• 한국자동차공학회논문집
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• 제20권4호
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• pp.125-132
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• 2012

Urea-SCR system, which converts nitrogen oxides to nitrogen and water in the presence of a reducing agent, usually AdBlue urea solution, is known as one of the powerful NOx reduction systems for mobile as well as stationary applications. For its consistent and reliable operation in mobile applications, such various problems as transient injection, ammonia slip, and freezing in cold weather have to be resolved. In this work, therefore, numerical study on three-dimensional unsteady heating problems were analyzed to understand the melting and heat transfer characteristics such as urea liquid volume fraction, temperature profiles and generated natural convection behavior in urea solution by using the commercial software Fluent 6.3. After validating by comparing numerical and experimental data with pure gallium melting phenomena, numerical experiment for urea melting is conducted with three different coolant heating models named CH1, 2, and 3, respectively. Finally, it can be found that the CH3 model, in which more coolant is concentrated on the lower part of the urea tank, has relatively better melting capability than others in terms of urea quantity of $1{\ell}$ for start-up schedule.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2003년도 학술발표대회 발표논문초록집
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• pp.80-80
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• 2003

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by motor, cognitive, and psychiatric symptoms, accompanied by marked cell death in the striatum and cortex. Stereotaxic injection of quinolinic acid (QA) into striatum results in a degeneration of GABAergic neurons and exhibits abnormal motor behaviors typical of the illness. The objective of this study was carried out to obtain basic information about whether parthenogenetic mouse embryonic stem (PmES) cells are suitable for cell replacement therapy of HD. To establish PmES cell lines, hybrid F1 (C57BL/6xCBA/N) mouse oocytes were treated with 7% ethanol for 5 min and cytochalasin-B for 4 hr to initiate spontaneous cleavage. Thus established PmES cells were induced to differentiate using bFGF (20ng/ml) followed by selection of neuronal precursor cells for 8 days in N2 medium. After selection, cells were expanded at the presence of bFGF (20 ng/ml) for another 6 days, then a final differentiation step in N2 medium for 7 days. To establish recipient animal models of HD, young adult mice (7 weeks age ICR mice) were lesioned unilaterally with a stereotaxic injection of QA (60 nM) into the striatum and the rotational behavior of the animals was tested using apomorphine (0.1mg/kg, IP) 7 days after the induction of lesion. Animals rotating more than 120 turns per hour were selected and the differentiated PmES cells (1$\times$10$^4$cells/ul) were implanted into striatum. Four weeks after the graft, immunohistochemical studies revealed the presence of cells reactive to anti-NeuN antibody. However, only a slight improvement of motor behavior was observed. By Nissl staining, cell mass resembling tumor was found at the graft site and near cortex which may explain the slight behavioral improvement. Detailed experiment on cell viability, differentiation and migration explanted in vivo is currently being studied.

• 디자인학연구
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• 제19권3호
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• pp.93-104
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• 2006

When the design profession started, design targets were mainly static hardware centered products. Due to the development of network and digital technologies, new products with dynamic and software-hardware hybrid interactive characteristics have become one of the main design targets. To accomplish the new projects, designers are required to learn new methods, tools and theories in addition to the traditional design expertise of visual language. One of the most important tools for the change is effective and rapid prototyping. There have been few researches on educational framework for interactive product or system prototyping to date. This paper presents a new model of educational contents and methods for interactive digital product prototyping, and it's application in a design curricula. The new course contents, integrated with related topics such as physical computing and tangible user interface, include microprocessor programming, digital analogue input and output, multimedia authoring and programming language, sensors, communication with other external devices, computer vision, and movement control using motors. The final project of the course was accomplished by integrating all the exercises. Our educational experience showed that design students with little engineering background could learn various interactive digital technologies and its' implementation method in one semester course. At the end of the course, most of the students were able to construct prototypes that illustrate interactive digital product concepts. It was found that training for logical and analytical thinking is necessary in design education. The paper highlights the emerging contents in design education to cope with the new design paradigm. It also suggests an alterative to reflect the new requirements focused on interactive product or system design projects. The tools and methods suggested can also be beneficial to students, educators, and designers working in digital industries.

• 전기학회논문지
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• 제66권5호
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• pp.757-764
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• 2017

As the reduction of greenhouse gases(GHGs) emission has become a global issue, the microgrid markets are growing rapidly. With the sudden changes in the market, Korean government suggested a new business model called 'Self-Sufficient Energy Islands'. Its main concern is a stand-alone microgrid composed of Distributed Energy Resources(DERs) such as Renewable Energy Sources(RESs), Energy Storage System(ESS) and Fuel Cell, in order to minimize the emission of GHGs. According to these trend, this paper is written to propose an optimal sizing method of DERs in a stand-alone microgrid by using Genetic Algorithm(GA), one of the representative stochastic methods. It is to minimize the net present cost with the variables, size of RESs and ESS. In the process for optimization, the sunless days are considered as additional constraints. Through the case study analysis, the size of DERs installed in a microgrid system has been computed using the proposed method in MATLAB. And the result of MATLAB is compared with that of HOMER(Hybrid Optimization of Multiple Energy Resources), a well-known energy modeling software.

