• Title/Summary/Keyword: Arc Energy

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Quality Evaluation of Red seabream, Pagrus major by Chemoenzymatic Method (효소 화학적 방법에 의한 참돔, Pagrus major의 품질판정)

  • 배진한;김태진;정호진;여해경;심길보;조영제
    • Journal of Aquaculture
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    • v.17 no.3
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    • pp.167-172
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    • 2004
  • Chemoenzymatic method was used in this study to evaluate the quality of cultured red seabrim. Level of ATP related compounds, ATPase and Adenylate energy charge (AEC) well reflected changes in condition of fish. ATP level in the muscle of exercised cultured red seabream was decreased significantly during cultured period. In contrast, the level of ADP in the muscle was increased during the period. Level of ATP related compounds in the muscle of cultured red seabream without exercise didn't show significant difference compared to the exercised group. AEC value in muscle of cultured red seabream without exercise was 0.89$\pm$0.02, while AEC value of the exercised group was 0.88$\pm$0.04. ATP and AEC levels among different size of fish did not show any significant difference. AEC value in all sample was higher than 0.8, indicating that the condition of cultured fish was healthy. Activity of Mg2$^{+}$ (+Ca2$^{+}$), Mg2$^{+}$ (-Ca2$^{+}$) and Ca2$^{+}$-ATPase during culture period did not change significantly, regardless of exercise. Therefore, the AEC appears to have some validity as fish health indicator.

The Effects of Partial Substitution of Mo and Heat Treatment on the Electrode Characteristics of ZrV0.1Mn0.7Ni1.2 Hydrogen Storage alloy (Ni-MH 2차 전지용 ZrV0.1Mn0.7Ni1.2 수소저장합금의 전극특성에 미치는 Mo의 부분치환과 열처리의 영향)

  • Han, Dongsoo;Oh, Myunghark;Jeong, Chigyu;Chung, Wonsub;Kim, Ingon
    • Transactions of the Korean hydrogen and new energy society
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    • v.9 no.1
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    • pp.16-24
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    • 1998
  • Recently Zr-based $AB_2$ type hydrogen absorbing alloy has received much attention as a negative electrode material for the Ni-MH batteries because of its high capacity. In this study $ZrV_{0.1}Mn_{0.7}Ni_{1.2}$ alloy was chosen and the effects of heat treatment and a partial substitution of the Mo in Mn site on the various electrode properties were investigated. The alloys was prepared by arc melting (as-cast sample). Some of them were heat treated at $1,100^{\circ}C$ for 4 hours. After this they were differentiated by the different cooling rates of slow cooling and quenching. Various electrode characteristics such as activation process, high rate dischargeability and self discharge characteristic were investigated with the three types of electrodes. It was found that heat treated alloys resulted in an increase in plateau flatness of P-C isotherms however both discharge capacity and high rate capability were decreased. And the partial substitution of Mo for Mn in $ZrV_{0.1}Mn_{0.7}Ni_{1.2}$ alloy improved the self-discharge characteristic without the loss of discharge capacity (300mAh/g).

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Interfacial disruption effect on multilayer-films/GaN : Comparative study of Pd/Ni and Ni/Pd films

