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Comparison of PSA and VSA processes for air separation (공기 분리를 위한 O2 PSA (Pressure Swing Adsorption)공정과 VSA (Vacuum Swing Adsorption) 공정의 설게 및 성능 비교)

  • Lee, Sang Jin;Ahn, Hyungwoong;Jee, Jeung-Geun;Kim, Min-Bae;Moon, Jong-Ho;Bae, Yoon-Sang;Lee, Chang-Ha
    • Clean Technology
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    • v.10 no.2
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    • pp.101-109
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    • 2004
  • PSA and VSA processes have been used broadly to produce oxygen from ambient air in midium- or small-sized plants. PSA and VSA processes are the separation methods which use difference of amount adsorbed as pressure is changed periodically, but they have the differences in pressurization and regeneration. In this study, the performance of 6-step PSA process was compared with that of 5-step VSA process with respect to purity and recovery. In addition, the effects of each step (pressurization step, adsorption step, and pressure equalization step) on purity and recovery were investigated. As a result, the VSA process using zeolite 10X showed better performance than the zeolite 5A PSA and zeolite 13X VSA process in comparison with purity, recovery and productivity. And it was enough to apply the vacuum pressure of 200 torr for the VSA, which produced over 90% oxygen with 70% recovery.

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Synthesis and Characterization of Sm2O3 Doped CeO2 Nanopowder by Reverse Micelle Processing (역마이셀을 이용한 Sm2O3 도핑 CeO2 나노분말의 합성 및 특성)

  • Kim, Jun-Seop;Bae, Dong-Sik
    • Korean Journal of Materials Research
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    • v.22 no.4
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    • pp.207-210
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    • 2012
  • The preparation of $Sm_2O_3$ doped $CeO_2$ in Igepal CO-520/cyclohexane reverse micelle solutions has been studied. In the present work, we synthesized nanosized $Sm_2O_3$ doped $CeO_2$ powders by reverse micelle process using aqueous ammonia as the precipitant; hydroxide precursor was obtained from nitrate solutions dispersed in the nanosized aqueous domains of a micro emulsion consisting of cyclohexane as the oil phase, and poly (xoyethylene) nonylphenylether (Igepal CO-520) as the non-ionic surfactant. The synthesized and calcined powders were characterized by Thermogravimetry-differential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD), and Transmission electron microscopy (TEM). The crystallite size was found to increase with increase in water to surfactant (R) molar ratio. Average particle size and distribution of the synthesized $Sm_2O_3$ doped $CeO_2$ were below 10 nm and narrow, respectively. TG-DTA analysis shows that phase of $Sm_2O_3$ doped $CeO_2$ nanoparticles changed from monoclinic to tetragonal at approximately $560^{\circ}C$. The phase of the synthesized $Sm_2O_3$ doped $CeO_2$ with heating to $600^{\circ}C$ for 30 min was tetragonal $CeO_2$. This study revealed that the particle formation process in reverse micelles is based on a two step model. The rapid first step is the complete reduction of the metal to the zero valence state. The second step is growth, via reagent exchanges between micelles through the inter-micellar exchange.

Model Construction of Sexual Adjustment of Patients with Spinal Cord Injury (척수장애인의 성적적응과 관련요인에 관한 모형구축)

  • Kang, Hyun-Sook;Koh, Jung-Eun;Shu, Yeon-Ok
    • Journal of Korean Academy of Nursing
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    • v.30 no.4
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    • pp.1018-1034
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    • 2000
  • The purpose of this study was to construct model of sexual adjustment in people with spinal cord injury and to determine factors that relate to sexual adjustment using methodological triangulation. A total of 134 persons who were registered members of spinal cord injury organization and admitted rehabilitation unit in the hospital were included in the study. Participants answered questionnaire concerning importance of life events, sexual concern, sexual adjustment. Qualitative data were collected through semi-structured indepth interviews from 10 individuals with spinal cord injury who were previously included in the quantitative study. Constant compatative method was used to analyze the data. The results were as follows : 1) With respect to eleven other areas of life, sex life ranked the sixth and economic status ranked the highest in terms of importance. However social life ranked the lowest among the 11areas. 2) Among seven topics related to sexuality were methods and techniques to achieve sexual satisfaction, and helping a partner cope emotionally with limitation on sexual dysfunction was the second greastest. 3) The mean score for sexual adjustment was 19.47 which can be considered. 4) A process on how individuals with spinal cord injury adjust to their changed sexual life immerged from the qualitative data. It includs 4 stages: 'stage of loss' 'stage of endeavoring' 'stage of effort' and 'stage of adjustment'. Categories showing context for the action/interaction strategies were 'steadiness' and 'rediscovery as a sexual being'. There were three factors which may stimulate the adjustment process while the others may interrupt it. Those factors included personal matters, family matters and social matters. The individuals may follow each stage step by step but may go back to the previous step depending on the outcomes of their adjustment. 5) There were three factors which may stimulate the adjustment process while the others may interrupt it. Those factors included personal matters, family matters and social matters.

