• 제목/요약/키워드: back stress

검색결과 612건 처리시간 0.032초

설문지를 이용한 피로 진단 지표 연구 (Indicator of Diagnosing Fatigue by Analyzing Questionnaire Data)

  • 윤탁현;박수정;최나래;김명;주종천;권영미
    • 대한한의진단학회지
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    • 제17권3호
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    • pp.179-188
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    • 2013
  • Objectives This study was designed to development the diagnosis indicators for the fatigue group without disease using analysis of questionnaire data. Methods The subjects were divided into three groups, the fatigue group with disease, the fatigue group without disease, non-fatigue group without disease. Thirteen kinds of questionnaire (Fatigue visual analogue scale, Fatigue severity scale, Pain visual analogue scale, Short-form McGill pain questionnaire score, Headache impact Test-6, Neck disability index, Oswestry low back pain disability questionnaire score, Blood stasis assessment scale, Physical activities questionnaire score, Beck depression inventory, Anger expression inventory score, Mood disability scale, Job stress scale) were carried out for the subjects. Results The results of this study are ; 1) The weight, the systolic and diastolic blood pressure were different among three groups. 2) Among nine questionnaires related to the physical or life conditions, the averages of eight questionnaires were not same one another. 3) Among four questionnaires related to the mental condition or autonomic nervous system, the averages of Beck depression inventory were not same one another. Conclusion The fatigue group without disease can be diagnosed through using the both the questionnaires related to the physical or life condition and the those related to the mental condition or autonomic nervous system.

허리굽힘과 다리자세가 작업지속시간에 미치는 영향에 관한 연구 (Effect of Trunk Flexion and Low Extremity Posture on Maximum Holding Time)

  • 이세정;장성록
    • 한국안전학회지
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    • 제26권3호
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    • pp.69-74
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    • 2011
  • Despite most of tasks in manufacturing, construction and agriculture, etc., were currently mechanized and automated, manual materials handling still existed in atypical working condition. In case of manual materials handling, repetitive work, inappropriate working posture, excessive force, contact stress might cause overload, which could lead to work-related musculoskeletal disorders and low back pains. On this basis, the goal of this study is to reveal the effects of various lifting postures of trunk angles and lower extremity postures on maximum holding time(MHT). Twenty two subjects were recruited from a university population. The experiment was designed by a combination of three trunk angle ($0^{\circ}$, $20^{\circ}$, $60^{\circ}$) and three lower extremity postures(straight, bent, kneeling). Before experimental trials, subjects performed MVC(maximum voluntary contraction) exertions in three trunk angles ($0^{\circ}$, $20^{\circ}$, $60^{\circ}$) to calculate 30%MVC at designated postures. In each trial, they were required to hold the handheld load(30%MVC) for a designated posture as long as they could. The results of MVC by trunk angles were measured in $0^{\circ}$ > $20^{\circ}$ > $60^{\circ}$ orders, but those of MHT measured in $20^{\circ}$ > $0^{\circ}$ > $60^{\circ}$ orders. These results showed that straight posture is the ideal working posture in work exerted a strong force for a short time, but the ability to work might be improved in the trunk angle $20^{\circ}$ in work required 30%MVC for a long time. Also, results of MVC and MHT by lower extremity postures measured in straight > bent > kneeling orders.

춤이 큰 웨브 변단면 H형 보의 휨내력에 대한 실험적 평가 (Experimental Evaluation of Flexural Performance Evaluation of Tapered H-Section Beams with Slender Web)

  • 심현주;이성희;김진호;이은택;최성모
    • 한국강구조학회 논문집
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    • 제19권5호
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    • pp.483-492
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    • 2007
  • 최근 대형 장스팬 규모에 많이 적용되는 PEB 시스템은 휨모멘트의 크기에 따라 부재형상을 최적화 한 변단면부재를 사용함으로써 경제적인 경쟁력을 갖는 구조시스템이다. 그러나 PEB 시스템의 관련기술은 대부분 외국에서 수입된 것으로 구조거동에 관한 연구 및 국내 설계규준이 미비하다. 특히 PEB 시스템에서의 변단면부재(래프터)들은 비조밀단면(noncompact section) 또는 세장단면(slender section)을 갖는 경우가 많으므로 좌굴에 대한 영향을 많이 받게 된다. 따라서 본 연구에서는 웨브의 판폭두께비, 스티프너 유무, 횡비지지길이 등을 변수로 하여 총 4개의 실대형 실험체를 제작 휨성능 실험을 수행하였다. 이에 대하여 세장한 웨브 변단면 부재의 구조 안정성을 실험적으로 평가하고 PEB 시스템의 설계를 위한 기초자료를 제공하고자 한다.

