• Title/Summary/Keyword: Accelerated life test

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Cross-Cultural Studies in Fashion Marketing Discipline (패션마케팅 영역에서의 비교문화적 연구의 경향)

  • Cho, Yun-Jin;Yang, Su-Zin;Kim, Eun-Young;Choo, Ho-Jung
    • Journal of the Korean Society of Clothing and Textiles
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    • v.30 no.8
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    • pp.1312-1322
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    • 2006
  • A recent accelerated globalization has changed every aspect of consumers' life on the globe, thus understanding the similarity and the difference among people in the world became the crucial element of business for many global companies. As one of the most globalized industries in Korea, fashion businesses also require urgent assistance of academics in understanding global consumers. This study aimed to analyze cross-cultural fashion marketing studies published in two respectful journals in fashion studies: Journal of Korean Society of Clothing and Textiles and Journal of the Korean Society of Costume. Four researchers independently searched the target journals to locate studies using cross-cultural approaches. A total of 45 cross-cultural studies published in two journals between 1977 and 2005 were found and analyzed. The major findings could be summarized as followed. First, the US was the most frequently studied country followed by China, Japan, Hong Kong and others. Second, popular subjects of cross cultural studies in fashion marketing were fashion marketing environment and management rather than consumer psychology. Third, about 78% of the sampled studies were using quantitative approach, and statistical methods such as factor analysis, t-test, ANOVA, and $X^2$ analysis were commonly used. Finally, problems in sampling methods, translation of scales, and equivalence of concept, measure and sample were analyzed. Suggestions for future cross-cultural studies were discussed.

Assessment and Applications of Multi-Degradable Polyethylene Films as Packaging Materials

  • Chung, Myong-Soo;Lee, Wang-Hyun;You, Young-Sun;Kim, Hye-Young;Park, Ki-Moon;Lee, Sun-Young
    • Food Science and Biotechnology
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    • v.15 no.1
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    • pp.5-12
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    • 2006
  • Degradation performance of environmentally friendly plastics that can be disintegrated by combination of sunlight, microbes in soil, and heat produced in landfills was evaluated for use in industries. Two multi-degradable master batches (MCC-101 and MCC-102 were manufactured, separately mixed with polyethylene using film molding machine to produce 0.025 mm thick films, and exposed to sunlight, microbes, and heat. Low- and high-density polyethylene (LDPE and HDPE) films containing MCC-101 and MCC-102 became unfunctional by increasing severe cleavage at the surface and showed high reduction in elongation after 40 days of exposure to ultraviolet light. LDPE and HDPE films showed significant physical degradation after 100 and 120 days, respectively, of incubation at $68{\pm}2^{\circ}C$. SEM images of films cultured in mixed mold spore suspension at $30^{\circ}C$ and 85% humidity for 30 days revealed accelerated biodegradation on film surfaces by the action of microbes. LDPE films containing MCC-l01 showed absorption of carbonyls, photo-sensitive sites, at $1710\;cm${-1}$ when exposed to light for 40 days, whereas those not exposed to ultraviolet light showed no absorption at the same frequency. MCC-101-based LDPE films showed much lower $M_w$ distribution after exposure to UV than its counterpart, due to agents accelerating photo-degradation contained in MCC-101.

Investigation of Degradation Mechanism of Rabeprazole with Solid State Pharmaceutical Excipients

