• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.136-144
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• 2010

Exhaust gas recirculation (EGR) is an emission control technology allowing significant NOx emission reduction from light-and heavy duty diesel engines. The future EGR type, dual loop EGR, combining features of high pressure loop EGR and low pressure loop EGR, was developed and optimized by using a commercial engine simulation program, GT-POWER. Some variables were selected to control dual loop EGR system such as VGT (Variable Geometry Turbocharger)performance, especially turbo speed, flap valve opening diameter at the exhaust tail pipe, and EGR valve opening diameter. Applying the dual loop EGR system in the light-duty diesel engine might cause some problems, such as decrease of engine performance and increase of brake specific fuel consumption (BSFC). So proper EGR rate (or mass flow) control would be needed because there are trade-offs of two types of the EGR (HPL and LPL) features. In this study, a diesel engine under dual loop EGR system was optimized by using design of experiment (DoE). Some dominant variables were determined which had effects on torque, BSFC, NOx, and EGR rate. As a result, optimization was performed to compensate the torque and BSFC by controlling start of injection (SOI), injection mass and EGR valves, etc.

• Journal of Preventive Medicine and Public Health
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• v.46 no.2
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• pp.74-81
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• 2013

Objectives: The objective of this study was to evaluate the performance of risk-adjusted mortality models for colorectal cancer surgery. Methods: We investigated patients (n=652) who had undergone colorectal cancer surgery (colectomy, colectomy of the rectum and sigmoid colon, total colectomy, total proctectomy) at five teaching hospitals during 2008. Mortality was defined as 30-day or in-hospital surgical mortality. Risk-adjusted mortality models were constructed using claims data (basic model) with the addition of TNM staging (TNM model), physiological data (physiological model), surgical data (surgical model), or all clinical data (composite model). Multiple logistic regression analysis was performed to develop the risk-adjustment models. To compare the performance of the models, both c-statistics using Hanley-McNeil pair-wise testing and the ratio of the observed to the expected mortality within quartiles of mortality risk were evaluated to assess the abilities of discrimination and calibration. Results: The physiological model (c=0.92), surgical model (c=0.92), and composite model (c=0.93) displayed a similar improvement in discrimination, whereas the TNM model (c=0.87) displayed little improvement over the basic model (c=0.86). The discriminatory power of the models did not differ by the Hanley-McNeil test (p>0.05). Within each quartile of mortality, the composite and surgical models displayed an expected mortality ratio close to 1. Conclusions: The addition of clinical data to claims data efficiently enhances the performance of the risk-adjusted postoperative mortality models in colorectal cancer surgery. We recommended that the performance of models should be evaluated through both discrimination and calibration.

• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.3
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• pp.273-279
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• 2013

The objective of this study is to find out a reason why prescriptions have different effects on each patient who has same symptoms or same abdominal examinations and further more to classify the formulas more efficiently. In applying 's prescriptions, it is known that conventional ways such as treatment in accordance with symptoms or abdominal examinations have many advantages and problems reversely. To make up for the problems, additional references like strength of constitutional resistance and location of disease, degree of income and outgo are designed. And the notion in Oriental Medicine embracing aspects mentioned above corresponds to triple energizer. Triple energizer's exuberance-debilitation is able to draw an inference from some factors like density of skin interstices, elasticity of abdomen, appetite, digestive power. According to Exuberance-Debilitation of Triple Energizer, can be divided into five steps: weak(弱)-moderately weak(中弱)-neither weak nor strong(中)-moderately strong(中强)-strong(强). prescriptions would be dealt with those 5 steps, and it would be highly effective and consequently side effects could be reduced. On the basis of this classification method upon formula group, the prescriptions of can be applied more accurately by setting a direction through strength of constitutional resistance and location of disease and combining with existing references like symptoms, palpation and abdominal examinations.

