• Korean Security Journal
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• no.44
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• pp.169-198
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• 2015

The purpose of present study is to provide an efficient 'Disaster Emergency Communication System' (below DECS) to deal with serious disaster situations in national levels. Currently, DECSs such as the VHF, UHF, and TRS are worked to control some disaster situations in the world. However, new system such as for sending the correct image and big data is more likely to need than current the DECSs in the comtemporary societies. Several serious disaster events such as the Sam-Poong Department Store Collapse, Daegu Subway Fire, and Sewol Submerge event, nevertheless, there was not the DECS based on the field in South Korea. In July 2014, finally, South Korean government started to provide a PS-LTE system which is the new and one system with fire fighting, police, army, railway. however, there are no many academic studies for DECSs to deal with disaster situations in South Korea. The present research highlights to explore an efficient DECS of Korean styles to fix some national security and public safety. The paper provides three key findings: first is how to make a unified Korean DECS based on PS-LTE. Second is how to make sure the frequency of 700MHz levels to communicate in the shady areas. Three is what kinds of communication facility is adequate for fixing PS-LTE DECS.

• Polymer(Korea)
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• v.30 no.3
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• pp.266-270
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• 2006

Poly [(dimethylmethylyinyl) siloxane] phosphineoxide (PMViSPO) was prepared by adding phosphorus oxychloride $(POCl_3)$ to poly (dimethylmethylyinyl) siloxane (PMViS) at $0^{\circ}C$ under nitrogen atmosphere. Cadmium selenide (CdSe) was prepared by reacting cadmium oxide (CdO), tetradecyl-phosphonic acid (TDPA), trioctylphosphine oxide (TOPO) at $300^{\circ}C$, and adding solution of dissolved Se to tributylphosphine (TBP) and trioctylphosphine (TOP) CdSe-poly [(dimethylmethylvinyl) siloxane] phosphine-oxide (CdSe-SPO) adduct was synthesised by adding PMViSPO to CdSe solution. Liquid silicone rubber composite (LSRC-1) was prepared by compounding $\alpha,\omega-vinyl$ poly (dimethylsiloxane) (VPMS), $\alpha,\omega-hydrogen$) poly(dimethylsiloxane) (HPMS), and CdSe under Pt catalyst, and also LSRC-2 was prepared from VPMS, HPMS, and CdSe-SPO using Pt catalyst. It was confirmed that CdSe nanoparticles with photoluminescence characteristics was dispersed uniformly in LSR matrix. The diameter of CdSe was $30\sim50nm$. By measuring the number of CdSe nanoparticles, 202 particles of CdSe in LSRC-2 and 165 particles of CdSe in LSRC-1 were dispersed in the same area of LSR matrix. Thermal stability for LSRC-2 compounded with CdSe-SPO was better than LSRC-1.

• Journal of Korean Society of Transportation
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• v.21 no.5
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• pp.49-58
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• 2003

The Transport policies in Korea have been planned and implemented as a part of a larger economy policy based on the achievement of economic growth. As a result, previous transport policies have been focused mostly on the supply of transport infrastructure. The average annual economic growth of six percent and a twelve percent growth in motor vehicles until the late 90s led to the acceleration of the imbalance between the supply and demand of infrastructure. As such, there is a need to establish an innovative transportation policy in order to increase national competitiveness and provide momentum for national growth in the Twenty one century. This research has developed strategies and policies based on interviews that were carried out with specialists in transport field. Moreover, some transport policies have been established for the year 2020 through the conducting of a survey. The survey was conducted by interviewing respondents on making the priority of transport policies. which was then analyzed using the Data Envelopment Analysis with ranked voting data. The results are as follows. The most urgent matter was considered to be the development of a inter-modal transport system, followed by an integrated service system for public transport, and the need to increase the competitiveness of the transport and logistics industries and to further transport safety. Meanwhile, the provision of transportation for disabled people as well as the elderly was considered to be less important in Korea than in welfare nations. This stems from the belief as further attention needs to be paid to the construction of a public transport system, the establishment of transportation networks construction in preparation for reunification and the North-East Asian era, as well as the privatization of the transport infrastructure.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.765-771
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• 2019