  • Ren, Shan;Tran, Thao Truong-Dinh;Tran, Phuong Ha-Lien;Rhee, Yun-Seok;Lee, Beom-Jin
    • Journal of Pharmaceutical Investigation
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    • v.40 no.6
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    • pp.367-372
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    • 2010
  • Rabeprazole sodium (RPN) is known to be very unstable at acidic condition or some acidic pharmaceutical excipients such as acrylic acid polymer (carbomer 934) with carboxylic acids. Thus, degradation mechanism of binary blends of rabeprazole with pharmaceutical excipients in a solid state without using solvents at three different ratios (3:1, 1:1 and 1:3) was investigated using Fourier transform infrad (FTIR) spectroscopy. Alkalizer (MgO), neutral hydroxypropymethylcellulose (HPMC 4000) were also tested for comparison. The binary blends were stored under accelerated conditions ($40^{\circ}C$/75% relative humidity) for two weeks. The concentration of thioether rabeprazole from the binary blends with acidic carbomer 934 increased as the rabeprazole concentration decreased. In addition, the degradation half-life of rabeprazole as well as the relative peak area ratios obtained from FTIR spectra of S=O stretching at $1094.1\;cm^{-1}$ decreased consistently as the fraction of carbomer 934 increased due to its sensitivity between the basic benzimidazole nitrogen and carboxylic acid group of carbomer 934. The physical appearance also turned into strong brown color in the presence of carbomer 934. In contrast, there were no significant changes in the degradation kinetics of rabeprazole with MgO and HPMC 4000 in a solid state. This present study demonstrated that the solid-state compatibility test with the aid of HPLC chromatographic and FTIR spectral analyses could offer a valuable methodology to select suitable pharmaceutical excipients and to elucidate the degradation mechanism of RPN for drug formulations at the early formulation stages.

Development of Road Tunnel Ventilation System with Electrostatic Precipitator (도로터널용 전기집진시스템 개발)

  • Kim, Jong-Ryul;Weon, Jong-Oung
    • Proceedings of the SAREK Conference
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    • 2008.11a
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    • pp.80-83
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    • 2008
  • As SOC (Social Overhead Capital) has been expanded, the highway road construction has been accelerated and city road system has been more complicated. So, long road tunnels have been increased and traffic flow rate also has been raised. Accordingly, the exhausting gas of vehicle cars seriously deteriorates the tunnel inside air quality and driving view. In order to improve tunnel inside air quality, we may need to introduce a compulsory ventilation system as well as natural ventilation mechanism. The natural ventilation mechanism is enough for short tunnels, meanwhile longer tunnels require a specific compulsory ventilation facility. Many foreign countries already have been devoting on development of effective tunnel ventilation system and especially, some European nations and Japan have already applied their developed tunnel ventilation system for longer road tunnels. More recently, as the quality of life improved, our concerns about safety of driving and better driving environment have been increased. In order to obtain clearer and longer driving view, we are more interested in EP tunnel ventilation system in order to remove floating contaminants and automobile exhaust gas. Evan though it's been a long time since many European countries and Japan applied more economical and environment-friendly tunnel ventilation system with their self-developed Electrostatic Precipitator, we are still dependant on imported system from foreign nations. Therefore, we need to develop our unique technical know-how for optimum design tools through validity investigation and continuous possibility examination, eventually in order to localize the tunnel ventilation system technology. In this project, we will manufacture test-run products to examine the performance of system in order to develop main parts of tunnel ventilation system such as electrostatic precipitator, high voltage power generator, water treatment system, etc.

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Effect of Arginine or Sodium Phosphate Dibasic on the Stability of Omeprazole in Aqueous Solution (아르기닌 또는 인산일수소나트륨이 수용액중에서 오메프라졸의 안정성에 미치는 영향 비교)

  • Shim, Chang-Koo;Han, Yong-Hae;Woo, Jong-Soo;Lee, Chang-Hyun
    • Journal of Pharmaceutical Investigation
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    • v.23 no.4
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    • pp.225-229
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    • 1993
  • The stability of omeprazole in the aqueous solutions containing arginine or sodium phosphate dibasic(SPD) was examined at 30, 40 and $50^{\circ}C$. Arginine or anhydrous SPD was added to omeprazoie solution ($200{\mu}g/\;ml$ in distilled water) to yield $100{\mu}g/\;ml$ concentration of each. Then, the solution was kept at 30, 40 or $50^{\circ}C$ for 90 hrs. Aliquots of the solution were withdrawn at specified time intervals and assayed by HPLC for intact omeprazole. The remaining percentage-time curves revealed that omeprazole was degraded rapidly as funtions of time and temperature following pseudo first-order kinetics. The rate constant in the SPD solution was much higher than in the arginine solution. In other words. the degradation half-lives of omeprazole at $30^{\circ}C$, for example, was 148 and 76 hr in arginine and SPD solutions respectively. The initial pH of the solution containing $100{\mu}g/\;ml$ of arginine or SPD was 9.7 or 8.7, respectively. Since omeprazole is more stable as the pH of its solution becomes more alkaline, the longer half-life of omeprazole in arginine solution could be explained by the more alkaline characteristics of arginine than SPD in the solution. The activation energy necessary for the degradation reaction was almost identical in both solutions, indicating similar degradation mechanisms of omeprazole in the solutions. In conclusion, omprazole was more stable in the presence of arginine than of SPD.