Numerical and experimental study of multi-bench retained excavations

  • Zheng, Gang;Nie, Dongqing;Diao, Yu;Liu, Jie;Cheng, Xuesong
    • Geomechanics and Engineering
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    • 제13권5호
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    • pp.715-742
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    • 2017
  • Earth berms are often left in place to support retaining walls or piles in order to eliminate horizontal struts in excavations of soft soil areas. However, if the excavation depth is relatively large, an earth berm-supported retaining system may not be applicable and could be replaced by a multi-bench retaining system. However, studies on multi-bench retaining systems are limited. The goal of this investigation is to study the deformation characteristics, internal forces and interaction mechanisms of the retaining structures in a multi-bench retaining system and the failure modes of this retaining system. Therefore, a series of model tests of a two-bench retaining system was designed and conducted, and corresponding finite difference simulations were developed to back-analyze the model tests and for further analysis. The tests and numerical results show that the distance between the two rows of retaining piles (bench width) and their embedded lengths can significantly influence the relative movement between the piles; this relative movement determines the horizontal stress distribution in the soil between the two rows of piles (i.e., the bench zone) and thus determines the bending moments in the retaining piles. As the bench width increases, the deformations and bending moments in the retaining piles decrease, while the excavation stability increases. If the second retaining piles are longer than a certain length, they will experience a larger bending moment than the first retaining piles and become the primary retaining structure. In addition, for varying bench widths, the slip surface formation differs, and the failure modes of two-bench retained excavations can be divided into three types: integrated failure, interactive failure and disconnected failure.

SM45C재의 PVD코팅과 필름에 의한 트라이볼러지 특성 (Variations in Tribological Characteristics of SM45C by PVD Coating and Thin Films)

  • 심현보;서창민;김종형;서민수
    • 한국해양공학회지
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    • 제32권6호
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    • pp.502-510
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    • 2018
  • In order to accumulate data to lower the friction coefficient of a press mold, tribological tests were performed before and after coating SM45C with a PVC/PO film and plasma coating (CrN, concept). The ultrasonic nanocrystal surface modification (UNSM)-treated material had a nano-size surface texture, high surface hardness, and large and deep compressive residual stress formation. Even when the load was doubled, the small amount of abrasion, small weight of the abrasion, and width and depth of the abrasion did not increase as much as those of untreated materials. A comparison of the weight change before and after the tribological test with the CrN and the concept coating material and that of the untreated material showed that the wear loss of the concept coating material and P-UNSM treated material (that is, the UNSM treated material treated with the concept coating) showed a tendency to decrease by approximately 55-75%. Concept 100N had a lower friction coefficient of about 0.6, and P-UNSM-30-100N showed almost the same curve as concept 100N and had a low coefficient of friction of about 0.6. The concept multilayer coating had a thickness of $5.32{\mu}m$. In the beginning, the coefficient of friction decreased because of the plasma coating, but it started to increase from about 250-300 s. After about 350 s, the coefficient of friction tended to approach the friction coefficient of the SM45C base metal. The SGV-280F film-attached test specimen was slightly pushed back and forth, but the SM45C base material was not exposed due to abrasion. The friction coefficient was 0.22, which was the lowest, and the tribological property was the best in this study.