With the increase in the speed of ships and the size of ocean structures, the importance of flow noise has become increasingly critical in meeting regulatory standards. However, unlike active investigations in aeroacoustics fields for airplanes and trains, which are based on acoustic analogy methods for tonal and broadband frequency noise, only the discrete blade passing frequency noise from propellers is considered in marine fields. In this study, prediction methods for broadband noise in marine propellers and underwater appendages are investigated using FW-H Formulation1B, which can consider the mechanism of primary noise generation of trailing edge noise. The original FW-H Formulation 1B is based on the pressure correlation function tolackitsgeneralityandaccuracy. To overcome these limitations, wall-pressure spectrum models are adopted to improve the generality in fluid mediums. The comparison of the experimental results obtained in air reveals that the proposed model exhibits a higher accuracy within 5 dB. Furthermore, the prediction procedures for broadband noise for hydrofoils are established, and the estimation of broadband noise is conducted based on the results of the computational fluid dynamics.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.4
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• pp.1-9
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• 2009

In this paper, a small area 12-bit 300MSPS CMOS Digital-to-Analog Converter(DAC) is proposed for display systems. The architecture of the DAC is based on a current steering 6+6 segmented type, which reduces non-linearity error and other secondary effects. In order to improve the linearity and glitch noise, an analog current cell using monitoring bias circuit is designed. For the purpose of reducing chip area and power dissipation, furthermore, a noble self-clocked switching logic is proposed. To verify the performance, it is fabricated with $0.13{\mu}m$ thick-gate 1-poly 6-metal N-well Samsung CMOS technology. The effective chip area is $0.26mm^2$ ($510{\mu}m{\times}510{\mu}m$) with 100mW power consumption. The measured INL (Integrated Non Linearity) and DNL (Differential Non Linearity) are within ${\pm}3LSB$ and ${\pm}1LSB$, respectively. The measured SFDR is about 70dB, when the input frequency is 15MHz at 300MHz clock frequency.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.173-180
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• 2015

A passive type of fence security system was developed, which was based on electric charge detection technique. The implemented fence security system was installed at outskirts of greenhouse laboratory in the University of Seoul. The purpose of this research is to minimize false alarms by analyzing environmental noise. The existing system determines the intrusion alarm by analyzing the power of amplified signal, but the alarm was seriously affected by natural strong wind and heavy rainfall. The SAU(Signal Analysis Unit) sends input signals to remote server which displays intrusion alarm and stores all the information in database. The environmental noise such as temperature, humidity and wind speed was separately gathered to analyze a correlation with input signal. The input signal was analyzed for frequency characteristic using FFT(Fast Fourier Transform) and the algorithm that differentiate between intrusion alarm and environmental noise signal is improved. The proposed algorithm is applied for the site for one month as the same as the existing algorithm and the false alarm data was gathered and analyzed. The false alarm number was decreased by 98% after new algorithm was applied to the fence. The proposed algorithm improved the reliability at the field regarding environmental noise signal.

• Investigative Magnetic Resonance Imaging
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• v.14 no.1
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• pp.10-20
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• 2010

