• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.4
• /
• pp.857-864
• /
• 2009

This study aimed at developing the two stage and dual filtration system. It has a sand + activated carbon layer above the underdrain system and a sand layer above the middledrain system for pretreatment. When retrofitting an old filter bed or designing a new one, this technology can substitute the existing sand filter bed without requiring a new site. In order to extend the filtering duration, the upper layer of the filter bed consists of the rapid sand filtration with large particles which pre-treats and removes coarse particles and turbidity matters. The middle layer has biological activated carbon(BAC) and granular activated carbon(GAC) to eliminate dissolved organic matters, disinfection by-products precursors etc. The lower layer consists of the sand filtration for the post filtering mode. In this study, a pilot plant of two stage and dual filtration system was operated for 4 months in the S water treatment plant in Kyounggi-Do. The stability of turbidity was maintained below 1NTU. The TOC, THMFP and HAAFP were removed about 90% by two stage and dual filtration system, which is almost 2 times higher than S WTP. From analysis result of HPC along the depth of activated carbon + sand layer at 2nd stage, microorganism was mostly not detected, however, increment of HPC was shown as it becomes deeper. It indicates that growth of microorganism is occurred at activated carbon layer.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.4
• /
• pp.132-137
• /
• 2018

Although the number of chemical accidents has been declining since the Chemical Control Act of 2015, there have been repeated occurrences of similar types of accidents at printed circuit board (PCB) manufacturing facilities. These accidents were caused by the overflow of hydrochloric acid and hydrogen peroxide, which are toxic chemicals used in the printed circuit board manufacturing process. An analysis of the $Cl^-$ content to identify the cause of the accident showed that in the mixed route of hydrochloric acid and hydrogen peroxide, which are accidental substances, the $Cl^-$ concentration was 66.85 ppm in the hydrogen peroxide sample. Through reaction experiments, it was confirmed that the deformation of a PVC storage tank and generation of chlorine gas, which is a toxic gas, occurred due to reaction heat occurring up to $50.5^{\circ}C$. This paper proposes a facility safety management plan, including overcharge, overflow prevention, leak detection device, and separation tank design for mixing prevention in printed circuit board manufacturing facility etch process. To prevent the recurrence of accidents of the same type, the necessity of a periodic facility safety inspection and strengthening of the safety education of workers was discussed.

• Journal of Digital Contents Society
• /
• v.18 no.7
• /
• pp.1377-1386
• /
• 2017

We propose a smart ocean meteorological observation system which is capable of real-time measurement of vulnerable marine climate and oceanographic conditions. Besides, imported products have several disadvantages such that they can't be measured for a long time and can't transmit data in real time. In the proposed system, smart ocean observation digging system, it observes real-time ocean weather with data logger methods. Furthermore, we also use existing dataloggers functions with various sensors which are available in the ocean at the same time. Also, we applied the Kalman-filter algorithm to the ocean crest measurement to reduce the noise and increase the accuracy of the real-time wave height measurement. In the experiment, we experimented the proposed system with our proposed algorithms through calibration devices in the real ocean environment. Then we compared the proposed system with and without the algorithms. As a result, the system developed with a lithium iron phosphate battery that can be charged by a system used in the ocean and minimized power consumption by using an RTC based timer for optimal use. Besides, we obtained optimal battery usage and measured values through experiments based on the measurement cycle.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.34 no.2
• /
• pp.322-328
• /
• 2007

The first molar is important for mastication and also it plays roles to formation of vertical occlusion and growth of jaw bone after mixed dentition. Impaction of mandibular first molar can result in a short lower facial height, formation of a follicular cyst, pericoronal inflammation, resorption of the roots of neighboring teeth and malocclusion. The options of treatment plans are as follows; observation, surgical exposure, orthodontic traction, surgical relocation and extraction. Surgical exposure could be considered as a basic treatment plan. For surgical exposure it is important to maintain patent channel between the crown and the normal eruptive path into the oral cavity, many techniques including cementation of a celluloid crown, packing with zinc oxide-eugenol surgical pack are used. In these cases, we could observe spontaneous eruption of mandibular first molar using surgical exposure with or without removal of odontoma. Also we could obtain the main patency effectively and conveniently by using surgical pack and translucent retainer.

