• 제목/요약/키워드: Stress-Timing

검색결과 68건 처리시간 0.026초

조기성조숙의 관련 인자 연구 (A study of factors influencing precocious puberty)

  • 김미화;이성국
    • 한국산학기술학회논문지
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    • 제13권7호
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    • pp.3123-3131
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    • 2012
  • 본 연구자는 만8세 미만의 초등학교 여아들의 조기성조숙 현황을 조사하고 조기성조숙에 영향을 미치는 인자에 대해서 연구하고자 하였다. 고령군에 소재한 초등학교 G, D 2개의 초등학교 1,2,3학년 여학생을 전수 253명을 대상으로 학부모의 동의를 얻어 성 발달정도 및 비만의 정도, 생활습관(운동습관, 식습관, 수면습관 등), 가정환경 등을 조사하여 조기성조숙 발현의 영향인자를 통계학적으로 분석하였다. 총 253명의 학생을 대상으로 조사하였으며 각 연령에서 성조숙 현상을 보인 여아는 6세 90명중 에서 7명(7.8%), 7세 68명 중에서 9명(13.2%), 8세 95명 중 50명(52.6%)으로 나타났고 전체 253명중 66명(26.1%)이였다. 조기성조숙에 영향을 미치는 인자로 통계적으로 유의성이 나타난 것은 비만도, 인스턴트섭취빈도, TV시청시간, 스트레스, 가족형태(결손가정)이었다. 비만도가 높을수록, 인스턴트 섭취 빈도가 높을수록, 스트레스가 많을수록, 결손가정에서 성 발달이 빨랐다. 본 연구의 결과 만8세 미만의 초등학교 저학년 여아 중 26.1%가 조기성조숙으로 나타났으며, 조기성조숙의 발현에 영향을 미치는 인자는 비만도, 인스턴트섭취 빈도, 스트레스, 가족형태(결손가정)등으로 조사 되었다.

노후콘크리트포장 원위치 파쇄기층(Rubblized-PCC)의 반사균열 억제를 위한 적정 파쇄 깊이 산정 (Estimation for optimum crush depth to prevent reflection crack for Rubblized-PCC in PCC pavements)

  • 이승우;전상민
    • 한국도로학회논문집
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    • 제6권4호
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    • pp.101-108
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    • 2004
  • 노후콘크리트 포장 수명을 연장하기 위한 방안으로 아스팔트 덧씌우기가 일반적이나 반사균열을 억제하기 어렵다는 단점이 있다. 반사균열을 억제하기 위하여 줄눈부 보수, 응력 완화층 설치가 적용되는 경우가 있으나 반사균열의 진전 속도를 늦추는 제한적인 성공을 보여 왔다. 콘크리트포장 슬래브를 원위치에서 파쇄하여 기층재료로 활용하고 그 위에 덧씌우기 포장을 건설하는 러블라이제이션 공법은 기존 덧씌우기 보강 공법을 갖고 있는 반사균열 문제를 완벽하게 해결할 수 있는 장점을 가지고 있다. 러벌라이제이션 공법을 적용할 경우 파쇄된 노후 콘크리트 포장층 상부층은 40mm-70mm로 파쇄되나 하부층은 100mm이상 되는 경우가 일반적이다. 국내 고속도로와 같이 상대적으로 두꺼운 콘크리트 포장 슬래브를 사용하는 경우 전체 포장 두께를 파쇄하기에 어려움이 있다. 따라서 파쇄된 노후 콘크리트 포장층이 반사균열을 유발시키지 않는 도로기층으로써의 역활을 확보하기 위한 적정 파쇄 깊이를 파악하기 위하여 본 연구에서는 미국 DOT에서 제안한 일반적인 파쇄규격(40mm-70mm)을 기준으로 파쇄 깊이를 0cm, 10cm, 20cm,로 변화시켜가며 반사균열 실내 모사 실험을 수행하여 반사균열 저항 특성을 분석하고 적정파쇄 깊이를 검토하였다.

