• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.2
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• pp.64-70
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• 2011

Portable artificial electronic nose (E-nose) system suffers from noisy fluctuation in surroundings such as temperature, vapor concentration, and gas flow, because its measuring condition is not controled precisely as in the laboratory. It is important to develop a simple and robust vapor recognition technique applicable to this uncontrolled measurement, especially for the portable measuring and diagnostic system which are expanding its area with the improvements in micro bio sensor technology. This study used a PDA-based portable E-nose to collect the uncontrolled vapor measurement signals, and applied the image matching algorithm developed in the previous study on the measured signal to verify its robustness and improved accuracy in portable vapor recognition. The results showed not only its consistent performance under noisy fluctuation in the portable measurement signal, but also an advanced recognition accuracy for 2 similar vapor species which have been hard to discriminate with the conventional maximum sensitivity feature extraction method. The proposed method can be easily applied to the data processing of the ubiquitous sensor network (USN) which are usually exposed to various operating conditions. Furthermore, it will greatly help to realize portable medical diagnostic and environment monitoring system with its robust performance and high accuracy.

• Journal of Chest Surgery
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• v.23 no.4
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• pp.617-621
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• 1990

A heart supplies blood of about 15, 000 liters to each human organ in a day. A normal function of heart valves is necessary to accomplish these enormous work of heart. The disease of heart valve develops to a narrowness of a closure, resulting in an abnormal circulation of blood. In an attempt to eliminate the affliction of heart valves, the operative method to replace with artificial heart valves has developed and saved numerous patients over past 30 years. This replacement operation has been performed since early 1960`s in Korea, but all the artificial heart valves used are imported from abroad with very high costs until recent years. New artificial heart valves have been developed in Korea Advanced Institute of Science and Technology since early 1980`s. The first developed valve was designed with a free-floating pyrolytic carbon disk that is suspended in a titanium cage. The design of the valve was tested in vitro, and in animals in 1987. The results from this study was that the eccentrically placed struts creates a major and minor orifice when the disc opens and stagnation of flow in the area of the minor orifice has led to valve thrombosis. In this work, the design of the valve was changed from a single - leaflet valve to double - leaflet one in order to resolve the problems observed in the first - year tests. Morphological and hemodynamic studies were made for the newly designed valves through the in vitro and in vivo tests. The design and partial materials of the artificial heart valve was improved comparing with first - year`s model. The disc in the valve was modified from single - leaflet to bi - leaflet, and the material of the cage was changed from titanium metal to silicon - alloyed pyrolytic carbon. A test was made for the valve in order to examine its mechanical performance and stability. Morphological and hemodynamic studies were made for the valve that had been implanted in tricuspid position of mongrel dogs. All the test animals were observed just before the deaths. A new artificial heart valve was designed and fabricated in order to resolve the problems observed in the old model. The new valve was verified to have good stability and high resistance to wear through the performance tests. The hemodynamic properties of the valve after implantation were also estimated to be good in animal tests. Therefore, the results suggest that the newly designed valve in this work has a good quality in view of the biocompatibility. However, valve thrombosis on valve leaflets and annulus were found. This morphological findings were in accordance with results of surface polishing status studies, indicating that a technique of fine polishing of the surface is necessary to develop a valve with higher quality and performance.

• Journal of the Korean GEO-environmental Society
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• v.17 no.3
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• pp.13-19
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• 2016

The ultrasonic waves for monitoring concrete materials have been used to investigate the setting and hardening process of concrete. This paper presents the application of bender elements for monitoring the hardening properties of Controlled Low Strength Material (CLSM) and the characterization of shear waves in CLSM according to curing time. To ensure the early age properties and flow, the CLSM consists of CSA cement, sand, silt, water, fly ash, and accelerator. In addition, three different type specimens according to fine contents are mixed. A couple of bender elements are installed at the wall of measurement cell and the CLSM specimen are prepared at the measurement cell for 28 days. Experimental results show that the resonant frequency and shear wave velocities increase with an increase in the curing time, regardless of the fine contents. Up to ten hours, the amplitudes of shear waves also increase, and the resonant frequency and shear wave velocities at the same time increase as the fine contents increase. The shear wave measurement technique using the bender elements may be effectively used to evaluate the hardening properties of CLSM along the curing time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.437-445
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• 2015

