• 응용통계연구
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• 제27권3호
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• pp.501-512
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• 2014

상당수의 사업체 조사는 절사표본설계법을 사용하고 있다. 이는 절사표본설계법에서 얻은 전수층이 많은 정보를 포함하고 있어 전체 표본크기를 최소화 할 수 있는 장점이 있기 때문이다. 그러나 최근 전수층에 포함된 사업체들의 무응답률이 높아감에 따라 전수층이 가지고 있는 장점에 한계가 나타나고 있다. 이에 Lee (2011), Shin과 Lee (2013)는 표본설계 단계에서부터 주어진 허용오차를 만족하면서 전수층 규모를 최소화하는 연구를 실시하였다. 본 연구에서는 주어진 허용오차를 만족하고 Hidiroglou (1986)가 제안한 방법으로 산출 된 표본크기를 고정한 상태에서 표본층 분산에 알려진 함수를 적합하여 전수층 크기를 최소화하는 새로운 최적 절사점을 제안하였다. 또한 Hidiroglou (1986)와 Shin과 Lee (2013)가 제안한 절단분포를 이용한 방법과 본 연구에서 제안한 방법을 모의실험과 사례연구를 통해 비교하였다.

• 중환자간호학회지
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• 제16권3호
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• pp.24-33
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• 2023

Purpose : This study aims to establish an optimal cut-off score on the Braden scale for the assessment of pressure injury to detect pressure injury risks among inpatients in a South Korean tertiary hospital. Methods : This retrospective study used electronic medical records, from January to December 2022. A total of 654 patients were included in the study. Of these, 218 inpatients with pressure injuries and 436 without pressure injuries were classified and analyzed using 1:2 Propensity Score Matching (PSM), and the generalized estimating equation was performed using SPSS Version 26 and the R Machlt package program. Results : The cut-off value on the Braden scale for distinguishing pressure injury was 17 points, and the AUC (area under the ROC curve) was 0.531 (0.484-0.579). The sensitivity was 56.6% (45.5-67.7%) and the specificity was 69.7% (66.0-73.4%). With 17 points, the Braden scale cut-off distinguished those who had pressure injuries from those who did not at the time of admission (p < .03). In the pressure injury group, the Braden score on the day of the pressure injury was 14, with significant results in all subcategories except the moisture category. Conclusion : Our findings revealed that a cut-off value of 17 was optimal for predicting the risk of pressure injuries among tertiary hospital inpatients. Future studies should evaluate the optimal cut-off values in different clinical environments. Additionally, it is necessary to conduct multicenter large sample studies to verify the effectiveness of a 17 value in PI risk assessments.

• 대한유전성대사질환학회지
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• 제14권2호
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• pp.150-155
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• 2014

The measurement of $17{\alpha}$-hydroxyprogesterone ($17{\alpha}$-OHP) in a dried blood spot on filter paper is an important for screening of congenital adrenal hyperplasia (CAH). Since high levels of $17{\alpha}$-OHP are frequently observed in premature infants without congenital adrenal hyperplasia, we evaluated cuts-off based on birth weight and performed validation. Birth weight and $17{\alpha}$-OHP concentration data of 292,204 newborn screening subjects in Greencross labopratories were analyzed. The cut-off values based on birth weight were newly evaluated and validated with the original data. The mean $17{\alpha}$-OHP concentration were 7.25 ng/mL in very low birth weight (VLBW) group, 4.02 ng/mL in low birth weight (LBW) group, 2.53 g/mL in normal birth weight (NBW) group, and 2.24 ng/mL in heavy birth weight (HBW) group. The cut-offs for CAH were decided as follows: 21.12 ng/mL for VLBW and LBW groups and 11.14 ng/mL for NBW and HBW groups. When applied new cut-offs for original data, positive rates in VLBW and LBW groups were decreased and positive rates in NBW and HBW groups were increased. The cut-offs based on birth weight should be used in the screening for CAH. We believe that our new cut-off reduce the false positive rate and false negative rate and our experience for cut-off set up and validation will be helpful for other laboratories doing newborn screening test.