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An enhanced root system developmental responses under drought by inoculation of rhizobacteria (Streptomyces mutabilis) contributed to the improvement of dry matter production in rice

  • Suralta, Roel R.;Cruz, Jayvee A.;Cabral, Maria Corazon J.;Niones, Jonathan M.;Yamauchi, Akira
    • 한국작물학회:학술대회논문집
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    • 한국작물학회 2017년도 9th Asian Crop Science Association conference
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    • pp.231-231
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    • 2017
  • Drought limits rice production under upland condition. This study quantified the effect of rhizobacteria inoculation on rice root system developmental response to drought and its role in maintaining high soil water use, and dry matter production under drought using NSIC Rc192 (rainfed lowland rice variety). The source of inoculant was Streptomyces mutabilis, a recently isolated rhizobacteria containing plant growth promoting compounds such as ACC deaminase, indole-3-acetic acid and phosphatase (Cruz et al., 2014, 2015). In the first experiment, pre-germination inoculation of seeds with S. mutabilis significantly increased the shoot and root (radicle) length as well as root hair lengths, relative to the non-inoculated control. In the second experiment, rice plants inoculated with S. mutabilis and grown in rootbox with soil generally had greater total root length under drought regardless of the timing of inoculations, relative to the non-inoculated control. Consequently, improved root system development contributed to the increase in soil water uptake under drought and thus, dry matter production. Among inoculation treatments, one-time inoculation of S. mutabilis either at pre-germination or pre-drought stress at 14 days after sowing (DAS), had significantly greater shoot dry matter production than three-time inoculation at pre-germination, at thinning (3 DAS) and at pre-drought (14 DAS). This study demonstrated the effectiveness of rhizobacteria (S. mutabilis) containing growth promoting compounds for enhancing drought dehydration avoidance root traits and improving the growth of rice plants under drought condition.

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Meta-synthesis Exploring Barriers to Health Seeking Behaviour among Malaysian Breast Cancer Patients

  • Yu, Foo Qing;Murugiah, Muthu Kumar;Khan, Amer Hayat;Mehmood, Tahir
    • Asian Pacific Journal of Cancer Prevention
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    • 제16권1호
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    • pp.145-152
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    • 2015
  • Barriers to health seeking constitute a challenging issue in the treatment of breast cancer. The current meta-synthesis aimed to explore common barriers to health seeking among Malaysian breast cancer patients. From the systematic search, nine studies were found meeting the inclusion criteria. Data extraction revealed that health behavior towards breast cancer among Malaysia women was influenced by knowledge, psychological, sociocultural and medical system factors. In terms of knowledge, most of the Malaysian patients were observed to have cursory information and the reliance on the information provided by media was limiting. Among psychological factors, stress and sense of denial were some of the common factors leading to delay in treatment seeking. Family member's advice, cultural beliefs towards traditional care were some of the common sociocultural factors hindering immediate access to advanced medical diagnosis and care. Lastly, the delay in referral was one of the most common health system-related problems highlighted in most of the studies. In conclusion, there is an immediate need to improve the knowledge and understanding of Malaysian women towards breast cancer. Mass media should liaise with the cancer specialists to disseminate accurate and up-to-date information for the readers and audience, helping in modification of cultural beliefs that hinder timing health seeking. However, such intervention will not improve or rectify the health system related barriers to treatment seeking. Therefore, there is an immediate need for resource adjustment and training programs among health professional to improve their competency and professionalism required to develop an efficient health system.