The layout of facilities, in relation to information and navigational displays, has great influence on subway satisfaction, and tend to vary depending on the types of subway platform and transit station. However, until now, few studies have covered such aspects as of yet. Starting from this viewpoint, the purpose of this study was to use an IPA analysis technique to analyze that satisfaction on the importance of facilities to aid in accessibility, such as elevators and escalators, transit amenities and information and navigational displays depending on the types of platform and transit station. To do so, we've classified 15 metropolitan stations according to types of platform and transit station and analyzed differences in user importance and satisfaction as well as improvements for platforms and transit stations of similar type. By the analysis results of this study, we've concluded that the proper selection and positioning of elevator and escalator facilities and information and navigational displays was important when designing the subway station according to platform type (separate platform) and or according to the transit station type (cross, L, T types) where pedestrian flow heavily intersected. We considered that such analysis results would be helpful in the design of new stations and the enhancement of existing stations pursuant to a new direction that minimizes user inconvenience, and that improvement items should be developed first according to the platform and transit station types, which would be helpful in enhancing the efficiency of the subway improvement cost.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.102-109
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• 2017

The high pressure pump of a diesel injection system compresses the fuel supplied at low pressure into high pressure fuel and maintains the fuel of the common rail at the required pressure level according to the engine operating conditions. The high pressure pump is required to operate normally in order to compress the fuel to a high pressure of 2000 bar during the entire lifetime of the vehicle. Consequently, a suitable design technique, material durability and high precision machining are required. In this study, the high pressure pump simulation model of a 1-plunger radial piston pump is modelled by using the AMESim code. The main simulation parameters are the displacement, flow rate and pressure characteristics of the inlet and outlet valves, cam torque characteristics, and operating characteristics of the fuel metering valve and overflow valve. In addition, the operating characteristics of the pump are simulated according to the parameter changes of the hole diameter and the spring initial force of the inlet valve. The simulation results show that the operation of the developed pump model is logically valid. This paper also proposes a simulation model that can be used for current pump design changes and new pump designs.

• Journal of Bio-Environment Control
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• v.26 no.2
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• pp.146-150
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• 2017

This research investigated the effect of photo/dark period and relative humidity during dark period on the growth and quality of water dropwort in a closed-type plant factory system. At 30 days after planting, the shoot fresh weight of water dropwort under relative humidity of 60/90%(light/dark) treatment significantly higher than that under relative humidity of 60/60% treatment. The shoot fresh weight of water dropwort increased by extending light period under relative humidity of 60/60% treatment, but 16/8h photo/dark period showed the best shoot fresh weight, followed by 20/4h and 22/2h under relative humidity of 60/90% treatment. In the relative humidity of 60/90% treatment, the tipburn occurrence was reduced under 16/8h photo/dark period condition as 1.4%, whereas it was significantly increased under 20/4h and 22/2h of relatively long light time duration as 15.5% and 30.3%, respectively. In the relative humidity of 60/60% treatment, the tipburn occurrence was 15.5% under 16/8h photo/dark period condition and those under 20/4h and 22/2h photo/dark period condition were higher than 25%. The stem hardness of water dropwort was lowest in relative humidity of 60/90% and 16/8h photo/dark period treatment. The mineral contents of leaves were decreased by extending light period, but the contents of Ca were not different significantly among the treatments except the 60/60% and 22/2h treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.335-340
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• 2010

