• 제목/요약/키워드: Standard normal Distribution

검색결과 323건 처리시간 0.025초

Study of surgical anatomy of portal vein of liver segments by cast method and its clinical implications

  • Shrikantaiah, Vidya C.;Basappa, Manjaunatha;Hazrika, Sangita;Ravindranath, Roopa
    • Anatomy and Cell Biology
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    • 제51권4호
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    • pp.232-235
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    • 2018
  • Portal vein provides about three-fourths of liver's blood supply. Portal vein is formed behind the neck of pancreas, at the level of the second lumbar vertebra and formed from the convergence of superior mesenteric and splenic veins. The purpose of this study is to review the normal distribution and variation, morphometry of portal vein and its branches for their implication in liver surgery and preoperative portal vein embolization. It is also helpful for radiologists while performing radiological procedures. A total of fresh 40 livers with intact splenic and superior mesenteric vein were collected from the mortuary of Forensic Department, JSS Medical College and Mysuru Medical College. The silicone gel was injected into the portal vein and different segments were identified and portal vein variants were noted. The morphometry of portal vein was measured by using digital sliding calipers. The different types of portal vein segmental variants were observed. The present study showed predominant type I in 90% cases, type II 7.5% cases, and type III 2.5% cases. Mean and standard deviation (SD) of length of right portal vein among males and females were $2.096{\pm}0.602cm$ and $1.706{\pm}0.297cm$, respectively. Mean and SD of length of left portal vein among males and females were $3.450{\pm}0.661cm$ and $3.075{\pm}0.632cm$, respectively. The difference in the Mean among the males and females with respect to length of right portal vein and left portal vein was found to be statistically significant (P=0.010). Prior knowledge of variations regarding the formation, termination and tributaries of portal vein are very helpful and important for surgeons to perform liver surgeries like liver transplantation, segmentectomy and for Interventional Radiologists.

운전 중 고전력 케이블의 절연저항 데이터의 취득과 통계적 처리 방법 (Data Acquisition and Statistical Processing of Insulation Resistance for High-Power Cables in Operation)

  • 박성희;엄기홍
    • 한국인터넷방송통신학회논문지
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    • 제18권6호
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    • pp.181-186
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    • 2018
  • 산업화의 추세에 따라 수요가 급증하고 있는 고전력을 생산하기 위하여 시설장비 및 부하의 대용량화가 수반되고 있다. 전기설비의 규모는 점차 복잡해 지고, 대규모화 됨으로써 고도 정보화 사회로의 발전에 크게 기여하고 있다. 그러나, 발전 설비에서 불의의 사고가 발생하여 전기의 생산이 중단된다면, 전기에 의존하여 작동 중인 수 많은 장비가 지장을 받게되고, 산업사회에 막대한 경제적 손실 및 장애를 초래하게 된다. 사고가 발생한 발전설비를 복구하기 위해서는 많은 시간과 비용이 소요되어 국가 산업 활동에 막대한 경제적 피해를 끼치게 된다. 사고를 미연에 방지하기 위하여 케이블의 동작 상태를 정기적으로 감시 확인하여야 한다. 우리는 사고가 가장 빈번하게 발생하는 접속부에 대해 안정적인 사용을 위한 진단의 정확성과 신뢰성을 향상시키기 위한 연구를 하였다. 이 논문에서 데이터 취득을 하고, 통계적 처리를 하기 위한 방법을 제시한다.

건물 내 석면제거 작업과 공기 중 석면의 외부누출 위험성 평가 (A Risk Assessment of Asbestos Fiber Leaks to Environment during Asbestos Removal Activity in Buildings)

  • 백남원;이승철;변재철;이동희
    • 한국산업보건학회지
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    • 제30권4호
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    • pp.405-411
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    • 2020
  • Objectives: The objectives of this study were to investigate whether airborne fibers were released to the outside air from the asbestos removal area in buildings, and to confirm the existence of asbestos fibers in samples using transmission electron microscopy(TEM). Methods: A total of 1,295 samples was collected from inside and outside 155 asbestos removal areas. To investigate the release of asbestos fibers from the removal area, samples were collected at three locations, such as an entrance to change room, an exit of negative pressure unit(NPU) and perimeter areas. Samples were also collected in the removal area prior to and after removal activity. All samples were analyzed by phase contrast microscopy(PCM) and one-tenth of the samples was analyzed using TEM to discriminate asbestos fibers. Results: During the asbestos removal activity, 27(4.1%) of 662 samples collected outside the removal area showed airborne fiber concentrations equal to or in excess of 0.01 f/cc, the permissible emission standard of the Korean Ministry of Environment. Further, 111 samples were analyzed using TEM. The distribution of asbestos fiber concentrations was log-normal. It was found that 51 of 111 samples(46%) contained asbestos fibers. Conclusions: There is a potential risk of asbestos exposure among neighbors and the public outside the asbestos removal areas. It is recommended that the asbestos removal work be conducted strictly following the specifications required by government and/or professional organizations.