  • 김종호;강희재;김차연;전용석;서재명
    • Proceedings of the Korean Vacuum Society Conference
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    • 2000.02a
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    • pp.113-113
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    • 2000
  • 직접천이형 wide band gap(3.4eV) 반도체중의 하나인 GaN를 청색 및 자외선 laser diode, 고출력 전자장비 등으로 응용하기 위해서는 낮은 접합저항을 갖는 Ohmic contact이 선행되어야 한다. 그러나 만족할만한 p-type GaN의 Ohmic contact은 아직 실현되고 있지 못하며, 이는 GaN와 접합 금속과의 구체적인 반응의 연구를 필요로 한다. 본 연구에서 앞서 Pt, Pt, Ni등의 late transition metal을 p-GaN에 접합시킨 결과 이들은 접합 당시 비교적 평탄하나 후열 처리과정에서 비교적 낮은 온도에서 기판과 열팽창계수의 차이로 인하여 평탄성을 잃어버리면서 barrier height가 증가한다는 사실을 확인하였다. 따라서 본 연구에서는 이러한 열적 불안정성을 극복하기 위하여 Ni과 Pd를 차례로 증착하고 가열하면서 interfacial reaction, film morphology, Fermi level의 움직임을 monchromatic XPS(x-ray photoelectron spectroscopy) 와 SAM(scanning Auger microscopy) 그리고 ex-situ AFM을 이용하여 밝히고자 하였다. 특히 후열처리에 의한 계면 반응에 수반되는 구성 금속원소 간의 합금현상과 금속 층의 평탄성이 밀접한 관계가 있다는 것을 확인하였다. 이러한 합금과정에서 나타나는 금속원소들의 중심 준위의 이동을 체계적으로 규명하기 위해서 Pd1-xNix와 Pd1-xGax 합금들의 표준시료를 arc melting method로 만들어 농도에 따른 금속원소들의 중심 준위의 이동을 측정하여, Pd/Ni/p-GaN 및 Ni/Pd/p-GaN 계에서 열처리 온도에 따른 interfacial reaction을 확인하였다. 그 결과 두 계가 상온에서 nitride 및 alloy를 형성하지 않고 고르게 증착되고, 열처리 온도를 40$0^{\circ}C$에서 $650^{\circ}C$까지 증가시킴에 따라 계면반응의 부산물인 metallic Ga은 증가하고 있으마 nitride는 여전히 형성되지 않는 것을 확인하였다. 증착당시 Ni이 계면에 있는 Pd/Ni/p-GaN의 경우에는 52$0^{\circ}C$까지의 열처리에 의하여 Ni과 Pd가 골고루 섞이고 그 평탄성도 유지되고 barier height의 변화도 없었다. 더 높은 $650^{\circ}C$ 가열에 의해서는 surface free energy가 작은 Ga의 활발한 편석 현상으로 인해 표면은 Ga이 풍부한 Pd-Ga의 합금층으로 덮이고, 동시에 작은 pinhole들이 발생하며 barrier height도 0.3eV 가량 증가하게 된다. 반면에 증착당시 Pd이 계면에 있는 Ni/Pd/p-GaN의 경우에는 40$0^{\circ}C$의 가열까지는 두 금속이 그들 계면에서부터 섞이나, 52$0^{\circ}C$의 가열에 의해 이미 barrier height가 0.2eV 가량 증가하기 시작하였다. 더 높은 $650^{\circ}C$가열에 의해서는 커다란 pinhole, 0.5eV 가량의 barrier height 증가, Pd clustering이 동시에 관찰되었다. 따라서 Ni과 Pd의 일함수는 물론 thermal expansion coefficient가 거의 같으며 surface free energy도 거의 일치한다는 점을 감안하면, 이렇게 뚜렷한 열적 안정성의 차이는 GaN와 contact metal과의 반응시작 온도(disruption onset temperature)의 차이에 기인함을 알 수 있었다. 즉 계면에서의 반응에 의해 편석되는 Ga에 의해 박막의 strain이 이완되면, pinhole 등의 박막결함이 줄어 들고, 이는 계면의 N의 out-diffusion을 방지하여 p-type GaN의 barrier height 증가를 막게 된다.

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A Study on the Genetic Risk and Carcinogenesis Probability of Prostate Cancer Patients Due to Photoneutron Generation (광중성자 발생으로 인한 전립샘암 환자의 유전적 위험과 발암의 확률에 관한 연구)