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A Pre-Resource Reservation Mechanism using NSIS protocol (NSIS 프로토콜을 이용한 사전자원예약 방안)

  • Kim, Sun-Young;Byun, Hae-Sun;Lee, Mee-Jeong
    • Journal of KIISE:Information Networking
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    • v.35 no.6
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    • pp.538-548
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    • 2008
  • In the Internet Engineering Task Force(IETF), Next Step in Signaling(NSIS) working group, proposed a mechanism to discover the Crossover Node(CRN), when the route is changed by Mobile Node(MN) handover. The CRN is divergence or convergence node on old and new path for reserving resources. Trough the CRN discovery mechanism, it possible to reduce a signaling delay and avoid the redundant reservation on the common path between old and new path. However, the QoS(Quality of Service) can be guaranteed continuously while the MN is performing handover, it is needed to pre-reserve the resource on the new path before completion of the handover. When the nodes on the new path try to make a pre-resource reservation before the handover, it is difficult to pre-reserve the resource with the existing CRN discovery mechanism. Therefore, we proposed a Passive CRN(PCRN) discovery scheme and pre-resource reservation mechanism. The PCRN which means an initial common point between the current reserved and the new paths, where the handover can take place.

Extension of the Site Binding Model for Ion Sensing Mechanism of ISFET and Its Application to the Hydrogen Ion Sensing $Si_3N_4$ Membrane (ISFET 이온감지기구의 Site Binding 모형 확장과 그 $Si_3N_4$ 수소이온 감지막에의 적용)

  • Seo, Hwa-Il;Kwon, Dae-Hyuk;Lee, Jong-Hyun;Sohn, Byung-Ki
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.11
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    • pp.1358-1366
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    • 1988
  • The dual dielectric films have been grown on single-crystalline silicon substrates with the thickness ranging from 125A to 180A at various gas and temperature conditions by using rapid thermal process that included independent nitridation step. The film characteristics and their dependence on the contents of the hydrochloric gas and the processing time have been studied. By the addition of the hydrochloric gas, the initial oxide thickness was significantly changed, but after sequential nitridation processes the thickness of the films was nevertheless a little bit varied within 10A. All the samples of the dual dielectric films show the increased breakdown voltages in proportion to the additive contents of the hydrochloric gas and also show the higher breakdown strengths than the thermal oxide and nitrided oxide films grown by the conventional furnance process or the rapid thermal nitridation process that was composed of the dependent nitridation cycles.

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Effects of the Contents of Hydrochloric Gas on the Electrical Properties of the RTO/RTN Dual Dielectric Films (HCI 첨가에 의한 RTO/RTN 이중 절연박막의 전기적 특성 변화)

  • Kim, Youn-Tae;Park, Sung-Ho;Bae, Nam-Jin;Kim, Bo-Woo;Ma, Dong-Sung
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.11
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    • pp.1350-1357
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    • 1988
  • The dual dielectric films have been grown on single-crystalline silicon substrates with the thickness ranging from 125A to 180A at various gas and temperature conditions by using rapid thermal process that included independent nitridation step. The film characteristics and their dependence on the contents of the hydrochloric gas and the processing time have been studied. By the addition of the hydrochloric gas, the initial oxide thickness was significantly changed, but after sequential nitridation processes the thickness of the films was nevertheless a little bit varied within 10A. All the samples of the dual dielectric films show the increased breakdown voltages in proportion to the additive contents of the hydrochloric gas and also show the higher breakdown strengths than the thermal oxide and nitrided oxide films grown by the conventional furnance process or the rapid thermal nitridation process that was composed of the dependent nitridation cycles.

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The Activities of Childhood Cancer Foundation in Taiwan (대만 어린이암재단의 활동)

  • Lee ChungHsiang
    • Korean Journal of Hospice Care
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    • v.2 no.1
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    • pp.182-192
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    • 2002
  • Childhood Cancer Foundation of ROC(CCFROC) has been founded since 1982. Its goal is to provide comprehensive care for cancer children and their families. And in turn, under the provision of good and complete care, they can be back to the school and society. To achieve this goal, it needs to get every body's effort of the society together. The foundation has been founder under this concept and tried to fulfil this task. The first step is to educate the public to know that childhood cancer can be cured and the process of treatment is long and expensive. In order to reach this life-saving procedure, campaigns for raising money is most important thing. Then, pediatric hematologists / oncologists try to organize study group, named Taiwan Pediatric Qncology Goupp(TPOG), to make treatment protocols for childhood cancers. Its primary purpose is to increase the cure rate to prove the earlier the diagnosis and treatment, the better the prognosis. The second step is to provide full support of medical expenses and further to give help for emergent need to living. Through the varieties of active exercises of cancer children or families, foundation provides opportunities for them to share the experience during the different periods of diseases. The third step is to extend the scope of training activities for many kinds of personnel who devote to the care for cancer children. On the other hand, it promotes the cooperation or communication with international organizations and sets up recreation playing ground in the communities. The aim is to provide a comprehensive and integrated care for cancer children during their education, breeding and even accomplishment period. Besides the financial support of medical care, it provides social services to give psychological support for children and their families, to strengthen doctor-patients or doctor-families relationship. The foundation provides the mourning religious activities to cherish the memory of their children who passed away and to comfort their sadness. Since the childhood cancer is curable, its treatment should be active, comprehensive and it needs to provide to all cancer children without exception. Indeed, the work of CCFROC should be changed according to the environment and different time period. But, it needs the full support from the society. We hope the scope and content of the work will be more extended and its achievement will be better than now in the future.

