• 동력기계공학회지
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• 제10권4호
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• pp.119-126
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• 2006

Gerotor hydraulic motor is widely used in hydraulic systems due to its low speed, high torque output and compactness in rotational direct driving of a heavy weight. Gerotor is a Planar mechanism consisted of a pair of rotor and circular teeth of stator assembly which forms a closed space, so called a chamber. The motion of rotor relative to the circular tooth is produced by the pressure difference of hydraulic operating fluid between the adjacent chamber. As all active contact points of rotor and circular teeth are subjected to very high sliding friction, a reduction in the performance of the gerotor hydraulic motor can not be avoided. Therefore, the core design parameters of gerotor profile used in hydraulic motors is to minimize a friction force by high contact stresses. The analytical design method of gerotor profile, based on envelope of a family of curves, is proposed. In this study, the influence of the tip clearances on three critical contact points between rotor and circular teeth of stator assembly has been explored by experimental data in this paper. At the same time a improvement method to reduce the friction force is proposed and the tip clearances on three critical points for getting an optimum gerotor profile are also analyzed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.831-837
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• 2005

In this study, a computer program to predict the behavior of laterally loaded single pile and pile groups was developed by using a beam-column analysis in which the soils are modeled as nonlinear springs by a family of p-y curves for subgrade modulus. The special attention was given to the lateral displacement of a single pile and pile groups due to the soil condition and the cap rigidity. The analysis considering group effect was carried out for $2\;{\times}\;2\;and\;3\;{\times}\;3$ pile groups with the pile spacing 3.0B, 4.0B and 5.0B. Based on the results obtained, it is found that the overall distributions of deflection, slope, moment, and shear force in a single pile give a reasonable results irrespective of cap connectivity conditions. It is also found that even though there are some deviations in deflection prediction compared with the observed ones, the prediction by present analysis simulates much better the general trend observed by the centrifuge tests than the numerical solution predicted by PIGLET.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.369-378
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• 2010

In this study, a computer program to predict the behavior of laterally loaded single pile and pile groups was developed by using a beam-column analysis in which the soils are modeled as nonlinear springs by a family of p-y curves for subgrade modulus. The special attention was given to the lateral displacement of a single pile and pile groups due to the soil condition and the cap rigidity. The analysis considering group effect was carried out for $2{\times}2$ and $3{\times}3$ pile groups with the pile spacing 3.0B, 4.0B and 5.0B. Based on the results obtained, it is found that the overall distributions of deflection, slope, moment, and shear force in a single pile give a reasonable results irrespective of cap connectivity conditions. It is also found that even though there are some deviations in deflection prediction compared with the observed ones, the prediction by present analysis simulates much better the general trend observed by the centrifuge tests than the numerical solution predicted by PIGLET.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1243-1248
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• 2010

Fatigue design and evaluation of welded joints are typically carried out by weld classification approach in which a family (theoretically infinite) of parallel nominal stress based S-N curves are used according to joint types and loading modes as well as extrapolation-based hot spot stress. Traditional finite element methods are not capable of consistently capturing the stress concentration effects on fatigue behavior due to their mesh-sensitivity in stress determination at welds resulted from notch stress singularity. The extrapolated hot spot stresses tend vary, depending on the element sizes, types, joint types, and loading mode. however, the equilibrium-equivalent structural stress method(E2S2) has been recently developed through several joint industry projects as a robust method to analyze welded components using finite element analysis. This method has been proven effective in correlating a large amount of published fatigue test results in the literature such as master S-N curve and has used for evaluating the fatigue life of welding components. In this study, fatigue analysis of the welding bogie frame is examined using E2S2 method with master S-N curve.

• Journal of Preventive Medicine and Public Health
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• 제37권1호
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• pp.51-58
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• 2004

