximize combat synergy effects by integrating the RSC and the SLC. With a similar logic, this paper develops "A Revised System of Systems with Logistics (RSSL)" which combines "A New system of Systems" and logistics. These tow models proposed here help explain several issues such as logistics environment in future warfare, MOE(Measure of Effectiveness( on logistics performance, and COA(Course of Actions) for decreasing mass and increasing velocity. In particular, velocity in logistics is emphasized.

• Journal of Navigation and Port Research
• /
• v.40 no.1
• /
• pp.7-14
• /
• 2016

Although the life jacket can provide the buoyance with the drowner, heat loss can make the drowned individual be subject to the hypothermia. In this study, The thermal insulation of two types life jacket including inflatable and foam type were evaluate by both experiments and numerical analysis. To estimate the thermal resistance of the jackets, experiments on the heat flux were conducted by the thermal manikin exposed to cold water. Heat flux loss on the surface of thermal manikin were measured for both foam and inflatable type life jacket. Also, finite element method is applied to a body section in order to understand the level of hypothermia of each life jacket. The segmental of human thigh is represented by a multi-layered section which considers the heat conduction within tissue, bone and fat. As a result, the thermal resistance and hypothermia time of each jackets have been compared based on the finite element analysis. It was found that the insulation ability of suggested life jackets is better than that of conventional type.