• Title/Summary/Keyword: Holding Time

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Preparation of β-FeSi2 Thermoelectric Materials by MA/SPS Process -Formation ofβ-FeSi2Phase- (MA/SPS 공정에 의한 β-FeSi2 열전재료의 제조(I) -β-FeSi2상의 형성-)

  • Kim, Hwan-Tae;Gwon, Yeong-Sun;Lee, Chung-Hyo
    • Korean Journal of Materials Research
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    • v.12 no.3
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    • pp.176-181
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    • 2002
  • Fabrication of ${\beta}-FeSi_2$ was attempted by making use of the combined process of mechanical alloying (MA) and spark plasma sintering (SPS). MA was performed under the Ar gas atmosphere using mixed powders of pure iron and silicon having the mole fraction of 1:2. SPS process was performed at 800-85$0^{\circ}C$ with the applied pressure of 50MPa and the holding time was ranging from 0 to 30min. The mechanically alloyed powder by cyclic operation of rotor for 15hrs consisted of $\varepsilon$-FeSi and Si phases. When this mechanically alloyed powder was sintered by SPS process above 85$0^{\circ}C$, $\varepsilon$-FeSi and ${\alpha}-Fe_2Si_5$ phase were formed. Bulk product sintered at 82$0^{\circ}C$ for 30min consisted of ${beta}-FeSi_2$ phase with a small fraction of $\varepsilon$-FeSi and the density of sintered specimen was 75.3% theoretical density. It was considered that the MA/SPS combined process was effective for the preparation of ${\beta}-FeSi_2$ without heat treatment process after sintering.

Characteristics of Nano-Sized, α-2ZrO2·P2O5 Powder Prepared by Polyvinyl Alcohol Solution Method (Polyvinyl Alcohol 용액법에 의해 제조된 나노크기 α-2ZrO2·P2O5 분말의 특성 연구)

  • Ma, Chung-Il;Lee, Sang-Jin
    • Korean Journal of Materials Research
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    • v.27 no.4
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    • pp.179-183
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    • 2017
  • $2ZrO_2{\cdot}P_2O_5$ powder, which is not synthesized by solid reaction method, was successfully synthesized through PVA solution method. In this process, the firing temperature and the PVA content strongly affected the crystallization behavior and final particle size. A stable ${\alpha}$-phase $2ZrO_2{\cdot}P_2O_5$ was synthesized at a firing temperature of $1200^{\circ}C$ and holding time of 4 h. ${\beta}$-phase $2ZrO_2{\cdot}P_2O_5$ was observed, with un-reacted $ZrO_2$ phases, for firing temperatures lower than $1200^{\circ}C$. In terms of the PVA content effect, the powder prepared with a PVA mixing ratio of 12:1 showed stable ${\alpha}$-phase $2ZrO_2{\cdot}P_2O_5$; however, the ${\beta}$-phase was found to co-exist at relatively higher PVA content. The synthesized ${\alpha}$-phase $2ZrO_2{\cdot}P_2O_5$ powder showed an average particle size of 100~250 nm and an average thermal expansion coefficient of $-2.5{\times}10^{-6}/^{\circ}C$ in the range of room temp. ${\sim}800^{\circ}C$.

A Study on Synthesis of Starch-acryl Pressure Sensitive Adhesive by Soap-free Emulsion Polymerization (무유화제 유화중합에 의한 전분-아크릴 점착제의 합성에 관한 연구)

  • Song, Su-Hyun;Kim, Young-Seok;Cho, Ur-Ryong
    • Elastomers and Composites
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    • v.44 no.4
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    • pp.429-435
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    • 2009
  • The pressure sensitive adhesives (PSA) were synthesized by soap-free emulsion polymerization of acrylic monomers such as butyl acrylate, 2-ethyl hexyl acrylate, and acrylic acid in the presence of starch as a protective colloid and copolymer. The peel strength and holding power of PSA were increased with starch contents due to the enhancement of gel content, But the initial tackiness of PSA was decreased with starch contents. The contact angle analysis of PSA indicated that the wettability was increased with starch contents owing to the increase of polarity by hydroxy group in starch. In the pH measurement of emulsion with time for biodegradability, the starch in the PSA accelerated the lowering of pH due to the formation of organic acids followed by decomposition of starch.