• Journal of Biosystems Engineering
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• 제33권4호
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• pp.260-268
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• 2008

Optical diffuse reflectance sensing has potential for rapid and reliable on-site estimation of soil properties. For good results, proper calibration to measured soil properties is required. One issue is whether it is necessary to develop calibrations using samples from the specific area or areas (e.g., field, soil series) in which the sensor will be applied, or whether a general "factory" calibration is sufficient. A further question is if specific calibration is required, how many sample points are needed. In this study, these issues were addressed using data from 42 paddy fields representing 14 distinct soil series accounting for 74% of the total Korean paddy field area. Partial least squares (PLS) regression was used to develop calibrations between soil properties and reflectance spectra. Model evaluation was based on coefficient of determination ($R^2$) root mean square error of prediction (RMSEP), and RPD, the ratio of standard deviation to RMSEP. When sample data from a soil series were included in the calibration stage (full information calibration), RPD values of prediction models were increased by 0.03 to 3.32, compared with results from calibration models not including data from the test soil series (calibration without site-specific information). Higher $R^2$ values were also obtained in most cases. Including some samples from the test soil series (hybrid calibration) generally increased RPD rapidly up to a certain number of sample points. A large portion of the potential improvement could be obtained by adding about 8 to 22 points, depending on the soil properties to be estimated, where the numbers were 10 to 18 for pH, 18-22 for EC, and 8 to 22 for total C. These results provide guidance on sampling and calibration requirements for NIR soil property estimation.

• 한국항행학회논문지
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• 제4권2호
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• pp.103-113
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• 2000

유연체 부착물을 갖는 인공위성의 수학적 모델링에 관한 방법은 몇 가지들이 있다. 본 논문에서는 FEM에 비해 차수가 낮아 계산시간을 줄일 수 있는 근사화 방법중 하나인 추측모드법을 사용한 하이브리드 라그랑지 방정식을 유도하였다. 이것들은 각속도에 관한 세개의 식들과 유연변위에 관한 두개의 식들로 이루어지며, 위성 본체와 태양전지판의 상호작용을 표현한다. 자세제어에 있어서, 제어법칙은 제어입력뿐만 아니라 진동억제를 포함한 성능지수를 최소화하도록 설계하였다. 이 목적을 위해 본 논문은 LQG와 LQG/LTR 제어기를 사용하였고, 결과로는 진동억제를 고려한 소각선회 성능을 보여준다. 특히, 본 논문에서는 특이시스템을 특이값 분리에 의한 비특이시스템 가정법을 통한 LQG/LTR 설계를 보여준다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권23호
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• pp.10057-10059
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• 2015

Positron emission tomography (PET) as the functional component of current hybrid imaging (like PET/CT or PET/MRI) seems to dominate the horizon of medical imaging in coming decades. $^{18}$Flourodeoxyglucose ($^{18}FDG$) is the most commonly used probe in oncology and also in cardiology and neurology around the globe. However, the major capital cost and exorbitant running expenditure of low to medium energy cyclotrons (about 20 MeV) and radiochemistry units are the seminal reasons of low number of cyclotrons but mushroom growth pattern of PET scanners. This fact and longer half-life of $^{18}F$ (110 minutes) have paved the path of a centralized model in which $^{18}FDG$ is produced by commercial PET radiopharmacies and the finished product (multi-dose vial with tungsten shielding) is dispensed to customers having only PET scanners. This indeed reduced the cost but has limitations of dependence upon timely arrival of daily shipments as delay caused by any reason results in cancellation or rescheduling of the PET procedures. In recent years, industry and academia have taken a step forward by producing low energy, table top cyclotrons with compact and automated radiochemistry units (Lab-on-Chip). This decentralized strategy enables the users to produce on-demand doses of PET probe themselves at reasonably low cost using an automated and user-friendly technology. This technological development would indeed provide a real impetus to the availability of complete set up of PET based molecular imaging at an affordable cost to the developing countries.

