• Title/Summary/Keyword: One-phase reaction

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Product Phase Control During Interdiffusion Reactions (상호 확산 반응 중의 생성상 제어)

  • Park, Joon-Sik;Kim, Ji-Hoon;Perepezko, John R.
    • Journal of Korea Foundry Society
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    • v.26 no.1
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    • pp.27-33
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    • 2006
  • Phase evolutions involving nucleation stages together with diffusional growth have been examined in order to provide a guideline for determining rate limiting stages during phase evolutions. In multiphase materials systems in coatings, composites or multilayered structures, diffusion treatments often result in the development of metastable/intermediate phases at the reaction interfaces. The development of metastable phases during solid state interdiffusion demonstrates that the nucleation reaction can be one controlling factor. Also, the concentration gradient and the relative magnitudes of the component diffusivities provide a basis for a phase selection and the application of a kinetic bias strategy in the phase selection. For multicomponent alloy systems, the identification of the operative diffusion pathway is central to control phase formation. Experimental access to the nucleation and growth stage is discussed in thin film multi layers and bulk samples.

Thermal Behavior of Dickite (딕카이트의 열적 특성 연구)

  • 조현구
    • Journal of the Mineralogical Society of Korea
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    • v.12 no.1
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    • pp.11-22
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    • 1999
  • Thermal behavior of dickite was studied by thermal analysis, X-ray diffraction analysis, electron microprobe analysis, and scanning electron microscopy, Dickite has an endothermic peak at about$ 650^{\circ}C$ and an exothermic one at $960^{\circ}C$ in the differential thermal analysis. The endothermic reaction is assigned to the decomposition of dickite to meta-dickite. Hydroxyl radicals are removed from dickite structure by the reaction, resulting in the weight loss about 10.5~14.5% and appearance of a 14$\AA$ phase different from other kaolin minerals. The reaction slowly proceed in the range of $200^{\circ}C$. As the completion of decomposition, aciclular mullite forms at the expense of meta-dickite plates with random crystallographic relationship. Mullites have diverse silica versus alumina ratio. The exothermic reaction without weight loss seems to be due to the formation of spinel and amorphous silica. The spinel phase shows cryptocrystalline globular morphology accompanying a little amount of silica. From spinel phase shows cryptocrystalling globular morphology accompanying a little amount of silica. From this work, it is suggested that mullite is formed from meta-dickite much lower temperature than the reported one in the previous works.

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MPS eutectic reaction model development for severe accident phenomenon simulation

  • Zhu, Yingzi;Xiong, Jinbiao;Yang, Yanhua
    • Nuclear Engineering and Technology
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    • v.53 no.3
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    • pp.833-841
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    • 2021
  • During the postulated severe accident of nuclear reactor, eutectic reaction leads to low-temperature melting of fuel cladding and early failure of core structure. In order to model eutectic melting with the moving particle semi-implicit (MPS) method, the eutectic reaction model is developed to simulate the eutectic reaction phenomenon. The coupling of mass diffusion and phase diagram is applied to calculate the eutectic reaction with the uniform temperature. A heat transfer formula is proposed based on the phase diagram to handle the heat release or absorption during the process of eutectic reaction, and it can combine with mass diffusion and phase diagram to describe the eutectic reaction with temperature variation. The heat transfer formula is verified by the one-dimensional melting simulations and the predicted interface position agrees well with the theoretical solution. In order to verify the eutectic reaction models, the eutectic reaction of uranium and iron in two semi-infinite domains is simulated, and the profile of solid thickness decrease over time follows the parabolic law. The modified MPS method is applied to calculate Transient Reactor Test Facility (TREAT) experiment, the penetration rate in the simulations are agreeable with the experiment results. In addition, a hypothetical case based on the TREAT experiment is also conducted to validate the eutectic reaction with temperature variation, the results present continuity with the simulations of TREAT experiment. Thus the improved method is proved to be capable of simulating the eutectic reaction in the severe accident.

A Study of Ground Reaction Forces During Professional Golfer's Swing with Different Golf Clubs (클럽별 골프 스윙 시 지면 반력 변화에 관한 연구)

  • Hur, You-Jein;Moon, Gun-Pil;Lim, Jung
    • Korean Journal of Applied Biomechanics
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    • v.15 no.2
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    • pp.103-111
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    • 2005
  • The purpose of this study was to analysis golf swing in accordance with each club using ground reaction force data. The subject of this study was current professional golf players in Korea. Golf clubs used for this study were driver, iron4, iron7, and pitching. The ground reaction force for left and right foot was collected by one Kistler and one Bertec force platforms. Also collected visual data by NC high speed camera to check the phase which was composed of address, top of backswing, impact and finish. Sampling rate was 600Hz both ground reaction forces data and visual data. The conclusion are as follows. 1. An aspect of change for ground reaction force was that the weight between the left foot and right foot were contrary to each other in general as the phase. 2. Without regard to the type of golf club, the ratio of necessary ground reaction forces for each phase in accordance with address, top of backswing, impact, and finish was comparatively identical. 3. According to the type of golf club, the tendency of Fy was not varied. In terms of Driver, at the moment of impact, the weight of foot-both right and left-was moved to the movement direction of golf because of the rotation force from swing.

