• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.107-110
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• 2001

제철소에서 매년 대량 발생되어 주로 매립처분되고 있는 제강분진의 재활용 방안으로서, 폐수처리분야에 널리 사용되고 있는 펜톤산화공정의 반응촉매원인 Fe 공급원으로서 제강분 진의 활용 가능성에 대한 연구를 수행하였다. 본 연구에서는 포항제철소에서 제철부산물로 발생되는 제강분진을 전처리 없이 산화촉매로 사용하여 김포 수도권 매립지의 침출수 처리 공정에서 펜톤산화조에 유입되는 원수를 대상으로 과산화수소에 의한 산화처리 실험을 수행하였다. 반응은 회분식으로 수행하였으며, 일반적으로 알려진 펜톤산화반응의 주요 반응조 건인 운전 pH, 과산화수소 주입량 및 분할주입, 제강분진의 주입량 등의 변화에 따른 각 조 건별 시간에 따른 반응결과를 알아보았다. 또한 기존의 Fe 공급원으로 사용되고 있는 FeSO$_4$와 처리성능 및 적용조건에 대한 비교 실험도 수행하였다. 침출수 수질변화는 TOC (Total Organic Carbon) analyzer를 사용하여 측정한 TOC값으로 나타냈으며, pH controller 와 정량펌프를 사용하여 HCl과 NaOH주입을 통해 반응기간동안 일정 pH를 유지하였다. 본 연구결과, 최적 pH 조건인 4에서 최대 75% TOC 제거율을 나타내었으며, 대부분의 반응은 30분 이내에 이루어졌다. 주어진 실험조건에서 FeSO$_4$와 비교하여 반응속도와 처리효율에서 향상된 결과를 나타내었으며 반응 후 응집침전실험에서도 보다 높은 처리효과를 얻을 수 있었다. 결론적으로, 과산화수소/제강분진 시스템을 이용한 화학적 산화처리방법은 경제성과 처리성능에서 기존의 펜톤산화공정의 대체방안으로서 향 후 적용가능성이 높을 것으로 기대된다.g, 200 mg/kg, 300 mg/kg의 순서로 함량이 점차 감소하는 결과를 얻을 수 있었다. 이상의 결과를 종합하여 볼 때 가자 메탄올추출물은 PQ 유도독성을 신장 및 폐조직에서 효과적으로 경감시키는 것으로 나타났다.ted retailers ("sellers") must accept end-of-life items returned to them by the consumers. At the local level, Taipei City implements a pay-as-you-throw program, whereby citizens pay waste collection and treatment fees through the purchase of special trash bags approved by the Taipei City Government. However. recyclables that are separated by citizens are collected free-of-charge by the City. Taichung City and Kaohsiung City, on the other hand, enforce mandatory sorting schemes, whereby citizens face penalties if they don't separate recyclables from the trash before pick-up. These programs have resulted in a significant reduction in municipal waste. Per capita waste collected per day has dropped from 1.143

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.6
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• pp.293-303
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• 2008

As the computing environment moves to the wireless and handheld system, the power efficiency is getting more important. That is the case especially in the embedded hand-held system and the power consumed by the memory system takes the second largest portion in overall. To save energy consumed in the memory system we can utilize low power mode of SDRAM. In the case of RDRAM, nap mode consumes less than 5% of the power consumed in active or standby mode. However hardware controller itself can't use this facility efficiently unless the operating system cooperates. In this paper we focus on how to minimize the number of active units of SDRAM. The operating system allocates its physical pages so that only a few units of SDRAM need to be activated and the unnecessary SDRAM can be put into nap mode. This work can be considered as a generalized and system-wide version of PAVM(Power-Aware Virtual Memory) research. We take all the physical memory into account, especially buffer cache, which takes an half of total memory usage on average. Because of the portion of buffer cache and its importance, PAVM approach cannot be robust without taking the buffer cache into account. In this paper, we analyze the RAM usage and propose power-aware page allocation policy. Especially the pages mapped into the process' address space and the buffer cache pages are considered. The relationship and interactions of these two kinds of pages are analyzed and exploited for energy saving.

• Journal of Internet of Things and Convergence
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• v.6 no.2
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• pp.45-50
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• 2020

In this paper, we propose a QoS-based handover management scheme in SDN. Even though there have been lots of recent services such as IoT, the conventional networks provide a monolitic handover method without considerations on flow-specific QoS features. For example, the conventional Internet provides a handover method which only considers IP continuity. On the other hand, 4G and 5G networks use a strict handover method for all kinds of flows with resource reservations. This means that it is difficult to guarantee the QoS requirements for the flow with a strict QoS requirement in Internet and the inefficient resource utilization can occur in the 4G and 5G because of the strict QoS-based handover management. The proposed scheme proposes the flow handover management scheme based on QoS requirements according to the SDN controller's management. From the network operators' perspective, the proposed scheme can provide the efficient resource utilization as well as QoS provisioning.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.2
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• pp.7-12
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• 2014