In accordance with the increasing possibility that the new and reoccurring epidemics continuously appearing abroad flow into Korea, it is very important to evaluate the efficiency of quarantine management projects of National Quarantine Station. This study adopted the pairwise comparison approach using the analytical hierarchy process(AHP) that has been recognized with its scientific adequacy for allocating the weight, the relative importance of evaluation components. AHP technique is evaluated to be distinguished in measuring the impact by making hierarchy of, simplifying and systemizing the complicated multi-criteria decision making problems. The weights by evaluation indexes were 0.2 in the organization evaluation field and 0.8 in the service and program field. The quarantine business showed the highest value, 0.45, in the service and program field. The indexes were classified into the upper category (organization evaluation field, service and program evaluation field) and lower category (input/process/result/quarantine field, inspection field, hygiene management field, pathogenic organ investigation and monitoring field, epidemics prevention promotion/education field). The evaluation indexes that were finally selected were applied to the actual businesses in National Quarantine Station. Next, the minimum evaluation indexes were selected and so the evaluation system on the businesses in National Quarantine Station was more systemized.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1268-1272
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• 2008

Low temperature plasma applied with partial oxidation is a technique to produce synthesis gas from methane. Low temperature plasma reformer has superior miniaturization and start-up characteristics to reformers using steam reforming or CO$_2$ reforming. In this research, a low temperature plasma reformer using GlidArc discharge was proposed. Reforming characteristics for each of the following variables were studied: gas components ratio (O$_2$/CH$_4$), the amount of steam, comparison of reaction on nickle and iron catalysts and the amount of CO$_2$. The optimum conditions for hydrogen production from methane was found. The maximum Hydrogen concentration of 41.1% was obtained under the following in this condition: O$_2$/C ratio of 0.64, total gas flow of 14.2 L/min, catalyst reactor temperature of 672$^{\circ}C$, the amount of steam was 0.8, reformer energy density of 1.1 kJ/L with Ni catalyst in the catalyst reactor. At this point, the methane conversion rate, hydrogen selectivity and reformer thermal efficiency were 66%, 93% and 35.2%, respectively.

• Reproductive and Developmental Biology
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• v.32 no.1
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• pp.9-14
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• 2008

Efficient gene transfer into hematopoietic stem cells is a great tool for gene therapy of hematopoietic disease. Retrovirus have been extensively used for gene delivery and gene therapy. However, current in vitro gene transfer has some obstacles suck as induction of differentiation loss of self-renewal capacity, and down-regulation of homing efficiency for in vitro hematopoietic stem cells transplantation. To overcome these problems, we developed efficient in vitro retroviral transfer technique by direct intra-bone marrow injection (IBM). We identified effective retrovirus gene transfer in bone marrow hematopoietic cells in vitro. Two weeks after retrovirus transfer via IBM injection, we observed stable EGFP gene expression in bone marrow, lymph node, spleen, and liver cells. In addition, $6.4{\pm}2.7%$ of hematopoietic stem/progenitor cells were expressed EGFP transgene from flow cytometry analysis. Our results demonstrate that in vitro retrovirus gene transfer via IBM injection can provide a viable alternative to current or moo gene transfer approach.

• Applied Microscopy
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• v.40 no.4
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• pp.211-218
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• 2010

The mammalian ovary is innervated by sympathetic and sensory neurons which contribute to regulating several aspects of ovarian function, including blood flow, steroidogenesis and follicular development. The existence of a neural connection between central neurons and the ovary has been rarely reported, but the mechanism underlying integration of ovarian activity to broader neuroendocrine responses has not been reported. We have now used a viral transneuronal tracing technique combined with a conventional retrograde labeling procedure of CT-HRP to demonstrate that oxytocin-producing neurons of the hypothalamus are synaptically connected to the ovary. Since ovarian activity is suppressed but the activity of oxytocin neurons is increased during breast feeding. Our finding that the oxytocinergic neural connection is likely to provide a direct transsynaptic mechanism by which the central nervous system maintains the state of infertility that accompanies lactation in mammals.