Purpose : Recently, the Recon Challenge at the 2009 ISMRM workshop on Data Sampling and Image Reconstruction at Sedona, Arizona was held to evaluate feasibility of highly accelerated acquisition of time resolved contrast enhanced MR angiography. This paper provides the step-by-step description of the winning results of k-t FOCUSS in this competition. Materials and Methods : In previous works, we proved that k-t FOCUSS algorithm successfully solves the compressed sensing problem even for less sparse cardiac cine applications. Therefore, using k-t FOCUSS, very accurate time resolved contrast enhanced MR angiography can be reconstructed. Accelerated radial trajectory data were synthetized from X-ray cerebral angiography images and provided by the organizing committee, and radiologists double blindly evaluated each reconstruction result with respect to the ground-truth data. Results : The reconstructed results at various acceleration factors demonstrate that each components of compressed sensing, such as sparsifying transform and incoherent sampling patterns, etc can have profound effects on the final reconstruction results. Conclusion : From reconstructed results, we see that the compressed sensing dynamic MR imaging algorithm, k-t FOCUSS enables high resolution time resolved contrast enhanced MR angiography.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.10a
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• pp.1-2
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• 1999

시간과 공간의 구애를 받지 않는 양질의 음성, 화상, 문자정보의 교환을 위한 노력으로 디지털 휴대폰과 휴대용 컴퓨터가 등장하면서 음성과 문자정보의 교환분야에 커다란 진보를 이룩하였다. 그러나 현재는 휴대폰이 음성정보에 문자정보교환이 추가된 상황이기 때문에, 아직도 관련 정보교환기술 및 기기개발이 진행되고 있다. 앞으로 휴대폰과 휴대용 컴퓨터의 기능을 통합하고 화상정보까지 결합된 휴대용 정보기기를 위해서는 전자회로의 집적화 및 통신속도 증대가 필수적이다. 또한 이들 휴대용 정보기기를 구동시키기 위한 전력도 증가될 것으로 예측되기 때문에, 현재 전원으로 사용되는 2차전지보다 에너지 밀도가 더욱 증패된 전지가 요구될 것으로 예상된다. 그리고 내연기관의 배기에 의해 발생되는 환정오염문제를 해결하기 위한 방법중의 일환으로 전기자동차 개발이 진행되고 있으며, 이들 전기자동차에 2차전지를 장착하기 위해서 경제성이 있고, 고속충전이 가능하고, 안전성이 높은 고에너지 밀도의 2차 전지 개발이 요구되고 있다. 현재 2차전지는 음극재료나 양극재료에 따라 낚축전지, 니켈/카드륨(Ni/Cd) 전지, 니켈/수소(Ni/MH) 전지, 라륨 2 차전지등이 있으며, 전극재료의 고유특성에 의해 전위와 애너지 밀도가 결정된다. 특히 리튬 2차전지는 리튬의 낮은 산화환원전위와 분자량으로 인해 에너지 밀도가 높기 때문에 앞에서 언급한 휴대용 전자기기의 구동전원으로 많이 사용되고 있다. 리튬 2차전지는 음극 재료가 금속리튬인 경우는 리튬금속으로, 탄소재료인 경우는 리튬이온이라 하며, 한편으로 전해질이 고체 고분자이거나 혹은 역체 유기용매와 리튬염을 고분자와 혼성시킨 겔(gel)인 경우는 고분자로, 전해짙이 리튬염이 전리되어 있는 유동성 액체일 경우는 고분자를 생략하여 구분하고 있다. 즉 리튬금속 2 차전지(LB), 리튬이온 2 차전지(LIB), 리튬금속 고분자 2차전지(LPB), 리튬 이온 고분자 2차전지(LIPB)로 크게 구분된다. 금속리듐을 음극으로 사용하고 전해질로는 리튬염이 전리되어 있는 액체유기용매 를 사용한 리튬금속 2차전지는, 금속리튬전극이 충방전 과정을 반복하면서, 전리된 리튬이 균일하게 산화환원되지 못하고 표변에서 양극방향으로 성장하는 수지상 (dendrite) 현상으로 인해 안전성 확보에 문게가 있었다. 리튬과 알루미늄 합금형태로 음극에 사용한 동전형 전지는 상용화 되었지만, 이러한 단점을 개선하기 위해 리튬이온이 금속으로 석활되는 환원반응전위보다 높은 전위에서 전극재료가 충전되면서 리튬이온이 저장되고, 방전되면서 배출되는 탄소를 음극재료로, 그리고 리튬이온이 충방 전시 가역적으로 삼입 탈리되는 층상의 리튬금속산화물을 양극으로 구성하고, 엑체 전해질과 다공성 고분자 분리막을 사용한 것이 LIB이다. LIB에서 리튬이온의 이동이 가능한 액체전해질의 가능을 고분자 전해질이 대신함으로서 보다 높은 안정성을 확보 한 전지가 LIPB 이다. 또한 고분자 전해질을 사용한 경우 금속리튬상에서의 수지상 성장이 저하되는 현상이 관찰됨으로서, 이론용량이 3,860mAh/g 에 달하는 리튬금속 혹은 합금을 고분자 전지에서 음극으로 사용하고자 하는 2 차전지가 LPB 이다. 리튬 2차전지는 비록 1989년 액체전해질을 사용한 금속리튬 2차전지의 실패전력을 안고있지만 궁극적으로는 이론적으로 최대의 에너지밀도를 가지고 있는 LPB를 지 향할 것으로 예상되지만 가까운 장래에 실현되기는 어려울 것이다. 따라서 향후의 라튬 2차전지의 전개방향은 현재의 LIB를 고분자 전해질을 채용하는 LIPB로 진행시커면서 저가의 전극재료개발을 지속적으로 추진할 것으로 예상된다. 현재 리튬 2차전지는 소형전지에 국한되고 있지만 전기자동차나 전력저장용으로 이를 대형화시커기 위해서는 열적특성이 우수하고 저가인 전극재료개발이 선행되야하기 때문에, 저가의 탄소재료와 코발트산화물을 대신할 수 있는 철, 망칸 또는 니켈산 화물의 개발이 필요하다.