  • Joo-Ah Lee
    • Journal of the Korean Society of Radiology
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    • v.17 no.3
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    • pp.473-479
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    • 2023
  • In this study, the dose of photoneutrons generated during radiotherapy of prostate cancer using high energy was measured using a photo-stimulated luminescence dosimeter. In addition, this study was intended to study the probability of side effects occurring in the abdomen. A medical linear accelerator capable of generating 15 MV energy, True Beam STx (Varian Medical Systems, USA) and a radiation treatment planning system (Eclipse, Varian Medical Systems, USA) were used. A human body phantom was installed on the couch of the linear accelerator, and an Albedo Neutron Optical Stimulation Luminescence Neutron Detector (Landauer Inc., IL, USA) was used to measure the photoneutron dose. The photoneutron dose value in the abdomen of VMAT and 3C-CRT was 52.8 mSv, more than twice as high as VMAT compared to 3D-CRT. During radiotherapy of prostate cancer, the probability of causing side effects in the abdomen due to light neutron dose was calculated to be 3.2 per 1,000 for VMAT and 1.4 for 3D-CRT. By studying the abdomen, which has a major side effect that can occur during radiotherapy of prostate cancer, it is expected that it will be used as a meaningful study to study the quality of life and stochastic effect of prostate cancer patients

The Accuracy Evaluation according to Dose Delivery Interruption and Restart for Volumetric Modulated Arc Therapy (용적변조회전 방사선치료에서 선량전달의 중단 및 재시작에 따른 정확성 평가)

  • Lee, Dong Hyung;Bae, Sun Myung;Kwak, Jung Won;Kang, Tae Young;Back, Geum Mun
    • The Journal of Korean Society for Radiation Therapy
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    • v.25 no.1
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    • pp.77-85
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    • 2013
  • Purpose: The accurate movement of gantry rotation, collimator and correct application of dose rate are very important to approach the successful performance of Volumetric Modulated Arc Therapy (VMAT), because it is tightly interlocked with a complex treatment plan. The interruption and restart of dose delivery, however, are able to occur on treatment by various factors of a treatment machine and treatment plan. If unexpected problems of a treat machine or a patient interrupt the VMAT, the movement of treatment machine for delivering the remaining dose will be restarted at the start point. In this investigation, We would like to know the effect of interruptions and restart regarding dose delivery at VMAT. Materials and Methods: Treatment plans of 10 patients who had been treated at our center were used to measure and compare the dose distribution of each VMAT after converting to a form of digital image and communications in Medicine (DICOM) with treatment planning system (Eclipse V 10.0, Varian, USA). We selected the 6 MV photon energy of Trilogy (Varian, USA) and used OmniPro I'mRT system (V 1.7b, IBA dosimetry, Germany) to analyze the data that were acquired through this measurement with two types of interruptions four times for each case. The door interlock and the beam-off were used to stop and then to restart the dose delivery of VMAT. The gamma index in OmniPro I'mRT system and T-test in Microsoft Excel 2007 were used to evaluate the result of this investigation. Results: The deviations of average gamma index in cases with door interlock, beam-off and without interruption on VMAT are 0.141, 0.128 and 0.1. The standard deviations of acquired gamma values are 0.099, 0.091, 0.071 and The maximum gamma value in each case is 0.413, 0.379, 0.286, respectively. This analysis has a 95-percent confidence level and the P-value of T-test is under 0.05. Gamma pass rate (3%, 3 mm) is acceptable in all of measurements. Conclusion: As a result, We could make sure that the interruption of this investgation are not enough to seriously affect dose delivery of VMAT by analyzing the measured data. But this investigation did not reflect all cases about interruptions and errors regarding the movement of a gantry rotation, collimator and patient So, We should continuously maintain a treatment machine and program to deliver the accurate dose when we perform the VMAT for the many kinds of cancer patients.

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Assessment of the Value and Distribution of Geological Heritages in Korea: Jeolla Province (한국의 지질유산 분포와 가치평가: 전라권)