한국 청소년의 음주행동 잠재계층 유형 및 예측요인: 잠재계층분석 방법의 적용 (Patterns of Drinking Behaviors and Predictors of Class Membership among Adolescents in the Republic of Korea: A Latent Class Analysis)

  • 이해인;박선희
    • 대한간호학회지
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    • 제49권6호
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    • pp.701-712
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    • 2019
  • Purpose: Despite the high drinking rates and the complexity of drinking behaviors in adolescents, insufficient attention has been paid to their drinking patterns. Therefore, we aimed to identify patterns of adolescent drinking behaviors and factors predicting the distinct subgroups of adolescent drinking behaviors. Methods: We analyzed nationally representative secondary data obtained in 2017. Our final sample included 24,417 Korean adolescents who had consumed at least one glass of alcohol in their lifetime. To investigate patterns of drinking behaviors, we conducted a latent class analysis using nine alcohol-related characteristics, including alcohol consumption levels, solitary drinking, timing of drinking initiation, and negative consequences of drinking. Furthermore, we investigated differences in demographics, mental health status, and characteristics of substance use across the latent classes identified in our study. To do so, we used the PROC LCA with COVARIATES statement in the SAS software. Results: We identified three latent classes of drinking behaviors: current non-drinkers (CND), binge drinkers (BD), and problem drinkers (PD). Compared to the CND class, both BD and PD classes were strongly associated with higher academic year, lower academic performance, higher levels of stress, suicidal ideation, lifetime conventional or electronic cigarette use, and lifetime use of other drugs. Conclusion: Health professionals should develop and implement intervention strategies targeting individual subgroups of drinking behaviors to obtain better outcomes. In particular, health professionals should consider different characteristics across subgroups of adolescent drinking behaviors when developing the interventions, such as poor mental health status and other substance use among binge and problem drinkers.

해양환경의 변동성을 고려한 해상풍력터빈 지지구조물의 기대수명 평가 (Expected Life Evaluation of Offshore Wind Turbine Support Structure under Variable Ocean Environment)

  • 이기남;김동현;김영진
    • 한국해양공학회지
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    • 제33권5호
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    • pp.435-446
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    • 2019
  • Because offshore structures are affected by various environmental loads, the risk of damage is high. As a result of ever-changing ocean environmental loads, damage to offshore structures is expected to differ from year to year. However, in previous studies, it was assumed that a relatively short period of load acts repeatedly during the design life of a structure. In this study, the residual life of an offshore wind turbine support structure was evaluated in consideration of the timing uncertainty of the ocean environmental load. Sampling points for the wind velocity, wave height, and wave period were generated using a central composites design, and a transfer function was constructed from the numerical analysis results. A simulation was performed using the joint probability model of ocean environmental loads. The stress time history was calculated by entering the load samples generated by the simulation into the transfer function. The damage to the structure was calculated using the rain-flow counting method, Goodman equation, Miner's rule, and S-N curve. The results confirmed that the wind speed generated at a specific time could not represent the wind speed that could occur during the design life of the structure.

구순열과 구개열의 발생요인 및 치료 경향 (RECENT TRENDS IN INCIDENCE AND MANAGEMENT OF CLEFT LIP AND PALATE)

