• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.416-420
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• 2011

무선센서네트워크 시스템의 확산에 가장 큰 장애물인 한정된 전원으로 동작하는 특성에 따라 주기적인 배터리 교체에 소요되는 비용이다. 이러한 문제를 해결하기 위하여 원격지에서 에너지를 무선으로 공급하는 자기유지 지원 기술이 연구되고 있다. 본 논문에서는 무선에너지전송을 통해 무선센서네트워크 노드에 에너지를 전송하는 환경을 구축하고 환경에 따라 에너지 수신의 결과를 측정하는 테스트베드를 구축하였다. 구축된 테스트베드는 Powercast사의 915MHz 대역에서 3W EIRP (Equivalent Isotropic Radiated Power) 에너지 송신장치, RF (Radio Frequency) 에너지 획득 모듈 그리고 TI사의 CC2530기반의 무선센서네트워크 노드로 구성되어있다. 또한 수신된 에너지의 양을 측정하고 기록하는 LabView기반의 모니터링 시스템이 구현되었다. 구현된 테스트베드는 다양한 환경에서 RF를 기반의 무선에너지전송을 통한 자기유지(Self-sustainable) 시스템의 전원공급 상태를 모니터링에 활용될 수 있다.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.844-851
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• 2009

A soil mixture with low permeability and bentonite as an additive has been highly utilized as a cutoff material in landfills, banks, and dams. Even though it is anticipated that the water can seep through shear failures in the filter layer due to external loads and embankment loads during construction, usually only the coefficient of permeability of the soil mixture is considered rather than the changes of strength from the different amounts of additives. Therefore, the amount of bentonite was changed between 0%~4% in the soil mixture of the bed material to conduct a series of unconfined compressive strength, tensile strength, and shear strength tests on a specimen in order to study the characteristics of the strength. In the result, the unconfined compressive and tensile strength were increased along with the increased amount of bentonite in the low water content; however, the tensile strength in the consolidated-drained shear test generally showed similar values without significant changes.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.206-211
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• 1999

Mixed-bed ion exchange performance was studied experimentally with variations of cation to anion resin ratio, resin weight and temperature at ultralow sodium chloride solution concentrations of less than $1.0{\times}10^{-4}M$. Analyzing the effluent concentration histories the performance test was examined as a function of tested solution volume for a laboratory-scale continuous flow column until both the cation and anion-exchange resins were exhausted. Initial leakage was observed for both cation and anion breakthrough curves, but serious at cation breakthrough curve because of low selectivity coefficient. The slope of breakthrough curve was affected by selectivity coefficient and temperature. The slope of anion breakthrough curve was steep because of the large selectivity coefficient, and ion exchange rates increased as temperature increased. The temperature effect decreased as the total volume was increased or as the resins were exhausted.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.547-551
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• 2006

In the reactor following the American standard test method (ASTM) D5757-95 and lab-scale fluidized bed combustor, the attrition characteristics of sand and ash of Korean anthracite were investigated. The attrition characteristics, such as particle size distribution of fly ash, attrition rate, and attrition ratio etc, were studied with variation of gas velocities. The particle attrition of ash was more active than sand which was generally used as a fluidized material and also the attrition index of ash taken by ASTM D5757-95 was 5 times higher than that of sand. The formation of fine particles continuously occurred due to particle attrition with increasing gas velocities. The following equation has been suggested for attrition rate of ash. $$\frac{dW}{dt}=-3.18{\times}10^{-7}(U-U_{mf})W$$.

• Journal of The Korea Institute of Healthcare Architecture
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• v.25 no.3
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• pp.15-23
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• 2019

Purpose: As the medical laboratories in general hospitals have made an efforts on quality management and employee health, they recognized the need of design guideline for clinical laboratory. As laboratories are prohibited to patients, their environments are becoming more congested and deteriorated as time goes by. So, this study investigates the current status of facility and equipment of laboratory medicine focusing on less than three hundred patient bed hospitals, and searches the improving matters. Methods: Questionnaires to technologist captains and field surveys to medical laboratories in korean hospitals have been conducted for the data collection. 18 answers have been analysed statistically by MS Excel program. Results: The result of this study can be summarized into followings. Clinical laboratory functions are all hematology, clinical chemistry, immunology, transfusion and urine microscopy, and except for three including microbiology for infection and bio safety level. Average man power of lab are 12.3 man including lab director and captain. Patient bed number, space area and total specimen numbers are not correlated with each other, but specimen numbers and employee number are correlated with. Work space distances are usually good, but exit distances are not adequate for escape owing to obstacles. Specimen delivery system by courier, test method by automatic analyzer, access floor for exposed plumbing and electricities are more practical. Open lab layed out in the center and lab support layed peripheral in space diagram. Lab space configuration by SD method showed that lab support area and employee support area are dissatisfied. Implications: Specialized hospital and yearly total specimen numbers are related to the space area and organization for laboratory planning and design.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.2
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• pp.1-9
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• 2022

A novel steel-pipe energy pile is introduced, in which the deformed rebars for main reinforcing are replaced with steel pipes in a large diameter cast-in-place energy pile. Here, the steel pipes act as not only reinforcements but also heat exchangers by circulating the working fluid through the hollow hole in the steel pipes. Under this concept, the steel-pipe energy pile can serve a role of supporting main structures and exchanging heat with surrounding mediums without installing additional heat exchange pipes. In this study, the steel-pipe energy pile was constructed in a test bed considering the material properties of steel pipes and the subsoil investigation. Then, the thermal performance test (TPT) in cooling condition was conducted in the constructed energy pile to investigate thermal performance. In addition, the thermal performance of the steel-pipe energy pile was compared with that of the conventional large diameter cast-in-place energy pile to evaluate its applicability. As a result, the steel-pipe energy pile showed 11% higher thermal performance than the conventional energy pile along with much simpler construction processes.