• 정보관리학회지
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• 제31권3호
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• pp.249-270
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• 2014

전체 학술지 논문 가운데 오픈액세스(Open Access, OA)가 차지하는 비중은 현재 20%-30%에 이르고 있고, 최근에는 출판 즉시 오픈액세스가 가능한 골드 OA에 대한 관심이 높다. 이 연구는 골드 OA를 출판하기 위한 선결 조건인 '논문 처리 수수료(Article Processing Charges, APC)' 지원에 관한 것으로 연구후원기관과 저자의 재직대학에서 어떠한 정책을 수립하여 실천하고 있는지를 알아보았다. 영국을 비롯한 유럽에서는 수년 동안 연구후원기관의 APC 부담에 관한 타당성 검토와 시범사업을 진행하여 왔고, 현재 본격적으로 시행하고 있는 단계이다. 미국을 비롯한 북미에서는 주요 대학도서관을 중심으로 OA 펀드를 조성하여 APC를 지원하고 있다. 반면에 한국은 연구후원기관과 대학에서 논문의 그린 OA를 추진할 뿐, APC를 지원하여 골드 OA를 출판하는 단계에 이르지 못하고 있다. 주제 분야에 따라 다르지만 국제 학술지에 논문을 출판하는 국내 연구자도 적지 않아 이들의 논문이 골드 OA로 출판된다면 국제적인 파급력은 크게 증진될 전망이다. 이에 국내 연구후원기관과 대학도 골드 OA에 관심을 갖고 OA 전문 학술지와 하이브리드 학술지에서 요구하는 APC를 지원하는 방향으로 정책의 기본 틀을 세우려는 노력을 경주해야 할 것으로 보인다.

• 한국경영과학회지
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• 제41권3호
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• pp.75-96
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• 2016

This paper investigates the usefulness of drones in an urban delivery system. We define the vehicle and drone routing problem with time window (VDRPTW) and present a model that can describe a dual mode delivery system consisting of drones and vehicles in the metropolitan area. Drones are relatively free from traffic congestion but have limited flight range and capacity. Vehicles are not free from traffic congestion, and the complexity of urban road network reduces the efficiency of vehicles. Using drones and vehicles together can reduce inefficiency of the urban delivery system because of their complementary cooperation. In this paper, we assume that drones operate in a point-to-point manner between the depot and customers, and that customers in the need of fast delivery are willing to pay additional charges. For the experiment datasets, we use instances of Solomon (1987), which are well known in the Vehicle Routing Problem society. Moreover, to mirror the urban logistics demand trend, customers who want fast delivery are added to the Solomon's instances. We propose a hybrid evolutionary algorithm for solving VDRPTW. The experiment results provide different useful insights according to the geographical distributions of customers. In the instances where customers are randomly located and in instances where some customers are randomly located while others form some clusters, the dual mode delivery system displays lower total cost and higher customer satisfaction. In instances with clustered customers, the dual mode delivery system exhibits narrow competition for the total cost with the delivery system that uses only vehicles. In this case, using drones and vehicles together can reduce the level of dissatisfaction of customers who take their cargo over the time-window. From the view point of strategic flexibility, the dual mode delivery system appears to be more interesting. In meeting the objective of maximizing customer satisfaction, the use of drones and vehicles incurs less cost and requires fewer resources.

• 시스템엔지니어링학술지
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• 제12권1호
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• pp.73-87
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• 2016

Combining power generation and water production by desalination is economically advantageous. Most desalination projects use fossil fuels as an energy source, and thus contribute to increased levels of greenhouse gases. Environmental concerns have spurred researchers to find new sources of energy for desalination plants. The coupling of nuclear power production with desalination is one of the best options to achieve growth with lower environmental impact. In this paper, we will per-form a sensitivity study of coupling nuclear power to various combinations of desalination technology: {1} thermal (MSF [Multi-Stage Flashing], MED [Multi-Effect Distillation], and MED-TVC [Multi-Effect Distillation with Thermal Vapour Compression]); {2} membrane RO [Reverse Osmosis]; and {3} hybrid (MSF-RO [Multi-Stage Flashing & Reverse Osmosis] and MED-RO [Multi-Effect Distillation & Reverse Osmosis]). The Korean designed reactor plant, the APR1400 will be modeled as the energy production facility. The economical evaluation will then be executed using the computer program DEEP (Desalination Economic Evaluation Program) as developed by the IAEA. The program has capabilities to model several types of nuclear and fossil power plants, nuclear and fossil heat sources, and thermal distillation and membrane desalination technologies. The output of DEEP includes levelized water and power costs, breakdowns of cost components, energy consumption, and net saleable power for any selected option. In this study, we will examine the APR1400 coupled with a desalination power plant in the Kingdom of Saudi Arabia (KSA) as a prototypical example. The KSA currently has approximately 20% of the installed worldwide capacity for seawater desalination. Utilities such as power and water are constructed and run by the government. Per state practice, economic evaluation for these utilities do not consider or apply interest or carrying cost. Therefore, in this paper the evaluation results will be based on two scenarios. The first one assumes the water utility is under direct government control and in this case the interest and discount rate will be set to zero. The second scenario will assume that the water utility is controlled by a private enterprise and in this case we will consider different values of interest and discount rates (4%, 8%, & 12%).