Government has recently restricted heating and cooling set temperatures for the commercial and public buildings due to increasing national energy consumption. The goal of this paper is to visualize a future two way indoor set temperature control impact on building energy consumption by using TRNSYS simulation modeling. The building was modelled based on the twin test cell with the same dimension. Air source ground coupled heat pump performance data has been used for modeling by TRNSYS 17. Daejeon weather data has been used from Korea Solar Energy Society. The heating set temperature in the reference room is $24^{\circ}C$ as well as the target room set temperature are $23^{\circ}C$, $22^{\circ}C$, $21^{\circ}C$ and $20^{\circ}C$. The cooling set temperature of the reference room is also $24^{\circ}C$ as well as the target room set temperature of $25^{\circ}C$, $26^{\circ}C$, $27^{\circ}C$ and $28^{\circ}C$. For the air source heat pump system, heating season energy consumption is $35.52kWh/m^2y$ in the reference room. But the heating energy consumption in the target room is reduced to 7.5% whenever the set temperature decreased every $1^{\circ}C$. The cooling energy consumption in the reference room is $4.57kWh/m^2y$. On the other hand, the energy consumption in the target room is reduced to 22% whenever the set temperature increased every $1^{\circ}C$ by two way controller. For the geothermal heat pump system, heating energy consumption in the reference room is reduced to 20.7%. The target room heating energy consumption is reduced to 32.6% when the set temperature is $22^{\circ}C$. The energy consumption in the target room is reduced to 59.5% when the set temperature is $26^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.351-358
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• 2016

An Electrical Point Machine (NS:New-type Switch), which is equipped and operated at railways in Korea, has been used since the 1960s after being imported from Japan. On the other hand, although the mechanical configuration has improved the position motor control circuit, the electrical connection has not been improved, so NS may have a problem, such as the interlocking system of automatic train operation. In addition, NS is the most vulnerable part in the railway system and a huge train accident may occur due to minor defects. The existing NS wiring set of the circuit controller should be checked only if fixed. Therefore, an excessive inspection time only by a Railroad Signal expert is required. In this paper, the improvement of electrical connection in a NS wiring set, such as the position motor control circuit, was developed and the prototype was installed at Seoul Metro in the distance to go section. The results can be used to help make appropriate adjustments. The improvement of the NS wiring set enhance the maintenance efficiency, passenger service and the stability of the signal system as well as reducing the maintenance cost.

• Journal of the Korea Computer Graphics Society
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• v.27 no.2
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• pp.1-11
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• 2021

In a virtual environment, a 3D workspace and 3D interaction are possible, but most virtual reality applications use a 2D color picker. This paper implements a 3D color picker based on 3D color space in a virtual environment, and compares color selection performance with the existing 2D color picker. The 3D color picker is intuitive by using the 3D color space as it is, and it can position the 3D pointer at a specific point in the color space using a controller, which is a virtual reality device, so a user can select a color in one step. On the other hand, the 2D color picker has the advantage of being familiar with existing users who work with colors in a computer environment, but has a disadvantage that requires several steps of user interaction since it has to set color properties through 2D interfaces. Based on user experiments, we confirmed the usefulness of a 3D color picker in addition to a 2D color picker in a virtual environment, and it was possible to perform natural 3D work in a virtual environment using the 3D color picker.

• Journal of Korea Entertainment Industry Association
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• v.15 no.4
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• pp.349-357
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• 2021

Recently, drones are rapidly becoming common and expanding. There is a great need for diversity in whether drone flight data can be used as entertainment technology analysis data. In particular, it is necessary to check whether it is possible to analyze and utilize the flight and operation process of entertainment drones, which are developing through autonomous and intelligent methods, through data analysis and machine learning. In this paper, it was confirmed whether it can be used as a machine learning technology by using FC data in the evaluation of drones for entertainment. As a result, FC data from DJI and Parrot such as Mavic2 and Anafi were unable to analyze machine learning for entertainment. It is because data is collected at intervals of 0.1 second or more, so that it is impossible to find correlation with other data with GCS. On the other hand, it was found that machine learning technologies can be applied in the case of Fixhawk, which used an ARM processor and operates with the Nuttx OS. In the future, it is necessary to develop technologies capable of analyzing the characteristics of entertainment by dividing fixed-wing and rotary-wing flight information. For this, a model shoud be developed, and systematic big data collection and research should be conducted.