  • 윤천주;유선열
    • Maxillofacial Plastic and Reconstructive Surgery
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    • 제28권4호
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    • pp.295-309
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    • 2006
  • The present study was aimed to evaluate the incidence, etiological factors, and management of cleft lip and palate. Two hundred and twenty patients with cleft lip and/or cleft palate who were treated at Department of Oral and Maxillofacial Surgery, Chonnam National University Hospital, during the period between January 1994 and December 2003 were reviewed. The ratios of cleft lip : cleft lip with cleft palate : and cleft palate were 0.4:1.1:1. Males were more common than females in cleft lip (1.3:1) and cleft lip and palate (2.5:1), while females were more common than males in cleft palate (1:1.3). In the cleft side, left clefts were more prevalent than right clefts (cleft lip 1.3:1, cleft lip and palate 1.6:1). Unilateral clefts were more common than bilateral clefts in cleft lip (79:21). Cleft lip and cleft palate were more common in those with blood type A (34.5%) than those with other types. There was no significant relationship between birth season and frequency of clefts. The clefts were common in the first-born (48.8%), and in mothers aged between 25 and 29 (51.7%). Medication (24.7%) and stress (16.7%) during the first trimester were noted. Positive familial history was noted in 13 cases (5.9%). Thirty-two cases (15%) were associated with other congenital anomalies, in which tonguetie (40.6%) and congenital heart disease (21.9%) were most common. Among 100 patients with cleft palate, 77 patients had middle ear disease (77%), which occurred predominently in the incomplete cleft palate. Seventy-six among the 77 patients received myringotomy and ventilation tube insertion, and the remaining one received antibiotic medication only. Cleft lips were treated primarily at 3 to 6 months, and cleft palates were at 1 to 2 years. Treatment regimens included modified Millard method mainly in the cleft lip, and Wardill V-Y, Dorrance method, and Furlow method in the cleft palate. The percentage of palatal lengthening as type of cleft palate was greater in the incomplete cleft palate group (11.2%) than in the complete cleft palate group (9.6%). The percentage of palatal lengthening as operating method was no difference between the Furlow method (10.9%) and the push back method (10.7%). As postoperative complications, hypertrophic scar was most frequent in the cleft lip, and oronasal fistula in the cleft palate. In summary, it was shown that medication and stress during the first trimester of pregnancy were frequently associated with cleft lip and cleft palate, adequate timing and selection of method of operation are important factors to obtain morphologically and functionally good results. Furthermore prevention and treatment of middle ear disease are important in cleft palate patients because of its high co-occurrence.

정현파형 주름강판의 전단좌굴특성 분석 (An Investigation of the Shear Buckling Characteristics of Sinusoidal Corrugated Steel Plates)

  • 손수덕;유미나;이승재;강주원
    • 한국구조물진단유지관리공학회 논문집
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    • 제18권3호
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    • pp.10-19
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    • 2014
  • 파형강판은 제형, 정현형 등의 형상으로 얇은 강판을 주름지게 가공한 것으로 두꺼운 평판을 대신하여 사용하여도 높은 면외방향의 강성을 확보할 수 있다. 또한, 아코디언효과로 축방향 강성이 거의 없어 플레이트거더의 웨브에 적용할 경우 웨브가 전단력만을 부담하는 방법으로 쉽게 설계할 수 있다. 그러나 파형강판의 전단좌굴은 평판과는 달리 국부좌굴과 전체좌굴 외에도 이들의 연성에 의해서도 좌굴이 발생하는 매우 복잡한 특성이 있으며, 이러한 연성좌굴에 대한 원인과 특성의 규명은 정현형의 경우 제형보다 연구결과가 부족한 실정이다. 따라서 본 연구에서는 정현형 파형강판의 전단좌굴 특성과 연성좌굴이 발생하는 경향에 대해서 연구하였다. 전단좌굴강도를 계산하기 위해서는 유한요소프로그램을 이용하였고 해석결과를 정해와 비교하였다. 또한, 주름의 두께와 형상 파라메타에 따른 좌굴응력 변화의 특성과 좌굴모드형상의 변화를 분석하였으며, 이들의 결과를 이론식의 결과와 비교하여 좌굴양상의 변화시점에 대해서 분석하였다.