Grief Stages and Responses of Bereaved Mother Who Lost Her Children with Cancer (암으로 자녀와 사별한 어머니의 슬픔단계와 반응)

  • 이원희;황애란
    • Journal of Korean Academy of Nursing
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    • v.33 no.6
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    • pp.847-855
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    • 2003
  • Purpose: This study was done to develop a bereaved family care program by identifying characteristics of a grief healing process in a child loss. Method: The subjects were five bereaved mothers who have lost their children with cancer. Data was collected with in-depth interviews using grief phase assessment tool and grief reaction assessment tool from 1, February, 2001 to 31 August, 2002. Data was analyzed on the basis of two tools. Result: Process of grief in general was as follows: evading phase was within one week - one month, confrontation phase was 5 - 12 months, and reconciliation phase was after 9 months and still going on when the study was finished. Grief reaction in five (physical, cognitive, emotional, social, and spiritual) dimensions was stabilized when the phase moved into reconciliation phase. Influencing factors were intimacy and expectation towards child, social support, personality, prior loss experience, coping style, religion, culture, family cohesion, openness of communication, and stress events. Conclusion: These results suggest that a bereaved family care program considering characteristics of Korean culture should be developed and activated.

Efficient Macrocyclization for Cyclicpeptide Using Solid-Phase Reaction

  • Kim, Joong-Hup;Hong, Il-Khee;Kim, Hyo-Jeong;Jeong, Hyeh-Jean;Choi, Moon-Jeong;Yoon, Chang-No;Jeong, Jin-Hyun
    • Archives of Pharmacal Research
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    • v.25 no.6
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    • pp.801-806
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    • 2002
  • Cyclicpeptides are important targets in peptide synthesis because of their interesting biological properties. Constraining highly flexible linear peptides by cyclization is one of the mostly widely used approaches to define the bioactive conformation of peptides. Cyclic peptides often have increased receptor affinity and metabolic stability over their linear counterparts. We carried out virtual screening experiment via docking in order to understand the interaction between HLE-Human Leukocyte Elastase and ligand peptide and to identify the sequence that can be a target in various ligand peptides. We made cyclic peptides as a target base on Metlle-Phe sequence having affinity for ligand and receptor active site docking. There are three ways to cyclize certain sequences of amino acids such as Met-lie-Phe-Gly-Ile. First is head-to-tail cyclization method, linking between N-terminal and C-terminal. Second method utilizes amino acid side chain such as thiol functional group in Cys, making a thioether bond. The last one includes an application of resin-substituted amino acids in solid phase reaction. Among the three methods, solid phase reaction showed the greatest yield. Macrocyclization of Fmoc-Met-Ile-Phe-Gly-Ile-OBn after cleavage of Fmoc protection in solution phase was carried out to give macrocyclic compound 5 in about 7% yield. In the contrast with solution phase reaction, solid phase reaction for macrocyclization of Met-Ile-Phe-Gly-Ile-Asp-Tentagel in normal concentrated condition gave macrocyclic compound 7 in more than 35% yield.

Fabrication of Silicon Nitride Ceramics by Gel-Casting and Microwave Gas Phase Reaction Sintering(II) : Microwave Nitridation of Silicon and Microwave Sintering of Silicon Nitride (Gel-Casting 및 마이크로파 기상반응소결에 의한 질화규소 세라믹 제조에 대한 연구(II) : 마이크로파에 의한 실리콘의 질화반응 및 질화규소의 소결)

  • Bai, Kang;Woo, Sang-Kuk;Han, In-Sub;Seo, Doo-Won
    • Journal of the Korean Ceramic Society
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    • v.48 no.5
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    • pp.354-359
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    • 2011
  • Silicon nitride ceramics were prepared by microwave gas phase reaction sintering. By this method higher density specimens were obtained for short time and at low temperature, compared than ones by conventional pressureless sintering, even though sintering behaviors showed same trend, the relative density of sintered body inverse-exponentially increases with sintering temperature and/or holding time. And grain size of ${\beta}$-phase of the microwave sintered body is bigger than one of the conventional pressureless sintered one. Also they showed good bending strengths and thermal shock resistances.