• International Journal of Ocean System Engineering
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• v.2 no.3
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• pp.185-194
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• 2012

A Macroscopic combination of two or more distinct materials is commonly referred to as a "Composite Material", having been designed mechanically and chemically superior in function and characteristic than its individual constituent materials. Composite materials are used not only for aerospace and military, but also heavily used in boat/ship building and general composite industries which we are seeing increasingly more. Regardless of the various applications for composite materials, the industry is still limited and requires better fabrication technology and methodology in order to expand and grow. An example of this is that the majority of fabrication facilities nearby still use an antiquated wet lay-up process where fabrication still requires manual hand labor in a 3D environment impeding productivity of composite product design advancement. As an expert in the advanced composites field, I have developed fabrication skills with the use of machinery based on my past composite experience. In autumn 2011, the Korea government confirmed to fund my project. It is the development of a composite sanding machine. I began development of this semi-robotic prototype beginning in 2009. It has possibilities of replacing or augmenting the exhaustive and difficult jobs performed by human hands, such as sanding, grinding, blasting, and polishing in most often, very awkward conditions, and is also will boost productivity, improve surface quality, cut abrasive costs, eliminate vibration injuries, and protect workers from exposure to dust and airborne contamination. Ease of control and operation of the equipment in or outside of the sanding room is a key benefit to end-users. It will prove to be much more economical than normal robotics and minimize errors that commonly occur in factories. The key components and their technologies are a 360 degree rotational shoulder and a wrist that is controlled under PLC controller and joystick manual mode. Development on both of the key modules is complete and are now operational. The Korean government fund boosted my development and I expect to complete full scale development no later than 3rd quarter 2012. Even with the advantages of composite materials, there is still the need to repair or to maintain composite products with a higher level of technology. I have learned many composite repair skills on composite airframe since many composite fabrication skills including repair, requires training for non aerospace applications. The wind energy market is now requiring much larger blades in order to generate more electrical energy for wind farms. One single blade is commonly 50 meters or longer now. When a wind blade becomes damaged from external forces, on-site repair is required on the columns even under strong wind and freezing temperature conditions. In order to correctly obtain polymerization, the repair must be performed on the damaged area within a very limited time. The use of pre-impregnated glass fabric and heating silicone pad and a hot bonder acting precise heating control are surely required.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.3-4
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• 2000

Many researchers are interested in the synthesis and characterization of carbon nitride and diamond-like carbon (DLq because they show excellent mechanical properties such as low friction and high wear resistance and excellent electrical properties such as controllable electical resistivity and good field electron emission. We have deposited amorphous carbon nitride (a-C:N) thin films and DLC thin films by shielded arc ion plating (SAIP) and evaluated the structural and tribological properties. The application of appropriate negative bias on substrates is effective to increase the film hardness and wear resistance. This paper reports on the deposition and tribological OLC films in relation to the substrate bias voltage (Vs). films are compared with those of the OLC films. A high purity sintered graphite target was mounted on a cathode as a carbon source. Nitrogen or argon was introduced into a deposition chamber through each mass flow controller. After the initiation of an arc plasma at 60 A and 1 Pa, the target surface was heated and evaporated by the plasma. Carbon atoms and clusters evaporated from the target were ionized partially and reacted with activated nitrogen species, and a carbon nitride film was deposited onto a Si (100) substrate when we used nitrogen as a reactant gas. The surface of the growing film also reacted with activated nitrogen species. Carbon macropartic1es (0.1 -100 maicro-m) evaporated from the target at the same time were not ionized and did not react fully with nitrogen species. These macroparticles interfered with the formation of the carbon nitride film. Therefore we set a shielding plate made of stainless steel between the target and the substrate to trap the macropartic1es. This shielding method is very effective to prepare smooth a-CN films. We, therefore, call this method "shielded arc ion plating (SAIP)". For the deposition of DLC films we used argon instead of nitrogen. Films of about 150 nm in thickness were deposited onto Si substrates. Their structures, chemical compositions and chemical bonding states were analyzed by using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and infrared spectroscopy. Hardness of the films was measured with a nanointender interfaced with an atomic force microscope (AFM). A Berkovich-type diamond tip whose radius was less than 100 nm was used for the measurement. A force-displacement curve of each film was measured at a peak load force of 250 maicro-N. Load, hold and unload times for each indentation were 2.5, 0 and 2.5 s, respectively. Hardness of each film was determined from five force-displacement curves. Wear resistance of the films was analyzed as follows. First, each film surface was scanned with the diamond tip at a constant load force of 20 maicro-N. The tip scanning was repeated 30 times in a 1 urn-square region with 512 lines at a scanning rate of 2 um/ s. After this tip-scanning, the film surface was observed in the AFM mode at a constant force of 5 maicro-N with the same Berkovich-type tip. The hardness of a-CN films was less dependent on Vs. The hardness of the film deposited at Vs=O V in a nitrogen plasma was about 10 GPa and almost similar to that of Si. It slightly increased to 12 - 15 GPa when a bias voltage of -100 - -500 V was applied to the substrate with showing its maximum at Vs=-300 V. The film deposited at Vs=O V was least wear resistant which was consistent with its lowest hardness. The biased films became more wear resistant. Particularly the film deposited at Vs=-300 V showed remarkable wear resistance. Its wear depth was too shallow to be measured with AFM. On the other hand, the DLC film, deposited at Vs=-l00 V in an argon plasma, whose hardness was 35 GPa was obviously worn under the same wear test conditions. The a-C:N films show higher wear resistance than DLC films and are useful for wear resistant coatings on various mechanical and electronic parts.nic parts.