Effect of Reverse Feeding on the Reproductive System in Male Rats

  • Jeon, Eun-Young;Lee, Sung-Ho
    • 한국발생생물학회지:발생과생식
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    • 제16권3호
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    • pp.227-233
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    • 2012
  • Circadian timing system plays a major role in a wide range of reproductive function. However it is plausible idea that other environmental and/or internal cue might be simultaneously participated in the optimal regulation of reproductive system. In the present study we extended the reverse feeding (RF) time regimen up to 8 weeks, then measured the general and reproductive indices of the animals. The animals of ad libitum feeding group (Control, CON) have free access to food for 4, 6 and 8 weeks, respectively. The day feeding animals (reverse feeding, RF group) have restricted access to food during daytime (09:00-18:00) for 4, 6 and 8 weeks, respectively. When the feeding schedules were over, key indices were measured. After 4 weeks and 8 weeks of feeding, body weights of animals were not significantly different. However, body weights of 6 weeks RF animals were significantly smaller than those of control animals (CON : RF = $333.46{\pm}12.71$ g : $289.91{\pm}8.31$ g, p<0.01). The blood glucose levels of 4 weeks RF animals were significantly decreased compared to the levels of control animals (CON : RF = $161.4{\pm}2.7$ mg/dL : $176.7{\pm}5$ mg/dL, p<0.01) while the levels of 6 weeks RF and 8 weeks RF animals were not different form those of control animals. Reproductive and non-reproductive tissue weights from 6 weeks RF group were significantly lowered than those from CON group (testis, CON : RF = $1.4714{\pm}0.0174$ g : $1.3724{\pm}0.0168$ g, p<0.001; epididymis, CON : RF = $0.3574{\pm}0.0059$ g : $0.3243{\pm}0.0068$ g, p<0.001; seminal vesicle, CON : RF = $0.1655{\pm}0.0068$ g : $0.1328{\pm}0.0054$ g, p<0.001; prostate, CON : RF = $0.3350{\pm}0.0231$ g : $0.2528{\pm}0.0143$ g, p<0.01). After 4 weeks and 8 weeks of reverse feeding, sperm counts in RF animals were markedly reduced than those in control animals[CON 4W : RF 4W = $121.17{\pm}9.96\;({\times}10^6)$ : $50.86{\pm}9\;({\times}10^6)$, p<0.001; CON 8W : RF 8W= $138.69{\pm}9.8\;({\times}10^6)$ : $108.94{\pm}4.22\;({\times}10^6)$, p<0.001]. Present study indicates that RF may induce an adaptable metabolic stress and cause impairment of androgen-dependent reproductive tissues. On-going longitudinal studies will allow a better understanding of the how does mealtime shift affect the reproductive function and exact nature of adaptation.

30mm 자동포용 폐쇄기의 내구성 향상에 관한 연구 (A Study on Durability Improvement of Breech Block for 30mm Automatic Gun)

  • 박영민;김성훈;노상완;김성진
    • 한국산학기술학회논문지
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    • 제21권5호
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    • pp.47-53
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    • 2020
  • 본 연구는 30mm 자동포에 적용 중인 폐쇄기의 내구성을 향상시킴으로서 제품의 신뢰성을 증가시키는 것을 목적으로 하고 있다. 연구 대상인 폐쇄기는 왕복운동을 통해 탄의 장전, 약실 폐쇄, 탄피 추출 등의 기능을 하는 포의 주요 구성품으로 높은 신뢰성이 요구되지만 운용 중 폐쇄기 균열이 조기에 발생됨에 따라 개선이 필요하였다. 개선을 위해 원인 분석을 수행하여 균열은 반복적인 충격에 의해 발생함을 확인하였다. 그러하여 다음과 같은 개선방안을 연구하고 입증 사격을 통해 효과를 증명하였다. 개선방안으로 소재 변경으로 충격 흡수에너지를 증가시켰으며 균열 부위의 R 값을 증대하여 응력 집중을 완화하였다. 또한, 쇼트피닝 추가, 크롬도금 삭제, 단조 방법 변경으로 피로수명을 증가시켰다. 개선품의 입증 사격 결과 5,000발까지 사격 장애가 발생하지 않았고 균열의 시작이 늦춰졌으며 그 깊이가 작아졌다. 따라서 개선방안이 적용된 폐쇄기는 기존 제품 보다 내구성이 향상됨을 확인하였다. 본 연구는 유사제품의 내구성 향상, 폐쇄기 균열 성장 속도 예측(수명 연구) 및 균열 허용 기준 설정을 추진할 때 유용한 참고 자료로 활용될 수 있을 것으로 기대된다.