Objectives : The purpose of this study was to estimate the prevalence of metabolic syndrome, as defined by the ATP III report, in some Korean adults and use the Asian-Pacific proposed waist circumference to investigate waist circumference in some Korean adults using ROC curves. Methods : Study subjects were seventy-five thousands and ninety one persons(47,979 men and 27,111 women) who were selected among the patients who visited hospital for health evaluation from January 2000 to December 2001. All subjects were measured by height, weight, waist and hip circumferences, blood pressure and blood chemistry(lipid profile). Results : The mean age was $41.6{\pm}8.5$ years in men, $41.1{\pm}10.4$ years in women(p<0.05). Body mass index was in the normal range in 35.3% of men, and 55.9% of women. In both men and women, blood pressure, blood sugar, total cholesterol and triglyceride were positively correlated with BMI. waist circumference, and Broca's index(p<0.01). However HDL. choloesterol was correlated negatively (p< 0.01). Using ROC curve, the calculated waist circumferences were 84 cm in men(sensitivity 61.4% and specificity 64.1%) and 74 cm in women(sensitivity 65.0% and specificity 73.2%). The age adjusted prevalences of the metabolic syndrome as defined by NCEP ATP III were different for men(6.4%) and women(14.6%). The prevalence increased from 1.2% among participants aged 20 through 29years to 15.0% among participants aged over 60years in men(p<0.05) and from 1.6% to 27.4% respectively, in women. The age adjusted prevalences, as defined by using the waist circumference that was recommended by WHO's regional office for the western Pacific, were 10.6% in men and 18.5% in women. The age adjusted prevalences, as defined by using the waist circumference that was calculated by the ROC curves, were 17.1% in men and 22.4% in women. And All prevalences were increased following increased BMI and Broca's index. Conculsions : The prevalence of metabolic syndrome in some Korean adults was lower than that in western adults. Nevertheless because waist circumference was differed among race and region, application of the same criteria was not proper. Morcover, a higher awareness was required in women, because the prevalence of metabolic syndrome was rapidly increased with increment of age.

• Journal of Gastric Cancer
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• 제9권4호
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• pp.167-171
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• 2009

목적: 정상인과 위암 환자의 혈중 Pepsinogen (PG)농도를 비교 분석하여 선별검사로서 이용가능성 및 위암의 임상 조직학적 요소와의 상관 관계를 알아보고자 하였다. 대상 및 방법: 2008년 11월부터 2009년 5월까지 대구가톨릭대학병원에서 내시경상 특이소견이 없는 정상인과 위선암 환자의 수술 전 혈중 PG농도를 측정하였다. 위암진단의 선별검사로서의 이용가능성을 알아 보기 위해 receiver operator characteristics (ROC) curves를 이용하여 가장 유용한 검사법을 선별하였고, 위암 조직과의 상관관계를 알아보기 위해 특정 기준치에 따라 임상 조직학적 요소를 비교 분석하였다. 결과:선별검사로서 혈중 PG I/II 비율이 가장 유용하였고, 기준치에 따른 민감도, 특이도는 81.8%, 82%로 나타났다. 임상 조직학적 요소 중 Lauren분류에 따른 종양의 아형(P=0.003), TNM 병기의 T 병기(P=0.001), 및 종양주위의 만성 위축성 위염(P=0.036)을 동반한 위선암이 특정기준치(cut off point)값에 의미 있는 관련을 보였다. 결론: 본 연구는 정상 대조군의 수가 적어 선별검사로서 혈중 PG측정의 유용성을 논하기에는 부족하나, 위암의 선별검사로서 이용 가능성 및 임상 조직학적 요소와 의미 있는 관련을 보여 차후 추가연구가 필요할 것으로 생각한다.

• 한국토양비료학회지
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• 제41권4호
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• pp.273-278
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• 2008

이 연구는 Tempe 압력셀에서 1-단계 유출법을 이용하여 불포화수리전도도 추정모형인 van Genchten 모형과 Campbell 모형을 비교하고자 수행하였다. 토양 코아(컬럼)는 서울대학교 농업생명과학대학 부속 사과 과수원에 위치한 송정통 (the fine loamy, mesic family of Typic Hapludults) 의 Ap1, B1, C 층에서 채취하였다. 각 층위의 컬럼들에 대해 포화수리전도도를 측정하고 Tempe 압력셀에서 수분보유곡선을 측정한 후 최소좌승법으로 모형의 변수를 도출하였다. 수분보유곡선에서 모형과 측정치는 잘 적합하였고 포화근처에서 Campbell 모형의 적합도가 van Genchten 모형보다 약간 더 좋았다. Campbell 모형의 불포화수리전도도가 van Genchten 모형보다 높게 추정되었으며 1-단계 유출법의 불포화수리전도도는 C층에서 van Genchten 모형과 잘 적합하였고 Ap1층, B1층에서는 두 모형의 중간에서 van Genchten에 약간 더 가까웠다. 따라서 불포화수리전도도 측정범위-10~-75kPa에서 van Genuchten 모형이 실측치와 더 적합하다 할 수 있었고, 포화근처에서는 수분보유곡선과의 적합도가 Campbell 모형이 더 높은 것으로 보아 상대적으로 수리전도도함수의 정확도가 높을 것으로 추측할 수 있었다.