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An Evaluation of Moisture Sensitivity of Asphalt Concrete Pavement Due to Aging (노화에 따른 아스팔트 콘크리트 포장의 수분민감성 평가)

  • Kim, Kyungnam;Kim, Yooseok;Kim, Nakseok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.39 no.4
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    • pp.523-530
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    • 2019
  • Pavement distress and traffic accidents are caused by pot-hole. In addition, direct and indirect damages of road users are increasing, such as loss of life due to personal injury and damage to vehicles. Generally, the asphalt concrete pavements are continuously aging from the production process to the terminal performance period. Aging causes stripping due to cracks and moisture penetration and weakening the pavement structure to induce pot-hole. In this study, adhesion performance and moisture sensitivity were evaluated according to aging degree in order to investigate the effect of aging on asphalt pavement. As a result of the study, the viscosity of the asphalt binder was increased with aging and the bond strength of the aged was increased 2~3 times than that of the unaged. The results of accelerated aging test showed an increases in indirect tensile strength and the increase in the TSR (Tensile Strength Ratio) by 4.2~8.9 %. As a result, it is noted that the anti-stripping and adhesion performances of the aged asphalt concrete are improved compared to the unaged one under the aging conditions of asphalt binder coated on aggregates.

Research on aging-related degradation of control rod drive system based on dynamic object-oriented Bayesian network and hidden Markov model

  • Kang Zhu;Xinwen Zhao;Liming Zhang;Hang Yu
    • Nuclear Engineering and Technology
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    • v.54 no.11
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    • pp.4111-4124
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    • 2022
  • The control rod drive system is critical to the reactor's reliable operation. The performance of its control system and mechanical system will gradually deteriorate because of operational and environmental stresses, thus increasing the reactor's operational risk. Currently there are few researches on the aging-related degradation of the entire control rod drive system. Because it is difficult to quantify the effect of various environmental stresses and establish an accurate physical model when multiple mechanisms superimposed in the degradation process. Therefore, this paper investigates the aging-related degradation of a control rod drive system by integrating Dynamic Object-Oriented Bayesian Network and Hidden Markov Model. Uncertainties in the degradation of the control system and mechanical system are addressed by using fuzzy theory and the Hidden Markov Model respectively. A system which consists of eight control rod drive mechanisms divided into two groups is used to demonstrate the method. The aging-related degradation of the control rod drive system is analyzed by the Bayesian inference algorithm based on the accelerated life test data, and the impact of different operating schemes on the system performance is also investigated. Meanwhile, the components or units that have major impact on the system's performance are identified at different operational phases. Finally, several essential safety measures are suggested to mitigate the risk caused by the system degradation.

Dry-heat Treatment Effect for Seed Longevity Prediction in Rice Germplasm (벼 유전자원의 저장수명 예측을 위한 건열처리 효과)

  • Na, Young-Wang;Baek, Hyung-Jin;Choi, Yu-Mi;Lee, Sok-Young;Lee, Jung-Ro;Chung, Jong-Wook;Park, Yong-Jin;Kim, Seok-Hyeon
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.59 no.3
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    • pp.230-238
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    • 2014
  • The purpose of this study was to develop the cost-effective and efficiency seed longevity prediction method of rice (Oryza sativa L.) germplasm for viability monitoring. To find an optimum predicting method for rice seed longevity at genebank, an accelerated ageing (AA) test, a controlled deterioration (CD) test and a dry-heat treatment (DHT) were conducted to the four groups of rice germplasm based on ecotype, such as Indica, Japonica, Javanica and Tongil type. Among the three artificial aging treatments, the dry-heat treatment of 36 hours at $90^{\circ}C$ is suggested as a routine predictive test method of rice germplasm longevity at a genebank. The distribution of germination rate on 3,066 accessions which conserved 26.5 years at $4^{\circ}C$ showed similar trend with the result of distribution by dry-heat treatment at $90^{\circ}C$ on 36 hours using 106 accessions of rice selected samples which composed four ecotype groups. The results show that the dry-heat treatment affect not only predicting the rice seed longevity but also determining effective interval for monitoring germination of rice germplasm in genebanks.