통계적 기법을 활용한 한국형 호우영향도 기준 산정 연구 (Statistical Techniques to Derive Heavy Rain Impact Level Criteria Suitable for Use in Korea)

  • 이승운;김병식;정승권
    • 대한토목학회논문집
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    • 제40권6호
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    • pp.563-569
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    • 2020
  • 기상현상 발생에 대한 기존 기상예보 방식에서 벗어나 기상재해가 사회와 인간생활에 끼치는 영향을 제공함으로써 사전에 영향범위에 대한 피해예방 및 행동예방을 취할 수 있는 영향예보를 제공하는 것이 필요하다. 이를 위해 미국, 영국, 프랑스 등 세계 각국에서는 호우, 폭설, 한파 등의 영향예보를 시행하고 있으며, 보다 효율적인 예보방안에 대해 고민하고 있다. 본 연구에서는 여러 기상현상 중 호우에 대한 영향예보를 국내의 실정에 맞도록 개선하고, 적용하기 위해 33개의 호우영향인자(Impact Library)를 격자단위(1 km)로 구축하고, 표준정규분포법을 이용하여 4개의 위험등급(Minimal, minor, significant, severe)의 기준을 산정하였다. 산정된 기준은 호우영향 대상체인 사람, 시설, 농업, 교통을 중심으로 한 6개의 카테고리(Residential, commercial, utility, community, agriculture, transport)에 대한 호우위험영향(Heavy rain risk impact)를 산정하기 위한 지표로 활용된다.

Evaluation of the accuracy of dental casts manufactured with 3D printing technique in the All-on-4 treatment concept

  • Hilin, Tas;Fatih, Demirci;Mesut, Tuzlali;Erkan, Bahce;Guler Yildirim, Avcu
    • The Journal of Advanced Prosthodontics
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    • 제14권6호
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    • pp.379-387
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    • 2022
  • PURPOSE. The aim of this study is to compare the casts obtained by using conventional techniques and liquid crystal display (LCD) three-dimensional (3D) print techniques in the All-on-4 treatment concept of the edentulous mandibular jaw. MATERIALS AND METHODS. In this study, a completely edentulous mandibular acrylic cast (typodont) with bone-level implants placed with the Allon-4 technique served as a reference cast. In this typodont, impressions were taken with the conventional technique and dental stone casts were obtained. In addition, after scanning the acrylic cast in a dental laboratory scanner and obtaining the Standard Tessellation Language (STL) data, 3D printed casts were manufactured with a 3D printing device based on the design. The stone and 3D printed casts were scanned in the laboratory scanner and STL data were obtained, and then the interimplant distances were measured using Geomagic Control X v2020 (3D Systems, Rock Hill, SC, USA) analysis software (n = 60). The obtained data were statistically evaluated with one-way analysis of variance (ANOVA) and Tukey's pairwise comparison tests. RESULTS. As a result of the one-way ANOVA test, it was determined that the stone casts, 3D printed casts, and reference cast values in all distance intervals conformed to the normal distribution and these values had a significant difference among them in all distance intervals. In Tukey pairwise comparison test, significant differences were found between casts at all distance intervals. In all analyses, the level of significance was determined as .05. CONCLUSION. 3D printed casts obtained with a 3D LCD printing device can be an alternative to stone casts when implants are placed in edentulous jaws. [J Adv Prosthodont 2022;14:379-87]

Accessory infraorbital foramen location using cone-beam computed tomography

  • Daesung An;Kumar K C;Chakorn Vorakulpipat;Supak Ngamsom;Thongnard Kumchai;Sunya Ruangsitt;Teeranut Chaiyasamut;Natthamet Wongsirichat
    • Journal of Dental Anesthesia and Pain Medicine
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    • 제23권5호
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    • pp.257-264
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    • 2023
  • Background: Accessory infraorbital foramen (AIOF) can change the normal course of emerging branches of the infraorbital nerve and blood vessels exiting the infraorbital foramen (IOF). This study aimed to examine the AIOF, number of foramina, and their position in relation to IOF using cone-beam computed tomography (CBCT). Methods: We performed a retrospective CBCT assessment of hospital records between January 2018 and August 2022. The CBCT of 507 patients were examined to extract information on the prevalence, number, position, linear distance from the IOF, and diameter of AIOF in relation to demographic factors. Descriptive statistics were used to evaluate the prevalence of AIOF. Mean and standard deviation were used to calculate the linear distance and diameter of the AIOF, respectively. The AIOFs, its distribution, and number were compared between sexes and sides using the chi-square test. The independent t-test and Mann-Mann-Whitney test were used to compare the mean difference between the sexes and sides. Statistical significance was set at P < 0.05. Results: In this current study, the prevalence of AIOF was 7.1% (36 of the 507 patients). Additionally, the current study examined the number of foramina using a single foramen on each side and double foramina located bilaterally at a distance from the AIOF to the IOF. The mean AIOF diameter was also studied, and the AIOF position with respect to the IOF on CBCT was superomedial or inferomedial. There were no statistically significant associations between any of the parameters assessed in this study when comparing sex and sides. Conclusions: A greater number of patients with AIOF presented with a single foramen and unilateral occurrence, without a statistically significant difference. The AIOF was most commonly located superomedial to the IOF.

