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Characteristic of Friction on Texturing Bearing Steel with Ultrasonic Hole Machine
Mijung Shin(신미정),Angga Senoaji H,SoonHong Kwon(권순홍),SungWon Chung(정성원),SoonGoo Kwon(권순구),JongMin Park(박종민),JongSoon Kim(김종순),WonSik Choi(최원식) 한국트라이볼로지학회 2015 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.31 No.1
We carry out experiments to characterize textured bearing steel with varying hole density and depth. Textured surface is believed to reduce the friction coefficient, and improve performance and wearing caused by third-body contact. We employ three lubrication regime conditions based on the Stribeck curve: boundary lubrication, mixed lubrication, and hydrodynamic lubrication. Ultrasonic machining is an untraditional machining method wherein abrasive grit particles are used. The hammering process on the work piece surface by abrasive provides the desired form. In this study, we create multi-holes on the bearing steel surface for texturing purposes. Holes are formed by an ultrasonic machine with a diameter of 0.534 mm and a depth of about 2-4 mm, and they are distributed on the contact surface with a density between 1.37-2.23%. The hole density over the surface area is an important factor affecting the friction. We test nine types of textured specimens using four times replication and compare them with the untextured specimen using graphs, as well as photographs taken using a scanning electron microscope. We use Analyzes variant in this experiment to find the correlation between each pair of treatments. Finally, we report the effect of hole density and depth on the friction coefficient.
Characteristic of Friction on Texturing Bearing Steel with Ultrasonic Hole Machine
Shin, Mijung,H., Angga Senoaji,Kwon, SoonHong,Chung, SungWon,Kwon, SoonGoo,Park, JongMin,Kim, JongSoon,Choi, WonSik Korean Tribology Society 2015 한국윤활학회지(윤활학회지) Vol.16 No.4
We carry out experiments to characterize textured bearing steel with varying hole density and depth. Textured surface is believed to reduce the friction coefficient, and improve performance and wearing caused by third-body contact. We employ three lubrication regime conditions based on the Stribeck curve: boundary lubrication, mixed lubrication, and hydrodynamic lubrication. Ultrasonic machining is an untraditional machining method wherein abrasive grit particles are used. The hammering process on the work piece surface by abrasive provides the desired form. In this study, we create multi-holes on the bearing steel surface for texturing purposes. Holes are formed by an ultrasonic machine with a diameter of 0.534 mm and a depth of about 2-4 mm, and they are distributed on the contact surface with a density between 1.37-2.23%. The hole density over the surface area is an important factor affecting the friction. We test nine types of textured specimens using four times replication and compare them with the untextured specimen using graphs, as well as photographs taken using a scanning electron microscope. We use Analyzes variant in this experiment to find the correlation between each pair of treatments. Finally, we report the effect of hole density and depth on the friction coefficient.
감마선과 Methyl Bromide 처리가 녹두의 살충 및 이화학적 특성에 미치는 영향
노미정(Mijung Noh),권중호(Joong-Ho Kwon),권용정(Yong-Jung Kwon),허은엽(Eun-Yub Huh),권용순(Yong-Soon Kwon),변명우(Myung-Woo Byun) 한국식품영양과학회 2001 한국식품영양과학회지 Vol.30 No.3
녹두의 가해해충 살충방법을 연구할 목적으로 현행 검역해충 살충방법인 methyl bromide(MeBr) 훈증처리와 감마선 조사에 의한 살충효과와 몇 가지 이화학적 특성에 미치는 영향을 비교하였다. 국내산 녹두의 가해해충은 팥바구미(Callosobruchus chinensis Linne)로 확인되었으며, 살충처리 후 5일째에 MeBr 처리는 완전한 살충효과를 보였다. 같은 시기에 3 kGy 이상의 감마선 조사는 유충에 대하여 완전한 살충효과를 보였고, 2 kGy 조사구에서도 약 90%의 살충률을 나타내었다. 그리고 녹두의 성충은 유충에 비해 방사선 감수성이 큰 것으로 나타나 처리 후 10~15일 경에 두 충태 모두 1 kGy 조사구에서도 100%의 누적살충률을 보였다. 살충조건에서 녹두의 이화학적 품질특성을 비교해 본 결과, 질소용해도, TBA가, 총아미노산 및 지방산 조성과 함량은 2.5 kGy 조사구 및 MeBr 처리구에서 대조구와 유의적인 차이를 보이지 않았다. 그러나 녹두의 기계적 색도는 MeBr 훈증처리에 의해 명도의 감소와 적색도 및 황색도의 증가로 전반적인 색차(ΔE)에서 느끼는 정도(NBS 2.61~2.94)의 색 변화를 가져왔다. Comparative effects of gamma irradiation and methyl bromide (MeBr) fumigation on disinfestation and physicochemical attributes of mung bean were investigated. Insects in domestic mung bean were identified to be Callosobruchus chinensis Linne. In a disinfestation test, MeBr showed 100% disinfestation effect on larva and adult at 5th day after treatments, while irradiation dose above 3 kGy was effective for disinfesting all larva at that time. Adults were more sensitive to radiation than larva. Around 1 kGy was enough to control larva and adult in mung bean following 10 to 15 days of irradiation. In physicochemical properties of treated samples, nitrogen solubility, TBA value, amino acid and fatty acid compositions were not different among the control, 2.5 kGy-irradiated and MeBr-fumigated samples. MeBr fumigation caused the decrease in lightness (Hunter’s L value) and the increase in redness (a value) and yellowness (b value), thereby resulting in overall color difference (ΔE) in a noticeable level (NBS 2.61~2.94).