• Journal of Korean Society of Rural Planning
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• v.13 no.2
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• pp.133-142
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• 2007

Tourism and recreation spots in Korea have been developed metropolitan cities-oriented that facility construction has too much importance in local tourist site development more than satisfaction and experience. Tourism hardly seems to play its role as a motive power even in locals where tourism occupies much in their economic development. Therefore, the ministry of culture & tourism has introduced a plan to discover cultural and tourism resources as a development alternative which handles theme-ability and specialization. However, most projects of local tourism resources developed since 1999 have resulted similar features comparing to previous and existing tourist spots. And the main objectives of this paper have not been realized very well. This research hence forth suggests a program-based model development in tourism resources, with a case study of Gokun-gugok, one of the historical and cultural sites and is located in Hwachon-gun, Gangwon Province. Main points include: Since the Gokun-gugok landscape has been undermined and been loosed the traditional cultural value due to the road development, this study intends to plan to make the adventure of tourism destination including restoring the site as a cultural place. The Gokun-gugok site needs to develop combining various types of tours and adventures with instructive and educational programs to meet the visitors' needs. This research also intends to precede a development plan based on harmonizing natural, historical and cultural assets of the Gokun-gugok with facility maintains and tourism development. Meanwhile, the study stresses on realizing development of tourism resources categorizing programs by seasonality, visitor's economic class, and visit duration. Asa consequence, the research presents a "Culture & Tourism Academy" which deals with these types of adventure programs and informative educations. To assess feasibility of the development plan in terms of economy, environment and policy, the research conducted the site inspection and examined the site's surroundings, land properties and inundation. 145,000 square meters have been extracted as a feasible development area out of total 392,500 square meters. Finally, the study segmentizes target markets basedon the result of the survey on visitors and local residents. The more segmentized markets employ facilities according to their traditional characters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.8
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• pp.1490-1494
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• 2006

Most network equipment is an embedded system designed to execute specific function. An embedded system is an electronic control system mixing hardware and software to execute only fixed function for the purpose of system, not confuter, performing diverse function for a wide use. Early embedded system executed only simple function, combining specific function with optimization, a micro size, and low power, but it has developed to meet complex and diverse system. The purpose of this study is to realize DHCP server based on embedded system. To achieve this, embedded Linux was ported in ez Bord-M01 mounted with Intel Strong ARM SA1110 processor, and ethernet-based network was constructed for network function. In this way, this study suggests embedded DHCP server where Window and Linux client hosts are dynamically configurated as network information by dynamically assigning network information in embedded board.

• Journal of KIISE:Software and Applications
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• v.28 no.9
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• pp.681-687
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• 2001

In order to raise a class discrimination power by combining multiple classifiers under the Bayesian decision theory, the upper bound of a Bayes error rate bounded by the conditional entropy of a class variable and decision variables obtained from training data samples should be minimized. Wang and Wong proposed a tree dependence first-order approximation scheme of a high order probability distribution composed of the class and multiple feature pattern variables for minimizing the upper bound of the Bayes error rate. This paper presents an extended high order product approximation scheme dealing with higher order dependency more than the first-order tree dependence, based on the minimization of the upper bound of the Bayes error rate. Multiple recognizers for unconstrained handwritten numerals from CENPARMI were combined by the proposed approximation scheme using the Bayesian formalism, and the high recognition rates were obtained by them.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.287-293
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• 2011

This paper investigates the applicability of a piezoelectric cantilever for energy supply of wireless sensor node used in structural health monitoring of bridges. By combining the constitutive equation of piezoelectric material and the dynamic equation of cantilever structure, the coupled governing equation for cantilever equipped piezoelectric patches has been addressed in matrix form. Forced excitation tests were carried out to validate the numerical model and to investigate the power output characteristics of the energy harvester. From the numerical simulation based on the measured bridge accelerations under KTX, Saemaul, Mugunghwa trains, the peak powers generated from the device were found to be 28.5 mW, 0.65 mW, 0.51 mW respectively. It is revealed from the results that bridge vibrations caused by moving loads is not a practical source for energy harvesting because of its low acceleration level, low frequency and short duration.