일부 청소년의 체중조절과 관련된 요인에 관한 연구 -자아존중감, 신체만족도 및 중요도, 신체적 특성과 체형에 대한 인식을 중심으로- (The Factors Associated with Weight Control Experiences among Adolescents - Based on Self-esteem, Body-cathexis, Attitudes toward the Body, Anthropometric Characteristics and Perceptions of Body Shape -)

  • 허은실;강현진;이경혜
    • 대한지역사회영양학회지
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    • 제8권5호
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    • pp.658-666
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    • 2003
  • This study was carried out to investigate among adolescents (total=729) the relationship between their self-esteem, body-cathexis, their attitudes toward the importance of their bodies, their anthropometric characteristics, their perceptions of their body shapes and their experiences with weight control. The results are summarized as follows: The mean values for self-esteem and body-cathexis were generally low, but these values were significantly higher among boys than girls (p<0.01-0.001). However the mean values for their attitudes toward the importance of their bodies were relatively high and were significantly higher among girls than boys (p<0.01). The mean values for Percent Ideal Body Weight (PIBW) and Body Mass Index (BMI) were normal and no significant differences between the genders were observed. The distribution of the PIBW and the BMI values showed a higher rate for normal weights among the girls and a higher rate for underweightedness and obesity among the boys (p<0.01). With regard to their perception of their body image, among the boys, their current figures were almost identical with their idea of an ideal figure, but among the girls, their idea of an ideal figure was thinner than their current figure. The girls were more dissatisfied with their own body image than the boys (p<0.001). Fifty-four percent of the subjects had previous weight control experience, and the girls had significantly more experience than the boys (p<0.001). Their main reason for practising weight control was to lose weight (65.3%) Those who had more weight control experience had lower satisfaction with their body shapes, higher PIBW, higher BMIs or currently had fatter figures. Their standard image of their figures was influenced by TV (40.3%) and friends (36.9%). There was a weakly positive correlation between their self-esteem and their satisfaction with their body shapes, and a weakly negative correlation between their satisfaction with their body shapes and their attitudes toward the importance of their bodies. These results suggest the necessity for an educational program for adolescents as to foster a positive body image. Such a program should consider psychological factors such as self-esteem, satisfaction with body shape and attitudes toward the importance of the body.

초등학생 가정을 대상으로 한 바이오에어로졸 노출과 아토피와의 연관성 평가 (Evaluation of Atopy and Its Possible Association with Indoor Bioaerosol Concentrations and Other Factors at the Residence of Children)

  • 하진실;정혜정;변혜정;윤충식;김양호;오인보;이지호;하권철
    • 한국환경보건학회지
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    • 제37권6호
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    • pp.406-417
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    • 2011
  • Objectives: Exposure to bioaerosols in the indoor environment could be associated with a variety adverse health effects, including allergic disease such atopy. The objectives of this study were to assess children's exposure to bioaerosol in home indoor environments and to evaluate the association between atopy and bioaerosol, environmental, and social factors in Ulsan, Korea. Methods: Samples of viable airborne bacteria and fungi were collected by impaction onto agar plates using a Quick Take TM 30 and were counted as colony forming units per cubic meter of air (CFU/$m^3$). Bioaerosols were identified using standard microbial techniques by differential stains and/or microscopy. The environmental factors and possible causes of atopy based on ISAAC (International Study of Allergy and Asthma in Childhood) were collected by questionnaire. Results: The bioaerosol concentrations in indoor environments showed log-normal distribution (p < 0.01). Geometric mean (GM) and geometric standard deviation (GSD) of airborne bacteria and fungi in homes were 189.0 (2.5), 346.1(2.0) CFU/$m^3$, respectively. Indoor fungal levels were significantly higher than those of bacteria (p < 0.001). The concentration of airborne bacteria exceeded the limit recommended by the Korean Ministry of Environment, 800 CFU/$m^3$, in three out of 92 samples (3.3%) from 52 homes. The means of indoor to outdoor ratio (I/O) for airborne bacteria and fungi were 8.15 and 1.13, respectively. The source of airborne bacteria was not outdoors but indoors. GM of airborne bacteria and fungi were 217.6, 291.8 CFU/$m^3$ in the case's home and 162.0, 415.2 CFU/$m^3$ in the control's home respectively. The difference in fungal distributions between case and control were significant (p = 0.004) and the odds ratio was 0.996 (p = 0.027). Atopy was significantly associated with type of house (odds ratio = 1.723, p = 0.047) and income (odds ratio = 1.891, p = 0.041). Some of the potential allergic fungal genera isolated in homes were Cladosporium spp., Botrytis spp., Aspergillus spp., Penicillium spp., and Alternatia spp. Conclusions: These results suggest that there this should be either 'was little' meaning 'basically no significant association was found' or 'was a small negative' mean that an association was found but it was minor. It's a very improtant distinction. Association between airborne fungal concentrations and atopy and certain socioeconomic factors may affect the prevalence of childhood atopy.