Characteristics and development of Rice Noodle Added with Isolate Soybean Protein (분리대두단백질을 첨가한 쌀국수의 제면특성 및 개발)

  • Park Hee-Kyung;Lee Hyo-Gee
    • Korean journal of food and cookery science
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    • v.21 no.3 s.87
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    • pp.326-338
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    • 2005
  • The purpose of this study was to investigate the effect of isolate soybean protein (ISP) and rice flour on the characteristics of rice noodles. As the levels of ISP and rice flour increased, water binding capacity, swelling power of rice noodle increased. In RVA, pasting temperature, Set back showed an increasing tendency with peak viscosity, holding viscosity, break down, final viscosity of rice noodle increased as the level of rice flour by decreasing. Peak time was not significant. The weight, water absorption and volume of the cooked noodles were decreased. The turbidity of rice noodle increased. The Hunter color L, a-values of the dried rice noodle decreased. Cooked rice noodle quality increased with by decreasing the level of rice flour level. B-values of dried rice noodle and cooked rice noodle increased. Texture profile analysis of cooked rice noodle showed an increase of hardness. Adhesiveness, cohesiveness of cooked rice noodles decreased with by decreasing the level of ISP and rice flour. Gumminess, springiness, chewiness were increased. Sensory evaluation, showed gloss was increased. Hardness and chewiness of the cooked ice noodles were increased. Adhesiveness was not significant. Color and overall- acceptability were increased. Relationship between sensory and mechanical examinations (The overall quality of sensory examination for gloss) had a negative correlation with the mechanical examination for b-value (p.0.05). Mechanical examination for b-value had a positive correlation of sensory evaluation for hardness, chewiness, which had negative correlation of sensory evaluation for color. Scanning Electron, Microscopes observation of rice noodle was showed that the size of the hole grown was increased with by increasing the level of rice flour. From the above results, the most advisable mixture ratio of rice noodle evaluation was can be derived as follows: 171g rice flour, 114g wheat flour, 15g soybean protein isolate, 120ml water, and 6g salt.

Quality Characteristics of Sulgidduk Prepared with Houttuynia cordata Thunb. Powder (어성초 분말을 첨가한 설기떡의 품질 특성)

  • Eun, Soon-Duk;Kim, Mun-Yong;Chun, Soon-Sil
    • Korean journal of food and cookery science
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    • v.24 no.1
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    • pp.23-30
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    • 2008
  • Sulgidduk samples made with additions of 2, 4, 6, 8, and 10% Houttuynia cordata Thunb. powder, and a control were examined for quality characteristics such as moisture content, water activity, color, gelatinization properties, textural characteristics, and sensory qualities in order to determine the optimal ratio of Houttuynia cordata Thunb. powder in the formulation. The moisture contents among the samples ranged from 41.98% to 44.97%, and increased as the content of Houttuynia cordata Thunb. powder increased. The water activities of the samples were not significantly different. As the Houttuynia cordata Thunb. powder content increased, the redness and yellowness of the samples also increased, but lightness decreased. For the gelatinization properties, the additions of Houttuynia cordata Thunb. powder caused decreases in peak viscosity (P) and holding strength viscosity (H). Furthermore, final viscosity (F), setback, and time to peak viscosity decreased with increasing Houttuynia cordata Thunb. powder content; however, breakdown and temperature to peak viscosity were not significantly different among the samples. Hardness and gumminess decreased with increasing Houttuynia cordata Thunb. powder content, and adhesiveness, cohesiveness, chewiness, and resilience also tended to decrease; however, springiness was not significantly different among the samples. In the consumer acceptance test, as the content of Houttuynia cordata Thunb. powder increased, the scores of all evaluated characteristics decreased; while the characteristic intensity ratings showed the reverse effect, and the 2 and 4% Houttuynia cordata Thunb. powder samples obtained fairly good scores. In conclusion, the results indicate that adding $2{\sim}4%$ Houttuynia cordata Thunb. powder to Sulgidduk is optimal, providing good physiological properties and reasonably high overall consumer acceptability.