• 사상체질의학회지
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• 제26권4호
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• pp.365-378
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• 2014

Objectives This study was performed to investigate the cut-off values of abdominal circumference and Body Mass Index(BMI) according to Sasang Constitution. Methods A total of 1,773 persons, namely 440 male people and 1,333 female people, in ages from 40 to 69 years old, participated in this research. They are all included in the community based Genomic cohort in Wonju in years from 2006 to 2013. The diagnostic criteria of metabolic syndrome was used followed by the National Cholesterol Education Program in Adult Treatment Panel III (NCEP ATP III) and Asian pacific guideline for only abdominal obesity. Results The prevalence of metabolic syndrome was 34.8% for men and 37.6% for women in this research. Taeeumin was the highly significant risk type for the metabolic syndrome in both sexes. Cut-off values of abdominal circumference were 88.3 cm in men, 80.3 cm in women, and cut-off values of BMI were $24.2kg/m^2$ in men and $25.3kg/m^2$ in women. For men, cut-off values of abdominal circumference were 79.5cm in Soyangin, 88.8 cm in Taeeumin and 79.5 cm in Soeumin, and cut-off values of BMI were $23.2kg/m^2$ in Soyangin, $25.6kg/m^2$ in Taeeumin and $20.6kg/m^2$ in Soeumin. For women, cut-off values of abdominal circumference were 76.3 cm in Soyangin, 80.3 cm in Taeeumin and 76.8 cm in Soeumin, and cut-off values of BMI were $22.4kg/m^2$ in Soyangin, $24.9kg/m^2$ in Taeeumin and $21.3kg/m^2$ in Soeumin. Conclusions Although 90 cm in men, 80 cm in women as an Asian pacific guideline were regarded as quite approximate to the mean value of abdominal circumference and $25kg/m^2$ to BMI. But if the results could be allocated in terms of the Sasang constitutional method, the cut-off values for Soyangin and Soeumin should be lowered than now.

• 한국지반환경공학회 논문집
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• 제23권5호
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• pp.33-39
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• 2022

오염물질이나 지하수의 흐름 및 유출의 차단, 해수 침투 방지 및 노후화된 제체의 보수·보강 등을 목적으로 활용되는 Cement-Bentonite 차수벽에 혼합되는 시멘트 일부를 GGBS로 치환하여 사용하는 Slag-Cement-Bentonite 차수벽은 높은 강도와 낮은 투수계수, 우수한 내구성 및 내화학성 등의 여러 장점으로 지하수 제어가 필요한 여러분야에서 다양하게 활용되고 있다. 그러나 이와같은 장점에도 불구하고 국내에서는 Slag-CB 차수벽에 대한 다양한 연구가 이루어지지 않아 적용사례가 많지 않으며, 특히, 시멘트를 대체하여 혼합되는 GGBS는 생산되는 국가에 따라 성질이 상이하여 국내 Slag-CB 차수벽의 활용성을 높이기 위해서는 국내에서 생산되는 GGBS를 활용한 Slag-CB 차수벽에 대한 다양한 연구가 필요한 실정이다. 이에 본 연구에서는 Slag-CB 차수벽의 활용성을 향상시키기 위해 국내에서 생산되는 GGBS를 혼합한 Slag-CB 차수벽의 GGBS 치환율에 따른 블리딩율, 응결시간, 강도 및 차수성 등을 평가하였다. 그 결과, 국내에서 생산된 GGBS를 혼합한 Slag-CB 차수벽은 CB 차수벽에 비해 낮은 블리딩율과 우수한 강도 및 차수성을 보였으며, 이러한 성능향상은 GGBS 치환율이 높을수록 더욱 효과적인 것으로 분석되었다.

• 대한관절경학회지
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• 제7권2호
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• pp.215-219
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• 2003

목적 : 단순 방사선 사진에서 슬관절 외측 원판형 연골판을 진단하는데 도움이 되는 새로운 방사선 소견인 대퇴외과 절삭 징후(cut-off sign)를 관찰하여 이를 보고하고, 이의 진단적 의의를 특이도, 민감도, 양성 예측도, 음성 예측도와 함께 보고하고자 한다. 대상 및 방법 : 관절경 시술로 확진 된 50예의 완전 원판형 연골군과 50예의 정상 대조군을 대상으로 하였으며, Tunnel view에서 보이는 대퇴 외과와 내과의 내측부의 최장 길이를 측정하여 비율을 비교 분석하였다. 결과 : 원판형 연골군에서 대퇴 내과부 길이와 외과부 길이의 비율의 평균은 0.716 이였으며, 정상 대조군에서는 0.902 이었다. 이를 T-test로 분석했을 때, t-value는 -11.13 (p<0.0001)로 두 군간에 매 우 유의 한 차이를 나타내었으며, 또한 경계값(cut point)을 0.8로 하여 chi-square test로 분석했을 때 통계적으로 두 군간에 유의한 차이가 있었으며, 민감도 $76\%$, 특이도 $100\%$였으며, 양성 예측도 $100\%$, 음성 예측도 $80.6\%$로 나타났다. 절삭 징후는 육안적으로도 뚜렷한 차이를 보여 원판형 외측 반월상 연골을 단순 방사선 사진에서 진단할 수 있는 매우 좋은 간접적인 소견이라고 생각한다. 결론 : 대퇴 외과 절삭 징후는 단순 방사선 검사의 Tunnel view에서 원판형 연골을 진단할 수 있는 좋은 방사선 소견이며, $100\%$의 특이도와 $100\%$의 양성 예측도를 나타내는 우수한 진단소견으로 판단된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.85-92
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• 2003