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Characteristics of Two-Step Plasma-Assisted Boronizing Process in an Atmosphere of BCl3-H2-Ar (BCl3-H2-Ar 분위기를 이용한 2단계 플라즈마 보로나이징 특성)

  • Nam, Kee-Seok;Lee, Gu-Hyun;Shin, Pyung-Woo;Song, Yo-Seung;Kim, Bae-Yeon;Lee, Deuk-Yong
    • Journal of the Korean Ceramic Society
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    • v.43 no.6 s.289
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    • pp.358-361
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    • 2006
  • A two-step plasma-assisted boronizing process was carried out on the AISI 1045 steel substrate to reduce the pore density introduced by a conventional single plasma boronizing process. The specimens were plasma boronized for 1 h at $650^{\circ}C$ and subsequently far 7 h at $800^{\circ}C$ in an atmosphere of $BCl_3-H_2-Ar$. The boride layer thickness was parabolic in boronizing time, a high HV reading of 1540 was found up to the boride layer thickness of $25{\mu}m$. It was found that the morphology of the boride layer prepared by the two-step boronizing process was changed from a columnar to a tooth-like structure and the pores in the borided steel were eliminated completely in comparison to those synthesized by the conventional single boronizing process, implying that it is highly applicable for enhancing the dense and compact coating properties of the low-alloy steel.

Study on the hydrogen production using the metal oxide (Cu-ferrite) (금속산화물(Cu-ferrite)를 이용한 수소제조 연구)

  • Park, Chu-Sik;Seo, In-Tai;Kim, Jung-Min;Lee, Sang-Ho;Hwang, Gap-Jin
    • Journal of Hydrogen and New Energy
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    • v.15 no.3
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    • pp.201-207
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    • 2004
  • Redox characteristics of metal oxide for hydrogen production by thermochemical water-splitting were investigated. $CuFe_2O_4$ as a redox pair that had a different molar ratio of Cu and Fe were prepared by co-precipitation method. Hydrogen production consisted of water-splitting step and thermal reduction step was performed below 1200K. Redox characteristics of Cu-ferrites were studied using the thermal gravimetric analysis technique. Also, structure change of Cu-ferrite during thermal reduction was investigated using the high temperature controlled XRD. In results, oxygen release of Cu-ferrite during the thermal reduction was initiated at oxygen site combined with Cu. Consequently, oxygen release amount of Cu-ferrite was increased with increase of Cu molar ratio of Cu-ferrite. It was found that thermal reduction of Cu-ferrite was begun at $875^\circ{C}$. It was confirmed that structure of Cu-ferrite was changed to metal and cation excess metal oxide during the thermal reduction step.

Suitability of Setting Summer Indoor Temperature for Thermal Comfort (여름철 실내 쾌적온도 설정 기준의 적합성)

  • Shim, Huen Sup;Jeong, Woon Seon
    • The Korean Journal of Community Living Science
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    • v.24 no.4
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    • pp.583-589
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    • 2013
  • This study was to provide the information for optimum utilization of the air-conditioning system in the human health and energy saving perspective. Subjects were 17 male and female college students(7 males and 10 females) with normal weight. They wore a short sleeved shirt, knee length trousers, socks, and underwear(0.4clo). They were asked to choose the preferred temperature from different environmental temperatures($28^{\circ}C$, $25^{\circ}C$). The physiological responses were measured and the subjective sensation was voted during the step changes of environmental temperature, starting at $28^{\circ}C$ to $25^{\circ}C$ with $1^{\circ}C$ decrease every 20 minutes. The preferred temperature was $25.9{\pm}0.4^{\circ}C$ for males and $26.9{\pm}0.2^{\circ}C$ for females at $28^{\circ}C$ and $24.8{\pm}0.6^{\circ}C$ for males and $25.6{\pm}0.1^{\circ}C$ for females at $25^{\circ}C$. The preferred temperature decreased about $1.3^{\circ}C$ while the environmental temperature changed $3^{\circ}C$. During the environmental step changes, mean skin temperature decreased more in females while the oxygen uptake and rectal temperature were kept constant for both males and females. We found the preferred temperature was affected by the exposed temperature and the thermal sensation in the condition. Subjects preferred a lower environmental temperature when they were exposed to a lower temperature with cooler sensation. Therefore, in the perspective of human health and energy saving, it is recommended to start setting the air-conditioning temperature higher than the preferred temperature.