• Journal of mucopolysaccharidosis and rare diseases
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• 제2권2호
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• pp.41-42
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• 2016

Today's mobile phones and tablet PCs offer a considerably wider range of functionalities than before. Mobile applications (apps) are increasingly used for managing various daily health tasks. Currently, more than 165,000 health-related apps are offered on all the stores of different platforms. Pf Jin and the Association for Research on MPS and Rare Diseases (AMARD) have helped Prader-Willi syndrome (PWS) families through medical information and family support since 2015. AMARD developed the first mobile application for Korean patients with PWS, which was released to a limited number of patients under the age of 3 and only provided to Android users. The first version of the PWS application focused on growth hormone therapy and the assessment of growth and development by parents in infant and early-childhood PWS patients. The 2016 version of the PWS application has been improved in many different ways. We have expanded the subjects of the application to late childhood and adolescent groups, changed the user interface accordingly, and made the application available for iOS users. We will show the specialized growth curves of older children with PWS. Therefore, patients with PWS over the age of 3 and their parents can assess the patients' growth. Additionally, we have upgraded the growth hormone therapy menu by improving the input system for the growth hormone therapy injection schedule and the daily growth profile (height and weight). We expect that the new version of the PWS application will help many PWS families cope with growth hormone therapy and evaluate the effects of growth hormones in better ways. Additionally, we are making a constant effort to provide more useful information about patients with PWS in many aspects.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.242-242
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• 2016

Magnetite, Fe3O4, is a ferrimagnet with a cubic inverse spinel structure and exhibits a metal-insulator, Verwey, transition at about 120 K.[1] It is predicted to possess as half-metallic nature, 100% spin polarization, and high Curie temperature (850 K). Cobalt ferrite is one of the most important members of the ferrite family, which is characterized by its high coercivity, moderate magnetization and very high magnetocrystalline anisotropy. It has been reported that the CoFe2O4/Fe3O4 bilayers represent an unusual exchange-coupled system whose properties are due to the nature of the oxide-oxide super-exchange interactions at the interface [2]. In order to evaluate the effect of interface interactions on magnetic and transport properties of ferrite and cobalt ferrite, the CoFe2O4/Fe3O4 superlattices on MgO (100) substrate have been fabricated by molecular beam epitaxy (MBE) with the wave lengths of 50, and $200{\AA}$, called $25{\AA}/25{\AA}$ and $100{\AA}/100{\AA}$, respectively. Streaky RHEED patterns in sample $25{\AA}/25{\AA}$ indicate a very smooth surface and interface between layers. HR-TEM image show the good crystalline of sample $25{\AA}/25{\AA}$. Interestingly, magnetization curves showed a strong antiferromagnetic order, which was formed at the interfaces.

• Journal of Preventive Medicine and Public Health
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• 제10권1호
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• pp.142-149
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• 1977

To use basic data for health planning and evaluation of Kangwha community health project of Yonsei University, a study on death rates and causes of death were investigated in two townships (Naega and Sunwon Myuns) in Kangwha County from April 1, 1975 to March 31, 1977 All death was identified and reported by family health workers who are living in each village and 2 trained public health nurses confirmed the death. The causes of death were investigated by 2 public physicians. Total number of deaths for 2 years was 230 and the followings are brief summary of the study. 1. Age-adjusted crude death rates of study area were 8.69 per 1,000 population in 1975 and 7.18 per 1,000 population in 1976. Age-adjusted crude death rates for male were 9.18 in 1975 and 6.38 in 1976 and for female were 8.33 and 7.80 per 1,000 population 2. Age specific death rate curves by year and sex showed 'U' shapes. 3. Infant and neonatal death rates were 30.08 and 22.56 per 1,000 live births in 1975, and the rates in 1976 were 18.18 and 13.64. 4. The most common cause of death was cerebrovascular disease and average cause specific death rate for the disease was 215.5 per 100,000 population. 5. Four leading causes of death were non-infectious origin; cerebrovascular disease, malignant neoplasms, senility and suicide. Pulmonary tubeculosis and pneumonia occupied 5th and 9th causes of death. 6. Stomach cancer and hepatoma occupied 61.3% of total death due to malignant neoplasms. 7. Most frequent cause of neonatal death was birth injury. Two deaths due to tetanus were found in 1975, but no death due to this disease was found in 1976. 8. About half of deceased received care from physician before death.