  • Cho, Hyeongseong;Kang, Hee-Cheol;Kim, Jong-Sun;Cheong, Daekyo;Paik, In Sung;Lim, Hyoun Soo;Choi, Taejin;Kim, Hyun Joo;Roh, Yul;Cho, Kyu-Seong;Huh, Min;Shin, Seungwon
    • The Journal of the Petrological Society of Korea
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    • v.28 no.4
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    • pp.319-345
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    • 2019
  • Recently planification and effort for management, assessment and discovery of geological heritagesare being increasingly demanded with institutional strategies such as geopark, as their preservation is asked socially. In this study, we discovered geological heritages in the Jeolla Province and then performed assessment of the value and grading of them and finally suggested a promising and suitable site for the National Geopark. A total of 325 geological heritages are listed on literature review and then detailed description in field and assessment of the value for selected 158 geoheritages are completed. The assessment items are categorized into intrinsic value, subsidiary value, and preservation/management part. The intrinsic value is subdivided into scientific/educational value, composed of representativeness, rarity, geodiversity, typicality, reproducibility, and particularity, and geomorphological/landscape value composed of scale, naturality (integrity), scenery (aesthetic value). Also, subsidiary value consist of 7 subsections of soil function, ecological function, tourism value, geological resource, historical value, folk tale or legend and symbolic value, and accessibility, convenient facility (infrastructure), management condition (legal protection) is evaluated in preservation/management part. The heritages in the Jeolla Province subdivided into three types: 73 geological heritages, 42 geomorphological heritages, and 42 composite heritages. Based on points acquired in intrinsic value, all geological heritages are graded Class-I to -V. As a result, numbers of geoheritage belong to Class-I (protection at world level), -II (protection at national level), -III (nationdesignated management), -IV (involved management list), -V (candidate management list) are 12, 39, 52, 34, 21, respectively. Finally, we construct database based on Arc-GIS with all informations for each geological heritage and suggest three promising and suitable sites, 'Jirisan-Seomjingang Area' and 'south coast area of Jeolla Province', for the National Geopark.

Synthesis of Visible-working Pt-C-TiO2 Photocatalyst for the Degradation of Dye Wastewater (염료폐수 분해를 위한 가시광 감응형 Pt-C-TiO2 광촉매의 합성)

  • Hahn, Mi Sun;Yun, Chang Yeon;Yi, Jongheop
    • Clean Technology
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    • v.11 no.3
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    • pp.123-128
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    • 2005
  • Among various metal oxides semiconductors, $TiO_2$ is the most studied semiconductor for environmental clean-up applications due to its unique ability in photocatalyzing various organic contaminants, its chemical inertness, and nontoxicity. $TiO_2$, however, has a few drawbacks to be solved such as reactivity mainly working under ultraviolet irradiation (${\lambda}$ < 387 nm) and electron - hole recombination on $TiO_2$. In this study, to extend the absorption range of $TiO_2$ into the visible range and enhance electron - hole separation, we synthesized platinum (Pt) deposited $C-TiO_2$. The presence of Pt as an electron sink has been known to snhance the separation of photogenerated electron-hole pairs and induce the thermal decomposition. The characterization of as-synthesized $Pt-C-TiO_2$ was performed by Transmission Electron Microscopic (TEM), the Brunuer-Emmett-Teller (BET) method, X-ray Diffractometer (XRD), UV-vis spectrometer (UV-DRS), and X-ray Photoelectron Spectroscopy (XPS). In order to estimate the photocatalytic activity of the synthesized materials, the photoelectron Spectroscopy (XPS). In order to estimate the photocatalytic activity of the synthesized materials, the photodegradation experiment of an azo dye (Acid Red 44; $C_{10}H_7N=NC_{10}H_3(SO_3Na)_2OH$)was carried out by using an Xe arc lamp (300 W, Oriel). A 420 nm cut-off filter was used for visible light irradiation. From the results, Pt-deposited $C-TiO_2$ showed a far superior phothdegradation activity to Degussa P25, the commercial product under the irradiation of visible light and enhanced photocatalytic activity of visible-working $C-TiO_2$. This is a useful result into the application for the purification system of dye wastewater using visible energy of sun light.