한방여성의학에서 추나요법을 활용한 국내 연구 동향 분석 (A Review of the Domestic Study Trends on Obstetrics & Gynecological Diseases with Chuna Manual Therapy)

  • 이진욱;황영식;김규태;박승혁;이진무;이창훈;장준복;황덕상
    • 대한한방부인과학회지
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    • 제32권2호
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    • pp.87-99
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    • 2019
  • Objectives: The aim of this study was to analyse the domestic trends of Chuna manual therapy on Obstetrics and Gynecological Diseases in Korean literature. Methods: We searched for papers which had Chuna manual therapy through 2 related journals and 5 Korean web databases. All relevant papers were selected and extracted to be analyzed according to their study designs, academic journals, and target disease. Results: Nine papers belonged to four types of study designs, systematic review, randomized or non-randomized controlled trial and case report. And they were published in four kinds of academic journals. There were four papers about postpartum pain, two low back pain during pregnancy, and a stress urinary incontinence. The exact Chuna techniques were explained in only seven papers. All of papers have been shown that Chuna manual therapy is useful for obstetrics and gynecological diseases. Conclusions: It has been identified that Chuna manual therapy could be a good treatment for obstetrics and gynecological diseases. However, more clinical and well-designed studies with Chuna manual therapy will be needed.

조선 도학정치사(道學政治史)에서의 사암(思庵) 박순(朴淳)의 위상 - '세도(世道)'와 '청의(淸議)'를 중심으로 - (Status of Saam Park Sun in History of Joseon Dàoxué Politics - Focusing on 'shìdào' and 'qīngyì')

  • 최영성
    • 동양고전연구
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    • 제68호
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    • pp.319-344
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    • 2017
  • 사암 박순(1523~1589)은 16세기 도학정치사에서 매우 중요한 위치를 차지한다. 선조가 즉위한 뒤 14년간이나 재상을 지내면서, 그 이전의 훈척정치(勳戚政治)를 도학정치로 바꾸는 데 지도적 위치에 있었다. 그는 이전 시기의 정암(靜菴) 조광조(趙光祖: 1482~1519)가 부르짖은 도학정치의 이념을 계승하여 신진 사류(士類)에 의한 개혁정치를 추구하였다. 원칙과 여론이 일치되는 도학적 이상정치를 추구하였고, 이것의 실현을 위해 '세도(世道)'를 바로잡고 '청의(淸議)'를 신장하는 데 앞장섰다. 도학정치를 세도정치(世道政治)라고 하는 이유가 여기에 있다. 한편 그는 잘못된 현실을 비판하고 이상을 실현하는 준거(準據)로 '고례(古禮)'를 중시하였다. 그가 생각하는 '고'는 단순한 시간상의 되돌림이 아니었다. 이상이자 원리이며 전통이었다. 그는 '고'의 정신으로 돌아가는 것이야말로 가장 의미 있는 개혁이라고 생각하였다. 그가 국가의 전례(典禮)에서 '고례'의 실천을 강조하며 이것을 관철시키려고 애썼던 것은 이 때문이었다.

ERW 용접 전후 API X70 라인파이프강의 미세조직과 기계적 특성 변화 (Effect of Electrical Resistance Welding on Microstructure and Mechanical Properties of API X70 Linepipe Steel)

  • 오동규;최예원;신승혁;정한길;곽진섭;황병철
    • 열처리공학회지
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    • 제35권4호
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    • pp.185-192
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    • 2022
  • Variations in the microstructure and mechanical properties of API X70 steel processed by piping, electrical resistance welding (ERW), and post seam annealing (PSA) are investigated in this study. In the welding zone, some elongated pearlites are formed and grains coarsening occurs due to extra heat caused by the ERW and PSA processes. After the piping, the base metal shows continuous yielding behavior and a decrease in yield and impact strengths because mobile dislocation and back stress are introduced during the piping process. On the other hand, the ERW and PSA processes additionally decreased the impact strength of welding zone at room and low temperatures because some elongated pearlites easily act as crack initiation site and coarse ferrite grains facilitate crack propagation. As a result, the fracture surface of the welding zone specimen tested at low temperature revealed mostly cleavage fracture unlike the base metal specimen.