• Journal of Animal Environmental Science
• /
• v.14 no.1
• /
• pp.53-60
• /
• 2008

This study was carried out to measure and analyze the vibration levels and modes produced by a hopper type feeder used at laying hen farms, to prevent the vibration resonance and to reduce the vibration of the hopper type feeder (6-tier). The most vibration in a layer house were produced by hopper type feeder as shown the previous study. According to the measurement results, the ratio of transmissibility was as high as 100-638% for natural frequency of 170 Hz or less. And vibration simulations were taken by the results of vibration mode analysis and the weakest points to vibrations were determined accordingly. Then measurement and analysis were taken for those points. The quantities of vibration were 4.6354-4.9118 g($g=9.81^m/s^2$) by axis. In this study, it was found that hopper type feeder generated vibration as much as to influence the ratio of laying eggs of layer. And by the analysis of vibration on the weakest points, design methods and equipment were suggested for isolating/reducing of vibration by each axis.

• Journal of Advanced Navigation Technology
• /
• v.18 no.1
• /
• pp.35-43
• /
• 2014

In this paper, it is about to non-contact wireless power transmission according to various conditions of self induction principle between the two planar coils at a transmission unit and a receiving unit based on the theory of wireless power transmission. The experiments are occurred in order to power transfer of noncontact method from designed wireless circuits in the primely coil and secondary coil, and the applying to Half Bridge Resonant converter transmission unit and receiving unit. and that were able to prepared circumstance to calculate of the output voltage and power source. The main power of the inductive coupling the resonant converter at the transmission unit is converted electrical energy using the solar cell module and artificial light source (halogen lamp) as a replace light and received 24 V power supply from solar power was used a input power source for the wireless power transmission device. Experimental results, to received of power is used to illuminate the lighting and to charge the battery in receiving circuit.And the wireless power transmission efficiency measured at the output side of the transmission unit is obtained about 70% to 89% compared to input power of receiving unit.In addition, efficiency were tested through ID verification method and comparing the phase difference between the voltage when foreign substances interfere with wireless power transmission.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2002.11a
• /
• pp.63-63
• /
• 2002

현재 기계적 합금화법에서는 주로 합금을 구성하는 성분원소 분말을 불활성분위기에서 볼밀처리 함으로써 함금화를 시키거나 모합금에 산화물을 분산시켜 복합화시키는 공정을 통하여 각종 화합물, 비정질상 및 과포화고용체등의 준안정상의 합성 뿐만이 아니라 초미세조직의 생성에 관한 폭 넓은 분야의 연구가 행하여지고 있다. 한편 MA에서는 볼멀처리중 기계적 에너지의 투여에 의하여 실제 반응온도보다 낮은 온도에서 발생하는 특이한 화학반응 즉 Mechanochemical 반응을 일으키 기도 한다. 본 연구에서는 헤마타이트($Fe_20_3$)와 금속윈소인 Ti의 MA처리에 의하여 고상환원반응 을 유기시켜 $Fe-TiO_2$계 nanocomposite 분말재료를 제조하고자 한다. 특히 MA 공정에 있어서 자기 물성의 변화와 X선 회절을 통하여 고상환원반응에 의한 복합분말의 생성과정을 조사하였다. 출발원료는 $Fe_20_3$(고순도화학제,99.9%, 평균입경 0.1$\mu\textrm{m}$)와 금속원소인 Ti(99.9%, 명균업경 150$\mu\textrm{m}$)을 몰비 2:3의 조성이 되도록 하여 MA를 실시하였다. 볼멀은 고에너지 유성형 볼밀장치(독일 제, Fritsch P-5)를 이용하였으며 진공치환형 용기에 원료분말을 장입하여 2회정도 진공배기한 후 아르곤 가스를 충전하여 볼밀을 행하였다. 얻어진 분말시료에 대하여 x-선 회절장치, 전자현미경 (SEM) 및 진동시료형자력계(VSM)를 통하여 결정구조, 미셰조직 빛 자기특성을 조사하였다. $Fe_2O_3-Ti$ 혼합분말의 MA처리 에 의하여 초기단계부터 환원반응과 함께 $Fe_3TIO_{lO}$ 중간상이 관찰 되었으나 30hrs의 MA처리 후 Fe와 산화물 $TiO_2$로 모두 환원되어 $Fe-TiO_2$계 나노복합분말이 얻어짐을 알 수 있었다. 이 때 X션 회절피크의 line broadening으로부터 복합분말의 Fe 명균 결정립 크기는 24nm로 초미세 결정럽의 분말합금이었다. 포화자화값은 볼밀처리에 따라 점점 증가하여 MA 30시간에는 20.3emu/g로 포화됨을 알 수 있었다. 또한 보자력 Hc는 MA초기단계에 350e로 매우 낮으나 30시간 후에는 Hc값이 2600e로 매우 큰 값을 나타내었다. 이것은 환원반응결과 초기에 생성된 Fe의 결정립이 비교적 크고 결정결함이 적으나 볼밀처리를 30시간까지 행하면 Fe 결정렵의 미세화 빛 strain 증가로 magnetic hardening이 일어나기 때문인 것으로 사료된다.