Psychosocial Reaction Patterns to Alopecia in Female Patients with Gynecological Cancer undergoing Chemotherapy

  • Ishida, Kazuko;Ishida, Junko;Kiyoko, Kanda
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.3
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    • pp.1225-1233
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    • 2015
  • This study aims to clarify the psychosocial reactions of female patients with gynecological cancer undergoing chemotherapy and in the process of suffering from alopecia and to examine their nursing support. The target group comprised female patients who had received two or more cycles of chemotherapy, were suffering from alopecia, and were aged 30-65. Data were collected from semi-structured interviews, conducted from the time the patients were informed by their doctors that they might experience alopecia due to chemotherapy to the time they actually experienced alopecia and until they were able to accept the change. Inductive qualitative analysis was employed to close in on the subjective experiences of the cancer patients. The results showed the existence of six phases in the psychosocial reactions in the process of alopecia: phase one was the reaction after the doctor's explanation; phase two was the reaction when the hair starts to fall out; phase three was the reaction when the hair starts to intensely fall out; phase four was the reaction when the hair has completely fallen out; phase five was the reaction to behavior for coping with alopecia; and phase six was the reaction to change in interpersonal human relationships. The results also made it clear that there are five types of reaction patterns as follows: 1) treatment priority interpersonal relationship maintenance type; 2) alopecia agitated interpersonal relationship maintenance type; 3) alopecia agitated interpersonal relationship reduction type; 4) alopecia denial interpersonal relationship reduction type; and 5) alopecia denial treatment interruption type. It is important to find out which of the five types the patients belong to early during treatment and provide support so that nursing intervention that suits each individual can be practiced. The purpose of this study is to make clear the process in which patients receiving chemotherapy come to accept alopecia and to examine evidence-based nursing care on patients with strong mental distress from alopecia.

Phase Separation Characteristics via Bunsen Reaction in Sulfur-Iodine Thermochemical Hydrogen Production Process (SI 열화학 수소 제조 공정에서 분젠 반응을 통한 상 분리 특성)

  • Lee, Kwang-Jin;Kim, Young-Ho;Park, Chu-Sik;Bae, Ki-Kwang
    • Journal of Hydrogen and New Energy
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    • v.19 no.5
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    • pp.386-393
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    • 2008
  • The Sulfur-iodine(SI) thermochemical cycle is one of the most promising methods for massive hydrogen production. For the purpose of continuous operation of SI cycle, phase separation characteristics into two liquid phases ($H_2SO_4$-rich phase and $HI_x$-rich phase) were directly investigated via Bunsen reaction. The experiments for Bunsen reaction were carried out in the temperature range, from 298 to 333 K, and in the $I_2/H_2O$ molar ratio of $0.109{\sim}0.297$ under a continuous flow of $SO_2$ gas. As the results, solubility of $SO_2$, decreased with increasing the temperature, had considerable influence on the global composition in the Bunsen reaction system. The amounts of impurity in each phase(HI and $I_2$ in $H_2SO_4$-rich phase and $H_2SO_4$ in $HI_x$-rich phase) were decreased with increasing $H_2SO_4$ molar ratio and temperature. To control the amounts of impurity in $HI_x$-rich phase, temperature is a factor more important than $I_2/H2_O$ molar ratio. On the other hand, the affinity between $HI_x$ and $H_2O$ was increased with increasing $I_2/H2_O$molar ratio.

The Comparison of Bunsen Reaction With Phase Separation in Sulfur-lodine Thermochemical Hydrogen Production Process (황-요오드 열화학 수소 제조 공정에서 분젠 반응과 상 분리 비고)

  • Lee, Kwang-Jin;Ahn, Sueng-Hyuk;Kim, Young-Ho;Park, Chu-Sik;Bae, Ki-Kwang
    • Journal of Hydrogen and New Energy
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    • v.19 no.2
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    • pp.111-117
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    • 2008
  • A Bunsen reaction section is a primary stage of Sulfur-iodine thermochemical hydrogen production cycle. This section is important, because it decides the efficiency of next stages. In order to produce hydrogen very efficiently, the characteristics of Bunsen reaction were investigated via two experimental methods. The one is a phase separation of $H_2SO_4-HI-H_2O-I_2$ mixture system, and the other is a direct Bunsen reaction. The characteristics of each method were investigated and compared. As the result of this study, the amount of HI and $I_2$ in $H_2SO_4$ phase via Bunsen reaction was more decreased than that via $H_2SO_4-HI-H_2O-I_2$ mixture system with increasing $I_2$ concentration. However, the amount of $H_2SO_4$ in $HI_x$ phase via Bunsen reaction was remarkably increased with increasing $I_2$ concentration, while that via $H_2SO_4-HI-H_2O-I_2$ mixture system was decreased. On the other hand, the range of initial composition which is able to separate into two liquid phases without $I_2$ solidification was almost alike.