• Title/Summary/Keyword: T74

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7XXX계 단조재의 피로 및 파괴인성 개선

  • 황성주;임재규;이오연;손영일;은일상;신돈수
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 1995.11a
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    • pp.195-203
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    • 1995
  • 본 연구는 강도와 인성이 우수한 7175Al 단조재의 국산화 개발을 위하여 기존 7XXX합금의 제조공정(일반공정)을 적용한 7075-T6/T73, 7050-774 및 7175-T74 단조재와 중간열처리, 용체화처리 등을 고온처리하는 특수제조 공정을 적용한 7175-T74 단조재의 강도, 파괴인성($K_IC$) 및 피로특성을 비교 평가하였다. 특수공정을 적용한 7175S-T74 단조재는 일반공정의 7075-T73, 7050-T74 및 7175-T74재보다 강도, 파괴 인성 및 피로특성이 향상되었다. 이것은 주조시 응고과정에서 형성되는 2차상입자의 감소와 특수공정의 적용효과에 기인하는 것으로 판단된다.

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대형 복합재 연소관 Boss용 Al 합금 국산화 개발

  • 손영일;임성택;은일상;장창범
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 1995.05a
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    • pp.127-138
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    • 1995
  • 대형 복합재 연소관 금속 보스용 고강도 알루미늄 합금 7175-T74를 개발하기 위하여, 고순도 7175 합금을 이용하여 링롤 단조법으로 대형링을 제조하였으며, 열처리와 가공 조건을 정밀제어한 특수공정을 적용하여 기존의 재료와 재질 특성을 비교 분석하였다. 분석결과 특수공정의 7175S-T74는 기존의 7175-T74 및 7075-T73에 비해 2차상 입자의 분률이 작고, 동일한 SCC특성(38% IACS) 수준에서 강도와 파괴인성이 동시에 증가한 이상적인 강도-인성-SCC 조합특성을 가졌다. 이는 특수공정에서의 고온열처리에 의한 2차상 입자의 재고용과 그에 따른 석출량 증가 때문이며, 결국 7175 합금, 링롤단조 그리고 T74 특수공정을 조합 적용하면 구조적 신뢰성과 경제성 면에서 유리한 보스용 대형링을 개발할 수 있다.

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Correlation of Korean Elderly Dental Health Capacity and Preferred Foods (한국 노인의 치아건강도와 선호식품과의 관련성)

  • Ju, On-Ju;Kim, In-Ja
    • Journal of dental hygiene science
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    • v.15 no.6
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    • pp.712-720
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    • 2015
  • The purpose of this study is to examine whether any correlation exists between the dental health capacity and preferred foods of Korean senior citizens over the age of 65 years. The 5th Korean National Health and Nutrition Survey were used. Tissue health index (T-health), Sound teeth (ST), Functioning teeth index (FS-T), Present teeth (PT), and Missing teeth (MT) were used as variables to assess the dental health capacity of the elderly. Preferred foods of the elderly included 63 foods that were categorized as cereals, pulses and roots, meat and poultry, fish, vegetables, sea algae, fruits, milk and dairy products, cream and sugar, and other foods. For data analysis, the weighted average was taken into consideration to generate planning files, and then complex sample analysis were conducted. For statistical analysis, frequency analysis, t-test, one-way ANOVA, and compound specimen linear regression analysis were conducted. T-health score was significantly high in the group with high preference for cereals, fruits, and other foods. In terms of age and economic status, 65~69 years, 70~74 years, and mid to low range in the income ranges scored high in T-health. ST score was significant in the group that preferred cereals, other foods; the corresponding demographic profiles represent 65~69 years, 70~74 years, and the mid-range income communities. FS-T was significant in relation with a preference for fruits, creams and sugars, other foods; the scores were also high for 65~69 years, 70~74 years, and mid-low to low income groups. PT and MT were significant in the group that preferred cereals and fruits; the same applied for 65~69 years, 70~74 years, and mid-low to low income individuals (p<0.05). Food preferences seemed to vary depending on the dental health state of the elderly, and the dental health state of the elderly may act as a risk factor for nutritional imbalance.

A study on the heat treatment processing of 7050 aluminum alloy (7050Al 합금의 열처리공정 개발에 관한 연구)

  • Lee, H.S.;Nam, T.W.;Lee, B.K.
    • Journal of the Korean Society for Heat Treatment
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    • v.9 no.2
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    • pp.139-146
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    • 1996
  • The aero-industry is union industry which includes a research development type, a knowledge accumulation type and a developed country type. The aero-industry of Korea is in semi-developed type stage but departed later than that of other country such as Taiwan, Indonesia etc. Therefore, the necessity of domestic airplane material is required. This study on 7050Al extruded alloy aims to suggest an adequate heat treatment conditions of T73, T74 and T76. The results of this study show that; 1. The optimum conditions of T7x heat treatment in extruded 7050Al alloy show this; $$T73:121^{\circ}C{\times}7hr+177^{\circ}C{\times}14hr$$. $$T74:121^{\circ}C{\times}7hr+177^{\circ}C{\times}10hr$$. $$T76:121^{\circ}C{\times}7hr+163^{\circ}C{\times}21hr$$. 2. The 2nd step aging heat treatment such as T73, T74 and T76 etc. is efective in 7050Al alloy but the variation otf microstructure and mechanical property with dispersive inclusions produced for extrusion process causes some troubles. Accordingly, in order to produce a good 7050Al alloy, a careful attention is needed in manufacturing process.

