• Journal of Korean Society of Transportation
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• v.31 no.2
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• pp.45-59
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• 2013

This study deals with the comparative analysis between two freight demand estimation methods : Unimodal O/D based method and P/C based method. The data of access/egress truck trips has been omitted from the Korean freight unimodal O/D of KTDB. This is because KTDB's unimodal O/D has not marked the series of unlinked trips down as the whole freight intermodal transport and surveyed only the main-haul trips of them. For these reasons, freight intermodal transport mechanism has not been analysed perfectly with Korean unimodal O/D data. This study tries to estimate P/C table of Korean Import/Export container freight and develop the MCC(Multimodal Channel Choice) model. Then, comparing unimodal O/D based method and P/C based method in terms of the switch commodities between production point(the initial point of freight transport) and consumption point(the terminal point of freight transport), unimodal commodities, and commodities on links is conducted. The results show that the P/C based method is able to simulate the freight intermodal transport.

• Journal of the Korean Ceramic Society
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• v.37 no.11
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• pp.1084-1090
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• 2000

(Bi$_2$O$_2$)$^{2+}$층 사이에 두 개의 Ta-O 팔면체로 연결된 Bi 계의 층상 페로브스카이트 구조인 SrBi$_2$Ta$_2$O$_{9}$ (SBT) 박막을 XPS를 이용하여 깊이별 화학 상태 변화를 분석하였다. 아르곤 이온으로 SBT 박막을 식각하면, SBT 박막의 각 구성물들은 가속 Ar$^{+}$ 이온의 에너지에 따라 변화한다. SBT 각 구성물 중 Sr 3d의 화학 상태는 Ar$^{+}$ 이온의 에너지변화에 따라 근소하게 변화한다. 반면에, Ta 4f와 Bi 4f의 화학 상태 변화는 인가되는 Ar$^{+}$ 이온 에너지에 확실하게 의존한다. 특히, Bi 4f는 Sr과 Ta에 비해 낮은 Ar$^{+}$ 이온 에너지에서도 Bi-O의 화학 상태가 금속 Bi 화학 상태로 현저하게 변화한다. 이러한 SBT 박막의 화학 상태 변화는 산호 원자의 선택적인 식각 때문에 발생하며 선택적인 식각은 SBT 박막 내에서 각 구성물과 산소간의 질량 차이와 각 구성물의 열적 안정성에 의존함을 알 수 있다.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1740-1742
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• 2004

산소 과전압이 낮은 $MnO_2$를 촉매로 사용하여 반도체 산화물계의 산소선택성 전극을 제조하고 산화물 코팅층의 미세구조와 전기화학적 특성을 분석하였다. Ti 기판에 열분해 법을 이용하여 $MnO_2$ 피막을 형성하였고, 또한 binder를 이용한 코팅 방법을 이용하여 Ti, Fb 기판에 $MnO_2$ 피막층을 형성하였다. 450$^{\circ}C$에서 1시간 열분해하여 약 1 ${\mu}m$의 $MnO_2$ 피막층을 형성 시켰으나 Ti 기판과의 접착력이 약하여 피막자체에 대한 전기화학적 특성은 관찰할 수 없었다. PVDF : $MnO_2$의 함량비가 1:1에서 1:6 까지는 DMF의 함량에 무관하게 전극 특성이 나타나지 않았지만 20:1 이상의 조성에서는 균일한 C-V 특성을 나타냈고, 산소 발생 과전압도 약 1.4V 정도로 감소되었다. 그러나 Ti 기판의 경우 열분해법을 이용하여 제조된 전극과 같이 낮은 기판과의 접착력 때문에 $MnO_2$ 피막층의 촉매효과가 현저하게 감소하였다.

• Analytical Science and Technology
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• v.7 no.1
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• pp.1-10
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• 1994

A survey was made on detection limit, reproducibility, matrix effect, linear dynamic range and the memory effect of yttrium and europium in order to analyze rare earth elements which exist as impurities in the rare earth oxide which is raw materials of fluorescent substance. When analysing a certain amount of thulium quantitatively using inductively coupled plasma mass spectrometry, it was found that the analysis was interfered with $EuO^+$ which is one of polyatomic ions caused by plasma. As the intensity of thulium linearly proportional to the europium concentration, it was possible to the determine the actual concentration of thulium.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1276-1284
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• 1999