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A Bibliographic Study on the Types of Differential Diagnosis of Amnesia (건망(健忘)의 변증분형(辨證分型)에 대(對)한 연구(硏究))

  • Choi, Yong-Jun;Seong, Gang-Gyoung;Mun, Byoung-Sun
    • The Journal of Korean Medicine
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    • v.17 no.1 s.31
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    • pp.374-406
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    • 1996
  • This study has been carried out to investigate the types of differential diagnosis of amnesia. The results are as follows; 1. Amnesia has various types of differential diagnosis(辨證分型) ; deficiency of both the heart and spleen(心脾兩虛型), deficiency of the heart(心虛型), deficiency of the kidney(腎虛型), breakdown of the coordination between the heart and the kidney(心腎不交型), mental confusion due to phlegm(痰迷心竅型), accumulation of stagnant blood(蓄血型), internal injury by seven emotion (七情所傷型). 2. The type of deficiency of both the heart and spleen(心脾兩虛型) occurs when the heart and spleen is injured by overthinking(思慮過度), The symptoms are heart palpitation(心悸), continuous palpitation(??), insomnia(少寐), hypochondric discomfort(心煩), dream disturbed sleep(多夢), being easy to be scared(易驚), dizziness(眩暈), these are caused by blood deficiency of the heart(心血不足), poor appetite(飮食不振), loss of appetite(納?), short breath(氣短), sense of turgid abdormen(腹部膨滿感), loose stool(泥狀便), these are caused by deficiency of the spleen(脾虛), lassitude and weakness (身倦乏力), lassitude of the extremities (四肢無力), dim complexion (面色少華), pale lips(舌質淡), thready and feeble(脈細弱無力), these are caused by deficiency of both qi and the blood(氣血虛損). The remedy is nourishing the heart-blood(養心血) and regulating the spleen(理脾土). I can prescribe the recipes such as Guibitang(歸脾湯), Gagambosimtang(加減補心湯), Seongbitang(醒脾湯), Insin-guisadan(引神歸舍丹), Insamyangyoungtang(人蔘養榮湯), Sojungjihwan(小定志丸), Yungjigo(寧志膏), Palmijungjihwan(八味定志丸), etc., 3. The type of deficiency of the heart(心虛型) occurs when the heart-blood is injured by the mental tiredness(神勞) and so blood cannot nourish the heart. The symptoms are amnesia(健忘), short breath(氣短), heart palpitation(心悸), perspire spontaneously(自汗), facial pallidness(顔面蒼白), pale lips (舌質淡白), feeble pulse and lassitude(脈虛無力), intermittent pulse(結代脈). The remedy is nourishing the hart and blood and allaying restlessness(補心益血安神). I can prescribe the recipes such as Chenwangbosimdan(天王補心丹), Jeongji-hwan(定志丸), Gaesimhwan(開心丸), Youngjigo(寧志膏), Chilseonghwan(七聖丸), Baegseogyoungtang(白石英湯), Oseohwan(烏犀丸), Yangsinhwan(養神丸), Guisindan(歸神丹), Bogsinsan(茯神散), Jinsamyohyangsan(辰砂妙香散), Cheongeumboksinsan(千金茯神散), Samjotang(蔘棗湯), jangwonhwan(壯元丸), Sa gunjatang(四君子湯) minus rhizoma atractylodis macrocephalae(白朮) plus rhizoma acori graminei(石菖蒲), radix polygalae(遠志), cinnabaris(朱砂), etc. 4. The type of deficiency of the kidney(腎虛型) occurs when the kidney-qi and kidney-essence is deficient(腎氣腎精不足) and so it cannot nourish the brain. The symptoms arc amnesia(健忘), ache at the waist and lassitude in the lower extremities(腰산腿軟), dizziness and tinnitus(頭暈耳嗚), emmission and premature ejaculation(遺精早泄), burning sensation of the five centres(五心煩熱), flushed