Effect of Fabrication Processes on the Mechanical Properties of 0.14C-6.5Mn TRIP Steels (0.14C-6.5Mn TRIP강의 기계적 성질에 미치는 제조공정의 영향)

  • Lee, O-Yeon;Ryu, Seong-Il
    • Korean Journal of Materials Research
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    • v.11 no.5
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    • pp.431-437
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    • 2001
  • This research was examined the effect of intercritical heat treatment on the mechanical Properties and retained austenite formation in 0.1C-6.5Mn steels for the development of a high strength high ductility steel. using of transformation induced plasticity due to retained austenite. The stability of retained austenite is very important for the good ductility and it depend on diffusion of carbon and manganese during reverse transformation. It is effective to heat treat at$ 645^{\circ}C$ in order to obtain over 30 vol.% of retained austenite. However, it is more desirable to heat treat at $620^{\circ}C$, considering the volume fraction and mechanical stability of retained austenite. The strength-elongation combination in cold rolled steel sheets after reverse transformed at $620^{\circ}C$ for 1hr was about 4000k9/mm7, but it decreased rapidly with increasing holding time at high temperature due to the decrease of ductility. The addition of 1.1%Si in 0.14C-6.5Mn TRIP steel does not improve the mechanical properties and retained austenite formation.

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Characteristics of Flame Hardening Process for 12Cr Steels (12Cr 강의 이동 화염경화 공정 특성)

  • Kim Gwang-Ho;Lee Min-Ku;Kim Kyeong-Ho;Kim Whung-Whoe;Rhee Chang-Kyu;Kim Gil-Mu
    • Journal of the Korean institute of surface engineering
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    • v.39 no.2
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    • pp.49-56
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    • 2006
  • In this study, the movable flame hardening process of 12Cr steel for a uniform hardness and desirable residual stress have been investigated. For this, the temperature cycles have been controlled accurately as a function of the three processing variables, the flame intensity $I_f$, the scanning velocity $V_s$, and the initial flame holding time $t_h$, where the standard surface temperature $T_{s,\;max}$, was maintained at $960^{\circ}C$. The optimized conditions were $V_s=0.68mn/s\;and\;t_h=67sec$ for the $C_3H_8:O_2\;=\;5:20l/min,\;V_s=0.80mm/s$ and $t_h=56sec$ for the $C_3H_8:O_2=6:24l/min,\;V_s=1.01mm/s\;and\;t_h=48sec$ for the $C_3H_8:O_2=7:28l/min,\;and\;V_s=1.15mm/s$ and $t_h=39sec$ for the $C_3H_8:O_2$=8:32 l/min. The optimally flame-hardened surface exhibited uniform distributions of the hardness and residual compressive stress over the treated area with moderate levels of $470{\sim}490HV_{0.2}$in hardness and $-300{\sim}-450MPa$ in residual stress, which were acceptable on the basis of the acceptance criteria of Siemens AG-KWU and GE Power Generation Engineering.

Android Remote Monitoring System of Ballast Water Treatment System (선박 평형수 처리 시스템의 안드로이드 원격 모니터링 시스템)

  • Choi, Hwi-Min;Seo, Ji-No;Lee, Kwang-Seob;Kim, Seon-Jong;Kim, Joo-Man
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.15 no.6
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    • pp.217-224
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    • 2015
  • In this paper, I describe a system for remote monitoring of devices Android-based sensor data recorded during the operation of the ballast water treatment system. The proposed remote monitoring system is Designed and implemented when a problem occurs in the ballast water treatment system installed in the vessel, provide information if you are unable to determine the cause in the field or engineer dispatch request of external. System developed is composed of a server holding the sensor data information collected from the vessel and a mobile device that is not bound to time and place. The transmission of sensor data between mobile devices and server, and is implemented by TCP/IP to transmit information securely. System is composed of request to the server from the mobile device after the user inputs the input values, to transmit the sensor data. The device provides the information of the sensor with a high level of importance to the user. Through the remote monitoring sensor information of the ballast water treatment system, the system is made to predict the failure of the sensor.