• Journal of Korea Water Resources Association
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• v.53 no.7
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• pp.507-519
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• 2020

This study developed the radon measurement system that can be used for crustal movement monitoring and seismic occurrence and prediction, and compared and analyzed the results of test-operated radon measurement system and observed seismic occurrence cases. First, the developed radon measurement system consists of an NB-IoT radon measurement device, data center, data analysis, and data supply server. Because the measured radon data can be remotely trasmitted by using NB-IoT, this system is very suitable for installation and operation in unmaaned groundwater station. Second, the developed radon measurement device was test-operated at two groundwater stations in Gimpo from May to July 2019. The measured radon data was compared with the groundwater-level and electrical conductivity measurement data, and it was confirmed that the radon measurement device developed in this study has some potential for commercialization. Finally, from November 2019 to February 2020, three observed seismic cases and daily measured radon, groundwater-level, electrical conductivity data by the NB-IoT radon measurement device installed at three groundwater stations in Pohang, which is a test-bed, were compared and analyzed. As a result of the analysis, it was confirmed that the seismic occurrence correlated with radon, groundwater level, and electrical conductivity and all of these measured data will be able to provide basic data to help in seismic monitoring and prediction in the future.

• Journal of Ocean Engineering and Technology
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• v.21 no.2 s.75
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• pp.67-74
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• 2007

Maritime and Ocean Engineering Research Institute (MOERI), a branch of KORDI, has designed and manufactured a model of an autonomous underwater vehicle (AUV) named ISiMI (Integrated Submergible for Intelligent Mission Implementation). ISiMI is an AUV platform to satisfy the various needs of experimental test required for development of challenging technologies newly investigated in the field of underwater robot; control and navigational algorithms and software architectures. The main design goal of ISiMI AUV is downsizing which will reduce substantially the operating cost compared to other vehicles previously developed in KORDI such as VORAM or DUSAUV. As a result of design and manufacturing process, ISiMI is implemented to be 1.2 m in length, 0.17 m in diameter and weigh 20 kg in air. A series of tank test is conducted to verify the basic functions of ISiMI in the Ocean Engineering Basin of MOERI, which includes manual control with R/F link, auto depth, auto heading control and a final approach control for underwater docking. This paper describes the implementation of ISiMI system and the experimental results to verify the function of ISiMI as a test-bed AUV platform.

• Polymer(Korea)
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• v.32 no.4
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• pp.328-333
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• 2008

The osmotic delivery systems are based on osmosis. The transverse diffusion of water through a porous membrane from a medium with a low osmotic pressure to a medium with a high osmotic pressure. Nifedipine tablet dosage forms of Procardia $XL^{(R)}$(Pfizer) and $Adalat^{(R)}$(Bayer) are commercialized systems of this type that push-pull osmotic tablet operates successfully in delivering water-insoluble drugs. We prepared osmotic pellet system by fluidized bed coating method, and model-drug used nifedipine. The osmotic pellet system was composed of the core material. the swelling and osmotic pressure layer, the drug coating layer, and the porous membrane. This work is performed to investigate the effect of different factors, such as composition and thickness of membrane. The osmotic pellet has been successfully prepared by fluidized bed coating technology. The drug release behavior depended on the increase of CA ratio and thickness in porous membrane. The morphology of the osmotic pellet before and after the dissolution test were observed by SEM. In conclusion, we found that the drug release of osmotic pellet depended on the composition and coating thickness of porous membrane.

• Journal of Pharmaceutical Investigation
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• v.41 no.2
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• pp.67-73
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• 2011

Ion exchange resins can be one of the good carriers for sustained drug release. However, the sustained release may not be enough only with themselves and hence film coating with rate controlling polymers can be applied to have a further effect on the drug release. Due to the environmental and economic issues of organic solvent for the polymer coating, aqueous polymeric systems were selected to develop dosage forms. Among the many aqueous polymeric dispersions for the film coating, EC (ethylcellulose) based polymers such as Aquacoat$^{(R)}$ ECD and Surelease$^{(R)}$ were evaluated.A fluid-bed coating was applied as a processing method. The drug release rate was quite dependent on the coating level so the release rate could be modified easily by changing different levels of the coating. The drug release rate in the Aquacoat$^{(R)}$ coated resin particles was strongly dependent on curing, which is a thermal treatment to make homogeneous films and circumvent drug release changes during storage. After dissolution test using the compressed tablets in which the coated resin particles are contained, inhomogeneous coating and even pores could be observed showing that the mechanical properties of EC were not resistant to granulation and compaction process. However, when tablets were prepared in different batches, the release profiles were almost identical showing the feasibility of the coated resin particle as incorporated into the tablet formulation.