Generally, ordinary portland cement(OPC) is widely used for grouting to reduce permeability of ground under the foundations of structures. But, it is hard to be injected into the microscopic voids, fissures and crevices in soil or rock formation for the OPC material. Therefore new method what is called MSG(Micro Silica Grouting) has been developed recently to improve the weak point of the OPC material. In this case study, in order to verify performance of the MSG's water cut-off, trial injections were performed in rear of CIP(Cast in Place Pile) on the site A(weathered soil) and B(alluvial soil) that are constructed for the subway No. 9 nowadays. To take the proper grouting method of the MSG in the trial injecting, the injections are carried out for grouting types(constant pressure or fixed Quantity) and grouting methods(1.5shot or 2.0shot) and to confirm the effects of water cut-off and the injection range of the MSG, the tests of permeability and indicator(phenolphthalein) response were performed before and after the injection. Through the tests results, we could affirm the effects of water cut-off of the MSG and the injection range for the weathered and alluvial soil layers near the Han River. Finally we could make sure the application of the MSG method in actual construction under the layers.

• 화약ㆍ발파
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• 제30권2호
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• pp.77-85
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• 2012

본 시공사례는 목포에 위치한 한국제분 14기 Silo를 연속적 발파해체를 수행한 것이다. 주변현황을 고려하여 붕괴방향은 종방향으로 계획을 수행하였고, 좁은 공간에서 1기 Silo 당 발파 공수가 많아서 발파에 의한 Cut-off 문제, 거동에 관한 문제 및 구조물이 거동 후 파쇄에 대한 문제점이 고려되었다. 이에 14기의 Silo를 2차로 구분하여 발파를 하였다. 1차 A-Section 발파에서는 연결용 도폭선의 Cut-off 인하여 2회 발파를 수행하여 붕괴를 시키고, 이를 개선하여 2차 B-Section 발파 때에는 한 번에 원하는 방향으로 안전하게 시공한 사례이다.

• 대한기계학회논문집A
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• 제24권2호
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• pp.338-346
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• 2000

Although the net-shape molding of composites is generally recommended, molded composites are frequently required cutting or grinding due to the dimensional inaccuracy for precision machine elements . During the composite machining operations such as cutting and grinding, the temperature at the cutting point may increase beyond the allowed limit due to the low thermal conductivity of composites, which might degrade the matrix of composite. Therefore, in this work, the temperature at the cutting point during cut-off grinding of carbon fiber epoxy composites was measured. The cutting force and surface roughness were also measured to investigate the cut-off grinding characteristics of the composites. The experiments were performed both under dry and wet grinding conditions with respect to cutting speed and feed rate. From the experimental investigation, the optimal conditions for the composite cut-off grinding were suggested.

• 소성∙가공
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• 제14권1호
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• pp.37-42
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• 2005

In order to invstigate the influence of die design variables on the quality of the sheared surface in cutting of sandwich sheet metals, the cut-off operation is carried out, which is the typical shearing process in sheet metal forming technology. For experiments we made the cut-off die which can be easily adjusted for die design variables such as blankholding force, pad force and clearance. The sandwich sheet metals considered are clad304(STS304-Al1050-STS304) and anti-vibration sheet metal. The shearing process is visualized by the computer vision system installed in front of the cut-off die and the sheared surface is measured and quantitatively compared with the help of the optical microscope after cut-off operation. From test results it is shown that the shearing mechanisms are different according the material of which sandwitch sheet metal is composed. The influence of die design variable is explored and we found optimal conditions for both sandwich sheet metals. It is expected that this investigation can be utilized to get the better sheared surface.