• Biomolecules & Therapeutics
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• v.26 no.4
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• pp.409-416
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• 2018

Vasicinone, a quinazoline alkaloid from Adhatoda vasica Nees. is well known for its bronchodilator activity. However its anti-proliferative activities is yet to be elucidated. Here-in we investigated the anti-proliferative effect of vasicinone and its underlying mechanism against A549 lung carcinoma cells. The A549 cells upon treatment with various doses of vasicinone (10, 30, 50, $70{\mu}M$) for 72 h showed significant decrease in cell viability. Vasicinone treatment also showed DNA fragmentation, LDH leakage, and disruption of mitochondrial potential, and lower wound healing ability in A549 cells. The Annexin V/PI staining showed disrupted plasma membrane integrity and permeability of PI in treated cells. Moreover vasicinone treatment also lead to down regulation of Bcl-2, Fas death receptor and up regulation of PARP, BAD and cytochrome c, suggesting the anti-proliferative nature of vasicinone which mediated apoptosis through both Fas death receptors as well as Bcl-2 regulated signaling. Furthermore, our preliminary studies with vasicinone treatment also showed to lower the ROS levels in A549 cells and have potential free radical scavenging (DPPH, Hydroxyl) activity and ferric reducing power in cell free systems. Thus combining all, vasicinone may be used to develop a new therapeutic agent against oxidative stress induced lung cancer.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.6
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• pp.662-673
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• 2008

Two hybrid receptor models, potential source contribution function (PSCF) and concentration weighted tracjectory (CWT), were compared for locating $PM_{2.5}$ sources contributing to the atmospheric $PM_{2.5}$ concentrations in Seoul. The source contribution estimates by chemical receptor model (CMB) receptor model were used to identify better source areas, Among the sources, soil, agricultural burning, marine aerosol, coal-fired power plant and Chinese aerosol were only considered for the study because these sources were more likely to be associated with the long-range transport of air pollutant. Both methods are based on combining chemical data with calculated air parcel backward trajectories. However, the PSCF analyses were performed with trajectories above the $75^{th}$ percentile criterion values, while the CWT analyses used all trajectories. This difference resulted in locating of different sources, which might be helpful to interpret locating of $PM_{2.5}$ sources, High possible source areas in source contribution of soil and agricultural burning contributing to the Seoul $PM_{2.5}$ were inland areas of Heibei and Shandong provinces (highest density areas of agricultural production and population) in China. The "Chinese aerosol" was used as a representative source for the $PM_{2.5}$ originated from urban area in China. High possible source areas for the aerosol were the cities in China where are relatively close to the receptor. This result suggests that Chinese aerosol is likely to be a useful tool in studies on source apportionment and identification in Korea.

• Journal of Biomedical Engineering Research
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• v.29 no.2
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• pp.99-106
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• 2008

To improve $B_1$ homogeneity in high field MRI, the RF power is applied to the transmit array coil elements sequentially in the time-multiplexed way. Since only a single coil element is activated in a time-multiplexing slot, the global standing wave formation in the human body is greatly suppressed. The time-multiplexing slot width is on the order of micro seconds, hence, high-order-harmonic slices can be placed far from the transmit coil and simultaneous multiple slice selection can be avoided. The $B_1$ homogeneities of a birdcage coil and an eight-channel transmit array coil have been compared through finite difference time domain simulations. The simulation results indicate that the proposed technique can reduce the peak-to-peak $B_1$ inhomogeneity down to one fourth of the transmission with a birdcage coil on the central plane of the human head model at 3 T. The mimicking experiments at 3 T, eight separate experiments with a single coil element activated and image reconstruction by combining the eight images, also show promising results. It is expected that the proposed technique has some advantages over other $B_1$ improving methods in real practice since simple RF switching circuitries are only necessary and electromagnetic coupling between the coil elements is out of concern in its realization.