• Progress in Medical Physics
• /
• v.17 no.1
• /
• pp.24-31
• /
• 2006

Automated analysis software was developed to measure the magnitude of the intrafractional and interfractional errors during breast radiation treatments. Error analysis results are important for determining suitable planning target volumes (PTV) prior to Implementing breast-conserving 3-D conformal radiation treatment (CRT). The electrical portal imaging device (EPID) used for this study was a Portal Vision LC250 liquid-filled ionization detector (fast frame-averaging mode, 1.4 frames per second, 256X256 pixels). Twelve patients were imaged for a minimum of 7 treatment days. During each treatment day, an average of 8 to 9 images per field were acquired (dose rate of 400 MU/minute). We developed automated image analysis software to quantitatively analyze 2,931 images (encompassing 720 measurements). Standard deviations ($\sigma$) of intrafractional (breathing motion) and intefractional (setup uncertainty) errors were calculated. The PTV margin to include the clinical target volume (CTV) with 95% confidence level was calculated as $2\;(1.96\;{\sigma})$. To compensate for intra-fractional error (mainly due to breathing motion) the required PTV margin ranged from 2 mm to 4 mm. However, PTV margins compensating for intefractional error ranged from 7 mm to 31 mm. The total average error observed for 12 patients was 17 mm. The intefractional setup error ranged from 2 to 15 times larger than intrafractional errors associated with breathing motion. Prior to 3-D conformal radiation treatment or IMRT breast treatment, the magnitude of setup errors must be measured and properly incorporated into the PTV. To reduce large PTVs for breast IMRT or 3-D CRT, an image-guided system would be extremely valuable, if not required. EPID systems should incorporate automated analysis software as described in this report to process and take advantage of the large numbers of EPID images available for error analysis which will help Individual clinics arrive at an appropriate PTV for their practice. Such systems can also provide valuable patient monitoring information with minimal effort.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.7
• /
• pp.483-490
• /
• 2009

The aims of this study were to evaluate the removal efficiency for various pollutants in urban storm runoff by a filtration device, and to determine design parameters depending on filter media properties. Appropriate selection of filter media will affect the size and life time of the filtration device. Sets of column tests were performed in order to evaluate the removal efficiency by perlite and a synthetic resin. An investigation of surface properties including CEC (cation exchange capacity) and zeta-potential suggested that the perlite had a superior adsorption capability for cationic pollutants. TCODcr and turbidity were analyzed to investigate the removal characteristic of particulate pollutant. In both columns, the particles in the collected storm runoff was almost completely capture with a small EBCT (empty bed contact time) of 2.5 minutes. Complete clogging at the EBCT of 2.5 minutes occurred after 630 minutes in the perlite column and 810 minutes in the resin column. The removal efficiency of TCODcr and turbidity at the EBCT of 2.5 minutes decreased to below 70% due to an wall effect. The removal efficiency for dissolved pollutant (SCODcr) was negligible due to the insufficient contact time for adsorption. The removal of heavy metals (Cu, Zn, Pb) was mostly ascribed to the filtration of particles containing metals, since the relationship between CEC and the removal efficiency was not apparent. The result of this study would be valuable for the application of filtration device to control of urban storm runoff.

• Journal of Appropriate Technology
• /
• v.7 no.2
• /
• pp.127-135
• /
• 2021

To respond to the threat of global warming, countries around the world are promoting the spread of renewable energy and reduction of carbon emissions. In accordance with the United Nation's Sustainable Development Goal to combat climate change and its impacts, global automakers are pushing for a full transition to electric vehicles within the next 10 years. Electric vehicles can be a useful means for reducing carbon emissions, but in order to reduce carbon generated in the stage of producing electricity for charging, a power generation system using eco-friendly renewable energy is required. In this study, we propose a smart electric mobility operating system integrated with off-grid solar power plants established in Tanzania, Africa. By applying smart monitoring and communication functions based on Arduino-based computing devices, information such as remaining battery capacity, battery status, location, speed, altitude, and road conditions of an electric vehicle or electric motorcycle is monitored. In addition, we present a scenario that communicates with the surrounding independent solar power plant infrastructure to predict the drivable distance and optimize the charging schedule and route to the destination. The feasibility of the proposed system was verified through test runs of electric motorcycles. In considering local environmental characteristics in Tanzania for the operation of the electric mobility system, factors such as eco-friendliness, economic feasibility, ease of operation, and compatibility should be weighed. The smart electric mobility operating system proposed in this study can be an important basis for implementing the SDGs' climate change response.