Decision Making Experience on Breast Reconstruction for Women with Breast Cancer (한국 유방암 여성들의 유방재건술에 관한 의사결정 경험)

  • Yi, Myungsun;Joung, Woo Joung;Park, Eun Young;Kwon, Eun Jin;Kim, Haejin;Seo, Ji Young
    • Journal of Korean Academy of Nursing
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    • v.46 no.6
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    • pp.894-904
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    • 2016
  • Purpose: The purpose of this study was to explore decision making experiences of Korean women with breast cancer who underwent breast reconstruction with/after a mastectomy. Methods: Data were collected during 2015-2016 through individual in-depth interviews with 10 women who had both mastectomy and breast reconstruction, and analyzed using phenomenological method to identify essential themes on experiences of making a decision to have breast reconstruction. Results: Five theme clusters emerged. First, "expected loss of sexuality and discovery of autonomy" illustrates various aims of breast reconstruction. Second, "holding tight to the reputation of doctors amid uncertainty" specifies the importance of a trust relationship with their physician despite a lack of information. Third, "family members to step back in position" describes support or opposition from family members in the decision making process. Fourth, "bewilderment due to the paradox of appearance-oriented views" illustrates paradoxical environment, resulting in confusion and anger. Lastly, "decision to be made quickly with limited time to oneself" describes the crazy whirling process of decision making. Conclusion: Findings highlight aims, worries, barriers, and facilitators that women with breast cancer experience when making a decision about breast reconstruction. Deciding on breast reconstruction was not only a burden for women in a state of shock with a diagnosis of breast cancer, but also an opportunity to decide to integrate their body, femininity, and self which might be wounded from a mastectomy. These findings will help oncology professionals provide effective educational counselling before the operation to promote higher satisfaction after the operation.

A Study of Strategy plan for the Improvement on menu marketing Commoditization. (메뉴 상품 마케팅 전략방안에 관한 연구)

  • 김장익;홍철희
    • Culinary science and hospitality research
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    • v.4
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    • pp.347-367
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    • 1998
  • It is difficult to make which customers want in restaurant industry because of IMF situation. Therefore, utilization of service marketing is needed by best effect through least investment in restaurant industry. The background of restaurant industry is not directly related to the improvement of tourism industry. We should give a hand to tourism and restaurant industry by holding international events. so the way of thinking among people is changing. And importing of famous foreign brand and opening shops are accellerating the improvement of tourism and restaurant industry. In this perspective, improvement factors of restaurant industry are as follows : the increase of pst time, the increase of disposable income, the increase of woman's having jobs and double income, requirement of people about health food, the increase of nuclear family, and the change of viewpoint among people. This restaurant industry is service industry, and it sells invisible service except the aspect of selling menu. In addition, in terms of menu, price reduction strategy should be done by cost reduction and restructuring. The ultimate purpose of marketing is to increase sales and to do this we should increase the number of customers in shops. That means we should create new customers and try to attract customers who used to be regular in the shops. Therefore, the demonstration of management ability and positive reaction is really needed. So the most important things in marketing are as follows: proper strategy for double consumption, increasing the number of customers through new specific menu, menu life cycle according to menu item, menu development by considering customer, making recipe, enhancement of product quality and cost reduction by customer's opinion. We should concentrate on national menu first, and try to develop menu for international market. It is absolutely needed that we set up the menu product strategy through menu marketing with various products and constant study related to menu marketing is to be done.

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