An Experimental Study on the Machinability Influenced by Coated and Uncoated Tips, and Damping Device in Turning (선삭에 있어서의 피복, 비피복팁 및 방진장치가 절삭성에 미치는 영향에 관한 실험적 연구)

  • Nam, Joon-Woo
    • Journal of the Korean Society for Precision Engineering
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    • v.3 no.2
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    • pp.62-75
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    • 1986
  • An experimental investigation of the machining characteristics such as cutt- ing resistance, surface roughness and tool wear in turning the test pieces of SM45C steel with both coated and uncoated carbide tool tips under various cutting conditions was conducted. Also a specially designed simple vibration damping device was experimentally evaluated for its effectiveness on machined surface roughness and a vibration test was conducted to confirm its ability to reduce the amplitude. Based on these tests finding, the following conclusions are made; 1. The cutting resistance($\textrm{p}_{1}$) increases as the depth of cut(d) increases at fixed feed rate(f) over the cutting speed(v) range of 43-226 m/min and p decreses about 18% average when V is increased for fixed d and f. At V= 226m/min, $\textrm{p}_{1}$/for A, C tips are about the same level but $\textrm{p}_{1}$ for B tip is 15% less than A, C tips. 2. The specific cutting resistance(Ks) at V=226 m/min was derived for A, B, C tips respectively and the value of Ks for B rip is about 20% less than A, C tips. 3. The surface roughness(Ra) improves significantly as the cutting speed(V) is increased and this effect was greater when V>100 m/min. On the other hand, Ra deteriorates as the feed rate(f) is increased and this trend was accelerated when f>0.3 mm/rev. With regard to the difference of Ra values among A, B, C tips, at V=226m/min, d=0.4mm, and f=0.31-0.61mm/rev, Ra values for B.C tips are about 17% less than tip A. 4. The experimental tool wear equations were derived for A, B, C tips and from these equations, the tool life($\textrm{T}_{\textrm{L}}$) baced on the I.S.O. criteria was calculated to be $\textrm{T}_{\textrm{L}}$<$\textrm{T}_{\textrm{LB}}$<$\textrm{T}_{\textrm{LC}}$ for both flank wear($\textrm{V}_{\textrm{B}}$) and boundary wear($\textrm{V}_{\textrm{N}}$). Hence, the coated tips are superior to the uncoated tip and tip C is considered to be the best. 5. The cutting resistance may be slightly reduced and the surface rounghness improved when the damper is used especially when V>100 m/min. Therefore this damping device is considered to be effective and practical. The experimental surface roughness equations were also derived. Based on the vibration test, it is established that the surface roughness improvement was the result of amplitude reduction made possible by the damper.

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Design Technique for Durability Improvement of Military Vehicle Clutch System (군용차량 클러치 내구수명 향상에 대한 연구)

  • Shin, Cheol-Ho;Kang, Tae-Woo;Kim, Sung-Gon;Kim, Seon-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.10
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    • pp.117-124
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    • 2019
  • Military Vehicles of the Korean army had been developed before 2004 and used manual transmissions. Manual transmissions contain a clutch system regulating the force from engine to transmission. In this study, a 2.5-ton military vehicle's clutch system was investigated. The existing clutch system had the characteristics that need to adjust the clearance between the clutch cover and release bearing. Improper clearance led to early wear of the clutch disk and failure of the clutch cover. To solve these problems, an improved clutch system was suggested and tested. The improved clutch system contains auto adjustment of the clearance and an enhanced clutch disk. To verify the improved clutch systems, 2 stage tests were conducted: an accelerated life test of the clutch system, and a driving test by trainee of driving more than 3,000km. As a result, the problems caused by the improper clearance adjustment were solved and this design was verified.