평균-VaR 기준과 최적 포트폴리오 선택 (The Mean-VaR Framework and the Optimal Portfolio Choice)

  • 구본일;엄영호;추연욱
    • 재무관리연구
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    • 제26권1호
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    • pp.165-188
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    • 2009
  • 본 연구는 개별 자산의 수익률 분포에 대한 가정 없이 평균-VaR 기준에서의 프론티어 포트폴리오를 구하고, 수익률 분포의 고차 적률에 대한 투자자의 선호가 반영된 최적 포트폴리오를 선택하는 방법을 제시하였다. 프론티어 포트폴리오를 구하기 위해 수익률 분포에 대한 가정이 필요하지 않은 그리드와 랭크 방법을 제시하였고 최적 포트폴리오를 선택하기 위해 수익률 분포의 4차 적률까지 고려된 효용함수를 사용하였다. 제시한 방법론을 실제 자료에 적용해 보기위해 모건 스탠리에서 제공하는 선진국 지수, 개발도상국 지수, KOSPI 지수의 주별 수익률 자료를 사용하였다. 평균-VaR 기준과 평균-분산 기준에서의 프론티어 포트폴리오를 구하고 각 기준에서의 최적 포트폴리오를 선택해 서로 비교하였다. 표준편차의 차이뿐만 아니라 효용함수의 수준과 주별 기대수익률로 표현되는 확실성 등가의 차이를 살펴봄으로써 두 기준 간의 경제적 의미 차이에 대해서도 살펴보았다. 또한 부트스트래핑을 이용한 역사적 시뮬레이션의 방법을 사용해 두 기준 간 발생한 차이가 통계적으로 유의한 지를 본 연구에서 적용한 자료에서는 평균-VaR 기준의 투자자가 평균-분산 기준의 투자자에 비해 더 큰 표준편차를 지닌 최적 포트폴리오를 선택하고 위험 회피도가 큰 투자자일수록 평균-VaR 기준에서의 효용이 크고 확실성 등가도 더 크게 나타나는 경향이 나타났다. 그러나 두 기준 간 발생한 차이가 통계적으로 유의하지 않게 나타나 표준편차의 차이와 경제적인 의미 차이가 크지 않다는 사실을 확인하였다.

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PCITS에 의해 소손된 강이음쇠형 CSST의 특성 해석에 관한 연구 (A Study on the Properties Analysis of an Iron Fittings Type CSST Damaged by the PCITS)

  • 이장우;최충석
    • 한국화재소방학회논문지
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    • 제30권4호
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    • pp.121-127
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    • 2016
  • 본 논문에서는 대전류공급장치(PCITS)에 의해 소손된 강이음쇠형(iron fittings type) 금속플렉시블호스(CSST)의 구조 및 전기적 특성을 해석하였다. CSST는 보호 피막, 튜브, 너트, 클램프 링, 플레어 캡, 소켓, 볼 밸브 등으로 구성되어 있다. CSST의 내전압 평가는 전기 충전부와 비충전부 사이에 교류 전압 220 V를 1분간 인가하여 견뎌야 한다. 직류 500 V에 의한 절연 성능의 평가는 온도 상승 시험 전에 $1M{\Omega}$ 이상, 시험이 끝난 후에는 $0.3M{\Omega}$ 이상을 요구한다. 정상 제품의 평균 저항은 $11.5m{\Omega}$이었으나 PCITS로 130 A를 흘려 소손된 제품의 평균 저항 $11.50m{\Omega}$이었다. 또한 130 A가 약 10 s 흘렀을 때 튜브의 보호 피막이 일부 용융되었고, 검정색의 연기가 발생하였다. 60 s 경과되면 튜브의 대부분이 적색으로 발열되며, 전류가 120 s 흘렀을 때는 적열 범위가 넓어졌다. 95%의 신뢰 구간(CI)의 검증에서 P 값은 0.019로 정규 분포를 갖지 못하였으나 Anderson-Darling (AD) 통계량은 0.896, 표준 편차는 0.5573 등으로 양호한 특성을 나타냈다.