tongue(舌紅), rapid and small palse(脈細數). The remedy is nourishing the kidney and strengthen the essence(補腎益精). I can prescribe the recipes such as Gagamgobonhwan(加減固本丸), Jeongjihwan(定志丸), Gongseongchlmjungdan(孔聖枕中丹), Yugmigihwanghwan(六味地黃丸) plus ra-dix polygalae(遠志), fructus schizandrae(五味子), Yugmigihwanghwan(六味地黃丸) plus radix polygalae(遠志), fructus schizandrae(五味子), rhizoma acori graminei(石菖蒲), semen zizyphi spinosae(酸棗仁), Palmihwan(八味丸) plus fructus schizandrae(五味子), semen zizyphi spinosae(酸棗仁). etc., 5. The type of breakdown of the coordination between the heart and the kidney (心腎不交型) occurs when the heart-fire(心火) and kidney-fluid(腎水) are imbalanced. The symptoms are amnesia(健忘), hypochondric discomfort(心煩), insomnia(失眠), dizziness and tinnitus(頭最耳嗚), feverish sensation m the palms and soles(手足心熱), emmision(遺精), ache at the waist and lassitude in the lower extremities(腰?腿軟), flushed tongue(舌紅), rapid pulse(脈數). The remedy is coordinating each other(交通心腎). I can prescribe the recipes such as Gangsimdan(降心丹), Jujaghwan(朱雀丸), Singyotang(神交湯), Simsinyang- gyotang(心腎兩交湯), Yugmihwan(六味丸) plus fructus schizandrae(五味子), radix polygalae(遠志), Yugmihwan(六味丸) plus fructus schizandrae(五味子), radix polygalae(遠志), rhizoma acari graminei(石菖蒲), semen zizyphi spinosae(酸棗仁), etc., 6. The type of mental confusion due to phlegm(痰迷心竅型) occurs when the depressed vital energy(氣鬱) create phlegm retention(痰飮) and phlegm stagnancy(痰濁) put the heart and sprit(心神) out of order. The symptoms arc amnesia(健忘), dizziness(頭暈), chest distress(胸悶), nausea(惡心), dull(神思欠敏), dull and slow facial expression(表情遲鈍), tongue with yellow and greasy fur(舌苔黃?), sliperry pulse(脈滑). The remedy is removing heat from the heart to restore consciousness and dispersing phlegm(淸心化痰開竅) I can prescribe the recipes such as Gamibogryeongtang(加味茯?湯), Goa-rujisiltang(瓜蔞枳實湯), Jusaansinhwan(朱砂安神丸), Dodamtang(導痰湯) plus radix saussurea(木香), Yijintang(二陳湯) plus succus phyllostachyos(竹瀝), rhizoma zingiberis(生薑) Ondamtang(溫膽湯) plus rhizoma acori graminei(石菖蒲), rhizoma curcumae aromaticae(鬱金), etc., 7. The type of accumulation of stagnant blood(蓄血型) occurs when the blood is accumulated in the lower part of body. The symptoms are amnesia(健忘), chest distress(胸悶), icteric skin(身黃), rinsing the mouth but don't wanting eat(漱水不欲燕), madness(發狂), black stool(屎黑), pain in the lower abdomen(小腹硬痛). The remedy is dispersing phlegm and absorb clots (化痰化瘀), I can prescribe the recipes such as Jeodangtang(抵當湯), Daejeodanghwan(代抵當丸), Hyeolbuchugeotang (血府逐瘀湯) plus rhizoma acori graminei (石菖蒲), rhizoma curcumae aromaticae(鬱金), Jusaansinhwan(朱砂安神丸) plus rhizoma curcumae aromaticae(鬱金), radix polygalae(遠志), semen persicae(桃仁), cortex moutan radicis(收丹皮), etc., 8. The type of internal injury by seven emotion(七情所傷型) occurs when the anger injures the will stored in the kidney(腎志). The symptoms are amnesia(健忘), heart palpitation(心悸). hot temper(易怒), being easy to be scared(善驚), panic(易恐). The remedy is relieving the depressed liver and regulating the circulation of qi(疏肝解鬱). I can prescribe the recipes such as Tongultang(通鬱湯), Sihosogantang(柴胡疏肝湯) plus rhizoma acari graminei(石菖蒲), rhizoma curcumae aromaticae(鬱金), etc.