Epithelial to mesenchymal transition (EMT) of feto-maternal reproductive tissues generates inflammation: a detrimental factor for preterm birth

  • Menon, Ramkumar
    • BMB Reports
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    • 제55권8호
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    • pp.370-379
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    • 2022
  • Human pregnancy is a delicate and complex process where multiorgan interactions between two independent systems, the mother, and her fetus, maintain pregnancy. Intercellular interactions that can define homeostasis at the various cellular level between the two systems allow uninterrupted fetal growth and development until delivery. Interactions are needed for tissue remodeling during pregnancy at both fetal and maternal tissue layers. One of the mechanisms that help tissue remodeling is via cellular transitions where epithelial cells undergo a cyclic transition from epithelial to mesenchymal (EMT) and back from mesenchymal to epithelial (MET). Two major pregnancy-associated tissue systems that use EMT, and MET are the fetal membrane (amniochorion) amnion epithelial layer and cervical epithelial cells and will be reviewed here. EMT is often associated with localized inflammation, and it is a well-balanced process to facilitate tissue remodeling. Cyclic transition processes are important because a terminal state or the static state of EMT can cause accumulation of proinflammatory mesenchymal cells in the matrix regions of these tissues and increase localized inflammation that can cause tissue damage. Interactions that determine homeostasis are often controlled by both endocrine and paracrine mediators. Pregnancy maintenance hormone progesterone and its receptors are critical for maintaining the balance between EMT and MET. Increased intrauterine oxidative stress at term can force a static (terminal) EMT and increase inflammation that are physiologic processes that destabilize homeostasis that maintain pregnancy to promote labor and delivery of the fetus. However, conditions that can produce an untimely increase in EMT and inflammation can be pathologic. These tissue damages are often associated with adverse pregnancy complications such as preterm prelabor rupture of the membranes (pPROM) and spontaneous preterm birth (PTB). Therefore, an understanding of the biomolecular processes that maintain cyclic EMT-MET is critical to reducing the risk of pPROM and PTB. Extracellular vesicles (exosomes of 40-160 nm) that can carry various cargo are involved in cellular transitions as paracrine mediators. Exosomes can carry a variety of biomolecules as cargo. Studies specifically using exosomes from cells undergone EMT can carry a pro-inflammatory cargo and in a paracrine fashion can modify the neighboring tissue environment to cause enhancement of uterine inflammation.

피부(皮膚) 창상(創傷) 동물모델에서 흑삼(黑蔘) 열수 추출물 경구 투여의 효과 (Effects of Oral Administered Hot Water Extracts of Korean Black Ginseng on Wound Healing in Mice)

  • 김태령;김영준;우창훈
    • 한방재활의학과학회지
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    • 제32권1호
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    • pp.1-19
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    • 2022
  • Objectives This study aims to evaluate the wound healing effects of oral administered hot water extracts of Korean black ginseng (KBG). Methods 40 C57BL/6 mice were divided into five groups; normal, control, vitamin E 200 mg/kg, KBG 100 mg/kg, KBG 200 mg/kg, each n=8. Skin wounds were made in the back of all mice except normal group using biopsy punches. Wounds were observed on days 7 and 14 after injury. The anti-oxidant and inflammatory protein levels were evaluated using western blotting. Skin tissue was analyzed by hematoxylin & eosin and Masson's trichrome staining method. Results KBG significantly accelerated reducing wound area. KBG significantly decreased myeloperoxidase activity. KBG significantly decreased oxidative stress factors such as NADPH oxidase-4 and p22phox and increased antioxidant enzymes including nuclear factor erythroid 2-related factor2, kelch-like ECH-associated protein-1, heme oxygenase-1, superoxide dismutase, catalase and glutathione peroxidase-1/2. Moreover, KBG significantly decreased inflammation factors including nuclear factor-κB, phosphorylated inhibitor of κBα, cyclooxygenase-2, inducible nitric oxide synthase, tumor necrosis factor-α and interleukin (IL)-6 and increased anti-inflammation cytokine such as IL-4 and IL-10. In addition, KBG significantly increased tight junction proteins including claudin-1, claudin-3, claudin-4. In histopathologic, KBG made the epithelium thin and uniform, and accelerated the remodeling of collagen. Conclusions The results suggest that KBG has healing effects on skin wound in mice by anti-inflammatory and antioxidant activity.