• Journal of Korean Society of Transportation
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• v.25 no.5
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• pp.91-100
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• 2007

This study suggests direct connection service which has advantage of high-speed operation of KTX and access convenience of general train, and Pre-feasibility studies on the direct connection service. And analyze transportation demand change by the method as follows; It is to analyze the demand change of before and after KTX operation by previous transport data of Gyeongbu line, and calculate the coefficient of utilization using triggering demand by opening the 2nd phase of Gyeongbu line (Dongdaegu${\sim}$Busan). Through Pre-feasibility analysis, reduction $70{\sim}100$ minutes of train travel time and total revenue will increase about $100 thousand per day. Also, there will be environment-friendly effects of decreasing $CO_2$ emissions. But, Direct connection service need to highly cost ; Buying and Operation cost of KTX train. Therefore, we will be get more correct result of Pre-feasibility study on direct connection service, if there are concrete on buying the KTX action plans.

• Journal of Korean Society of Transportation
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• v.25 no.5
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• pp.15-21
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• 2007

This paper proposes an improved methodology for estimating traffic accident cost savings in the transport appraisal. Four major problems from the existing framework are identified and their alternatives are suggested. First, casualties in the established approach are classified by just two types of 'killed' and 'injured'. This study supplies the indices of fatality further details. Namely, road victims are regrouped by 'killed', 'seriously injured', 'slightly injured', and 'accident reports'. Those of railways are similarly sorted by 'killed', 'seriously injured', and 'slightly injured'. Second, damage only accidents are not satisfactorily considered in the current arrangement. The accidents should be considered as one of the accident types and the social cost of them should also be evaluated. Third, the unit cost of accidents is given by the total value. The unit cost is consisted of several elements and each loss would be useful for a policy frame. This study breaks down the total figure into four pieces of costs, namely production loss, medical treatment, property loss, and administrative costs. Finally, there is inconsistency in the audit between roads and railways. Road accidents are analyzed by road types. On the other hand, patronage or others is the classification rule of rail accident costs. This paper suggests a way that the accident costs of two modes can be coherently estimated based on the level of services by each mode. The result of this study is expected to help frame more cautious social overhead capital investment policies.