We have evaluated the BER's and CLP's of Wireless ATM (WATM) cells employing the concatenated FEC code with pilot symbols for fading compensation through the simulation in indoor wireless channel modeled as a Rayleigh and a Rician fading channel, respectively. The results of the performance evaluation are compared with those obtained by employing the convolutional code in the same condition. In Rayleigh fading channel, considering the maximum tolerance BER ( $10^-3$) as a criterion of the voice service, it is blown that the performance improvement of about 4 dB is obtained in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols rather than the convolutional code with pilot symbols.When the values of K parameter which means the ratio of the direct signal to scattered signal power in Rician fading channel are 6 and 10, it is shown that the performance improvement of about 4 dB and 2 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols considering the maximum tolerance BER of the voice service. Also in Rician fading channel of K=6 and K= 10, considering CLP = $10^-3$ as a criterion, it is observed that the performance improvement of about 3.5 dB and1.5 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5D
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• pp.763-769
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• 2006

Gravity Model estimates target year's distributed trips using three variables like as origin zone's trip production, destination zone's trip attraction and traffic impedance between origin zone centroid and destination zone centroid. Estimating inner zone trip by gravity model is impossible because traffic impedance of inner zone has "0" value. So till today, for estimating inner zone trips, other methods like growth factor model are used. This study proposed inner zone trip estimation method that calculates inner zone's traffic impedance using established gravity model and estimates inner zone trips by putting calculated traffic impedance into the gravity model. 1988 year's surveyed O-D as basic year's O-D, proposed method's and existing methods(growth factor method and regression model)'s estimated results of 1992 year's and 2004 year's were compared with each year's real O-D by $x^2$, RMSE, Correlation coefficient. And resulted that the proposed method is superior than other existing methods.

• Journal of the military operations research society of Korea
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• v.18 no.2
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• pp.151-166
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• 1992

In this paper, we define a problem finding a simple path that maximizes the sum of the satisfied Origin-Destination (O-D) flows between nodes covered by that path as a Maximum O-D Flow Path Problem(MODEP). We established a formulation and suggested a method finding MODEP in a directed network. The method utilizes the constraint relaxation technique and the Dual All Integer Algorithm.

• Journal of the Korea Society of Computer and Information
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• v.27 no.1
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• pp.157-166
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• 2022

In this study, The goal is to analyze the feasibility of introducing a Piggyback system that can reduce the time and cost incurred by transshipment work and improve the transportation speed when transporting complex cargo by rail. To this end, the feasibility analysis methodology is reviewed through domestic and international literature review. In order to quantitatively derive the feasibility analysis values, a transportation database was applied to develop a freight transport simulation model and a freight demand prediction model for major freight transport O-D routes with a transportation distance of 200 km or more. As a result of analyzing economic feasibility by setting the analysis period to 15 years on the premise that the Piggyback System will be introduced on major cargo transport O-D routes in 2025, the NPV value was positive and the B/C value was 1.18, indicating that the Piggyback system was economical. The proposed research method can be meaningful data for establishing transportation policies that can improve the competitiveness of railroad transportation.

• Journal of the Korean Magnetics Society
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• v.21 no.2
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• pp.56-60
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• 2011

Optical properties of $T_{0.2}Fe_{2.8}O_4$ (T = V, Cr, Mn) thin films derived from ferrimagnetic $Fe_3O_4$ were investigated by spectroscopic ellipsometry in the 1~8 eV photon-energy range. The difference in optical-absorption spectrum between the ternary compounds and $Fe_3O_4$ was analyzed based on preferable sites in spinel structure and iconicity of the doped V, Cr, and Mn ions. The observed absorption spectra from $Fe_3O_4$ and the ternary compounds can be interpreted as mainly due to charge-transfer transitions of Fe d electrons characterized by absorption structures with wide energy width. Also, the observed absorption structures with narrow energy width can be interpreted as due to crystal-field transitions between different d electron configurations of tetrahedral $Fe^{3+}(d^5)$ ion. The transitions were described in terms of spin-polarized electronic states of $Fe_3O_4$.

• Fire Science and Engineering
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• v.34 no.2
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• pp.54-63
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• 2020

Although fires caused by heat generation due to Cu₂O breeding in wire connections are well-known among fire investigators, there are few papers on the analysis and introduction of fire cases by heat generation due to Cu₂O breeding. This study analyzed fire statistics caused by heat generation in electrical connections and the phenomena and features of heat generation due to Cu₂O breeding. Then, a fire which occurred in the wire connection in a university lab by heat generation due to Cu₂O breeding was analyzed in more detail. This fire case could reach a conclusion that heat generation due to Cu₂O breeding caused a fire in the wire connection through the fire pattern investigation of fire origin, the visual investigation of wire connection, 3D CT, power-on-test, and stereoscopic microscopy, SEM and EDS analysis.