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The Effect of Jujubi, Ginseng and Garlic on the TBA value and microbial count of Samgaetang during Refrigerated Storage (대추, 마늘, 수삼이 냉장 저장한 삼계탕의 산패와 미생물증식에 미치는 영향)

  • 박옥주;김나영;한명주
    • Korean journal of food and cookery science
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    • v.19 no.5
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    • pp.591-595
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    • 2003
  • The objective of this study was to evaluate the effects of ingredients on the change of Samgyetang quality during refrigerated storage. The Samgyetang was prepared with five treatments. The five treatments were chicken cooked alone (Tl), cooked with jujubi, ginseng and garlic (T2), cooked with jujubi (T3), cooked with ginseng (T4) and cooked with garlic (T5). The TBA values of the Samgyetang over 4 days of refrigerated storage were T1(0.89) > T3(0.74) T5(0.74) > T4(0.57) > T2(0.42). The total plate counts of the Samgyetang in the T2 and T3 treatments were lower than with the other treatments. The coliform counts of the Samgyetang in the T2 and T5 treatments were lower than with the other treatments. The results from this study showed that ginseng had an antioxidant activity, jujubi lowered the total plate count and garlic lowered the coliform count in refrigerated Samgyetang. Therefore, the addition of these ingredients maintains the quality of Samgyetang during refrigerated storage.

Improvement of Fracture Toughness in 7XXX Series Aluminum Alloy Forings (7XXX계 알루미늄합금 단조재의 파괴인성 개선)

  • Song, K.H.;Lee, O.H.
    • Journal of the Korean Society for Heat Treatment
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    • v.11 no.3
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    • pp.200-206
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    • 1998
  • The aim of this study is to investigate the effect of impurity level and fabrication processes on the strength, impact and fracture toughness of 7075, 7050 and 7175 aluminum alloy forgings. A specially processed 7175S-T74 aluminum forgings was superior to a conventionally processed 7075-T73, 7050-T74 and 7175-T74 aluminum forgings in both strength and toughness. The reduction of impurity level of iron and silicon has significantly diminished the size and volume fraction of second phase particles such as $Al_7Cu_2Fe$ and $Mg_2Si$. A further reduction of the amount of second phase particles has been observed by applying a special fabrication process. This phenomena result from the application of intermediate soaking at higher temperature and more sufficiant hot working temperature than that of a conventional processing.

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Application development of 7050Al alloy in small arms. (소화기용 7050 Al합금소재의 적용성 개발)

  • 김헌규;최중환
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.1093-1097
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    • 1996
  • The Substitution development of 7075-T6 Al alloy to 7050-T74 Al alloy in small arms to improve anti-stress corrosion cracking was processed along with mass productivity consideration. To meet 7050 Al alloy material characteristics Indirect extrusion type was adopted and local heating above recrystalization temperature in forging process had to be avoided. The T74 aging treatment was 12$0^{\circ}C$ -6hrs and 175$^{\circ}C$ -12hrs and was appropriate for both machanical and anti-cohesion properties. In accessment of field application test 7050Al alloy made parts of small arms showed equivalent or better performance than 7075 Al alloy.

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Influence of 120 kDa Pyruvate:Ferredoxin Oxidoreductase on Pathogenicity of Trichomonas vaginalis

  • Song, Hyun-Ouk
    • Parasites, Hosts and Diseases
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    • v.54 no.1
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    • pp.71-74
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    • 2016
  • Trichomonas vaginalis is a flagellate protozoan parasite and commonly infected the lower genital tract in women and men. Iron is a known nutrient for growth of various pathogens, and also reported to be involved in establishment of trichomoniasis. However, the exact mechanism was not clarified. In this study, the author investigated whether the 120 kDa protein of T. vaginalis may be involved in pathogenicity of trichomonads. Antibodies against 120 kDa protein of T. vaginalis, which was identified as pyruvate:ferredoxin oxidoreductase (PFOR) by peptide analysis of MALDI-TOF-MS, were prepared in rabbits. Pretreatment of T. vaginalis with anti-120 kDa Ab decreased the proliferation and adherence to vaginal epithelial cells (MS74) of T. vaginalis. Subcutaneous tissue abscess in anti-120 kDa Ab-treated T. vaginalis-injected mice was smaller in size than that of untreated T. vaginalis-infected mice. Collectively, the 120 kDa protein expressed by iron may be involved in proliferation, adhesion to host cells, and abscess formation, thereby may influence on the pathogenicity of T. vaginalis.

A Case of Supracricoid Partial Laryngectomy in T4 Supraglottic Carcinoma (T4 병기 성문상암에서 상윤상후두부분적출술 1례)

  • 김민식;박경호;이일로;조승호
    • Korean Journal of Bronchoesophagology
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    • v.7 no.1
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    • pp.66-70
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    • 2001
  • Supracricoid partial laryngectomy (SCPL) has been performed in selected patients with transglottic carcinoma of larynx who are not amenable to classically conservative Partial laryngectomy. We have applied this procedure for the complete removal of carcinoma and the satisfactory recovery of function in 74 supraglottic laryngeal cancer Patient with thyroid cartilage invasion. The 65-year-old man with supraglottic squamous carcinoma with thyroid cartilage invasion (74 stage) was treated by SCPL with bilateral lateral neck dissection. The part of larynx and whole thyroid cartilage with tumor invasion was completely removed with covering thyrohyoid muscle and fascia. External perichondrium of the thyroid cartilage containing carcinoma was not exposed from the overlying muscle and fascia on postoperative pathological examination. We confirmed the invasion of thyroid cartilage histopathologically. Tumor was confined in the specimen and the safety margin was proved in all direction. Postoperative course and functional results were uneventful. SCPL can be applied in selected cases of locally advanced 74 laryngeal cancer.

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