Expression of the VP2 protein of canine parvovirus 2b using a baculovirus expression system
Min-Ji Kim, Seong-In Lim, MiJung Kwon, Min Ji Kim, Eui Hyeon Lim, Bang-hun Hyun, Yoon-Hee Lee 한국예방수의학회 2023 예방수의학회지 Vol.47 No.3
Canine parvovirus-2 (CPV-2) has been reported worldwide as a major pathogen associated with acute hemorrhagic enteritis. The disease is a major infectious cause of death, particularly in young dogs. The earliest type of CPV-2 was replaced with three main subspecies, CPV-2a, CPV-2b, and CPV-2c, within a few years. Vaccination is carried out regularly, but the emergence of antigenic variants and the influence of maternal antibodies have limited the efficacy of commercial vaccines. New vaccines, such as the subunit vaccine, have been developed for alternative, safe, and effective vaccination. The baculovirus expression vector system (BEVS) is an excellent eukaryotic expression system with a high-level expression of foreign proteins and the ability of post-translational modification. Therefore, it is used widely to produce recombinant protein and subunit vaccines. In this study, the VP2 protein of CPV-2b cloned in the gateway vector system was generated using a baculovirus expression system in Spodoptera frugiperda (SF9) insect cells. Hemagglutination assay (HA) titers (2⁴) were obtained, and the expression was detected in 6-His tagged VP2 and monoclonal antibody (mAb) against CPV-2 by western blotting. The VP2 protein of CPV-2b expressed in this study may provide a basis for a clinical diagnosis and vaccination applications for CPV-2.
Kwon, Man Jae,Lee, Giehyeon,Hwang, Yun Ho,Lee, Mijung,Yang, Jung-Seok Springer-Verlag 2016 Water, Air and Soil Pollution Vol.227 No.9
<P>The effects of soil micro-particles and micropores on the release of total petroleum hydrocarbons (TPH) were investigated using long-term weathered, TPH-contaminated soil samples. The TPH concentrations were analyzed using various extraction schemes (i.e., total extraction, weak extraction, solvent extraction with or without ultrasound). The particle size distribution (<2 mm, 0.063-2 mm, <0.063 mm), micro-pore volume (<0.38 mm), and TPH fraction (C8-14, C16-28, C30-40) of selected samples were also determined to better understand the factors controlling TPH release from contaminated soils. TPH concentrations varied greatly among different fractions of each soil sample, but were highest in the micro-fraction (<0.063 mm) of each sample. In weathered soil samples, TPH was not only weakly or strongly adsorbed on soil particles, but also trapped in soil micro-pores. Moreover, heavier fractions of TPH were released slowly and lesser extent from contaminated soils. Results showed that the solvent extraction method with and without ultrasound could be used to assess relative binding strength of TPH to contaminated soils. These findings imply that to achieve a remediation goal, some contaminated soils require only relatively mild extraction with solvent, but soils with TPH trapped in micro-pores require physical destruction along with chemical extraction.</P>
Mijung Park,Ji Um,So Hyun Kim,Jiseon Yoon,Yeonjae Lee,Jiyeong Kwon,Seonhee Baek,Dong Yeon Kim 한국아동간호학회 2023 Child Health Nursing Research Vol.29 No.1
Purpose: This study investigated correlations between the actual sleep time 24 hours prior to an examination and the time to achieve chloral hydrate sedation in pediatric patients. Methods: With parental consent, 84 children who were placed under moderate or deep sedation with chloral hydrate for examinations from November 19, 2020 to July 9, 2022 were recruited. Results: Patients' average age was 19.9 months. Pediatric neurology patients and those who underwent electroencephalography took significantly longer to achieve sedation with chloral hydrate. There was a negative correlation between the time to achieve sedation and actual sleep time within 24 hours prior to the examination. Positive correlations were found between the actual sleep time 24 hoursprior to the examination and the second dose per weight, as well as between the sedation recovery time and awake hours before the examination. Conclusion: Sleep restriction is not an effective adjuvant therapy for chloral hydrate sedation in children, and sedation effects vary according to pediatric patients' characteristics. Therefore, it would be possible to reduce the unnecessary efforts of caregivers who restrict children's sleep for examinations. It is more important to educate parents about safe sedation than about sleep restriction.
COVID-19 팬데믹 기간 중 학령초기 자녀를 가진 여성의 스트레스 취약성, 부모소진이 정신건강에 미치는 영향: 영성의 매개효과
염미정(Yeom, Mijung),권민(Kwon, Min) 한국간호과학회 2024 Journal of Korean Academy of Nursing Vol.54 No.1
Purpose: This study examined the effects of stress vulnerability and parental burnout on the mental health of women with early school-aged children, with a focus on the mediating role of spirituality. Methods: A survey was conducted among 171 women with early school-aged children in Gyeonggi Province, Gangwon Province, and Seoul. Data were collected from September to December 2022 using the Korean-Symptom Check List 95, the Parental Burnout Assessment, and the Spirituality Assessment Scale. The data were analyzed using structural equation modeling with SPSS/WIN 22.0 and AMOS 20.0. Results: The study model demonstrated a good fit, explaining 40.5% of the variance in mental health through stress vulnerability, parental burnout, and spirituality. Spirituality had a significant direct impact on mental health. Additionally, participants’ spirituality directly influenced their mental health, while stress vulnerability and parental burnout indirectly affected their mental health and were mediated through spirituality. Conclusion: Stress vulnerability and parental burnout are negatively associated with mental health, while spirituality partially mediates these effects. Implementing a program to promote spirituality is suggested to assist mothers in recognizing the value and meaning of parenting activities during nursing interventions for mental health.