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Comparison of the degree of conversion of light-cured resin cement in regard to porcelain laminate thickness, light source and curing time using FT-IR (도재 라미네이트 두께와 광원 및 광조사 시간에 따른 광중합형 레진 시멘트의 FT-IR을 이용한 중합도 비교)

  • Yuh, Chi-Sung;Kim, Jee-Hwan;Kim, Sun-Jai;Lee, Yong-Keun;Shim, June-Sung
    • The Journal of Korean Academy of Prosthodontics
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    • v.47 no.4
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    • pp.416-423
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    • 2009
  • Statement of problem: The degree of light attenuation at the time of cementation of the PLV restoration depends on characteristics such as thickness, opacity and shade of the restorations, which interfere with light transmittance and, as a result, may decrease the total energy reaching the luting cement. Purpose: The purpose of this study was to compare the degree of conversion of light-cured resin cements measuring by FT-IR in regard to different thickness, light devices and curing time. Material and methods: In the control group, a clear slide glass (1.0 mm) was positioned between the light cured resin cement and light source. The specimens of ceramics were made with IPS Empress Esthetic. The ceramics were fabricated with varying thicknesses-0.5, 1.0, 1.5 mm with shade ETC1. Rely $X^{TM}$ Veneer with shade A3, light-cured resin cement, was used. Light-activation was conducted through the ceramic using a quartz tungsten halogen curing unit, a light emitting diode curing unit and a plasma arc curing unit. The degree of conversion of the light-cured resin cement was evaluated using FT-IR and OMNIC. One-way ANOVA and Tukey HSD test were used for statistical analysis ($\alpha$< .05). Results: The degree of conversion (DC) of photopolymerization using QTH and LED was higher than results of using PAC in the control group. After polymerization using QTH and LED, the DC results from the different ceramic thickness- 0.5 mm, 1.0 mm, 1.5 mm- did not show a significant difference when compared with those of control group. However, the DC for polymerization using PAC in the 1.5mm ceramic group showed significantly lower DC than those of the control group and 0.5 mm ceramic group (P<.05). At 80s and 160s, the DC of light-cured resin cement beneath 1.0 mm ceramic using LED was significantly higher than at 20s (P<.05). Conclusion: Within the limitation of this study, when adhering PLV to porcelain with a thickness between 0.5-1.5 mm, the use of PAC curing units were not considered however, light cured resin cements were effective when cured for over 40 seconds with QTH or LED curing units. Also, when curing the light cured resin cements with LED, the degree of polymerization was not proportional with the curing time. Curing exceeding a certain curing time, did not significantly affect the degree of polymerization.

Study on Hydrogen Production and CO Oxidation Reaction using Plasma Reforming System with PEMFC (고분자 전해질 연료전지용 플라즈마 개질 시스템에서 수소 생산 및 CO 산화반응에 관한 연구)

  • Hong, Suck Joo;Lim, Mun Sup;Chun, Young Nam
    • Korean Chemical Engineering Research
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    • v.45 no.6
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    • pp.656-662
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    • 2007
  • Fuel reformer using plasma and shift reactor for CO oxidation were designed and manufactured as $H_2$ supply device to operate a polymer electrolyte membrane fuel cell (PEMFC). $H_2$ selectivity was increased by non-thermal plasma reformer using GlidArc discharge with Ni catalyst simultaneously. Shift reactor was consisted of steam generator, low temperature shifter, high temperature shifter and preferential oxidation reactor. Parametric screening studies of fuel reformer were conducted, in which there were the variations of the catalyst temperature, gas component ratio, total gas ratio and input power. and parametric screening studies of shift reactor were conducted, in which there were the variations of the air flow rate, stema flow rate and temperature. When the $O_2/C$ ratio was 0.64, total gas flow rate was 14.2 l/min, catalytic reactor temperature was $672^{\circ}C$ and input power 1.1 kJ/L, the production of $H_2$ was maximized 41.1%. And $CH_4$ conversion rate, $H_2$ yield and reformer energy density were 88.7%, 54% and 35.2% respectively. When the $O_2/C$ ratio was 0.3 in the PrOx reactor, steam flow ratio was 2.8 in the HTS, and temperature were 475, 314, 260, $235^{\circ}C$ in the HTS, LTS, PrOx, the conversion of CO was optimized conditions of shift reactor using simulated reformate gas. Preheat time of the reactor using plasma was 30 min, component of reformed gas from shift reactor were $H_2$ 38%, CO<10 ppm, $N_2$ 36%, $CO_2$ 21% and $CH_4$ 4%.