• 노동경제논집
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• 제30권2호
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• pp.87-118
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• 2007

본 논문에서는 한국직업능력개발원의 "전문대 및 대학 졸업생 경제활동상태 추적조사" 2005년 자료를 주로 이용하여 대학서열화와 노동시장 성과 간의 관계를 지방대 졸업생에 대한 임금차별을 중심으로 분석하였다. 주요 결과로는 첫째, 지방대학 졸업생 월평균 임금은 174.77만원으로 수도권대학 졸업생에 비해 11.5% 낮았으나 지방대학의 낮은 수능점수에 상당 부분 기인하였다. 둘째, 위계선형모형(Hierarchical Linear Model)을 적용하여 학교의 임금효과를 추정한 결과 개인간 임금차이의 12.2%만이 학교간 차이에 기인하는 것으로 나타나 학교효과가 예상보다 작음을 확인하였다. 셋째, 대학 진학시의 선택편의(selection bias)를 고려한 Heckman형 2SLS 임금함수를 추정한 후 Neumark 임금분해를 시도한 결과 수도권대학과 지방대학 졸업생 간 임금격차는 전적으로 수도권대학 졸업생의 인적 속성과 직업 속성상의 우위에 기인하였으며, 특히 수도권에 집중된 상위권 대학의 영향이 결정적으로 작용하였다. 넷째, 분위회귀 기법을 적용하여 임금분위별 지방대생 차별을 분석한 결과 임금분위와 무관하게 대체로 -4.01%~-2.51% 범위의 임금차별이 관찰되었다.

• 천문학회지
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• 제48권1호
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• pp.83-92
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• 2015

Recent large scale surveys such as Sloan Digital Sky Survey have produced homogeneous samples of multiple-image gravitationally lensed quasars with well-defined selection effects. Statistical analysis on these can yield independent constraints on cosmological parameters. Here we use the image separation statistics of lensed quasars from Sloan Digital Sky Survey Quasar Lens Search (SQLS) to derive constraints on cosmological parameters. Our analysis does not require knowledge of the magnification bias, which can only be estimated from the detailed knowledge on the quasar luminosity function at all redshifts, and includes the consideration for the bias against small image separation quasars due to selection against faint lens galaxy in the follow-up observations for confirmation. We first use the mean image separation of the lensed quasars as a function of redshift to find that cosmological models with extreme curvature are inconsistent with observed lensed quasars. We then apply the maximum likelihood test to the statistical sample of 16 lensed quasars that have both measured redshift and magnitude of lens galaxy. The likelihood incorporates the probability that the observed image separation is realized given the luminosity of the lens galaxy in the same manner as Im et al. (1997). We find that the 95% confidence range for the cosmological constant (i.e., the vacuum energy density) is $0.72{\leq}{\Omega}_{\Lambda}{\leq}1.0$ for a flat universe. We also find that the equation of state parameter can be consistent with -1 as long as the matter density ${\Omega}_m{\leq}0.4$ (95% confidence range). We conclude that the image separation statistics incorporating the brightness of lens galaxies can provide robust constraints on the cosmological parameters.

• 노동경제논집
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• 제23권2호
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• pp.127-151
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• 2000

한국노동패널 데이터를 사용하여 Bivariate Logit 및 Heckman의 표본 선택편의모형(selection bias model) 분석을 해 본 결과, 과거의 직업훈련의 경험은 일반 전체에게 한국노동패널 조사시점 현재의 취업상태에 있을 가능성에 양(+)의 영향을 미치는 것으로 나타났다. 그러나 직업훈련의 경험자들에게 국한시켜 볼 때 직업훈련을 공공기관에서 받거나 공공기관이 비용을 부담할 경우는 실망실업자를 실업자로 간주하고 독립변수에 산업더미를 포함시키는 경우와 그렇지 않은 경우가 다른 결과를 보여주고 있다. 즉 전자의 경우 공공부문에서 직업훈련을 받거나 비용을 부담하는 것이 취업 가능성에 영향을 못 주지만 후자의 경우는 공공기관에서 직업훈련을 받거나 비용을 부담하는 것이 민간부문에서보다 더 높은 취업 가능성을 가지고 있었다. 임금상승 효과는 전체적으로 볼 때 양(+)의 영향을 미치는 것으로 나타났다. 하지만 제조업과 서비스업에 각각 한정시켜 보았을 때는 직업훈련은 임금 상승 효과가 없는 것으로 나타났고, 직업훈련기관이 공공부문인가 여부와 직업훈련의 비용을 공공부문이 부담하는가 여부도 임금상승에 별다른 영향을 주지 못하는 것으로 나타났다.

• 대한본초학회지
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• 제36권5호
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• pp.37-46
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• 2021

Objective : This study aims to examine the effectiveness and safety of herbal medicines in upper respiratory tract infection by conducting systematic review against amoxicillin. Methods : Relevant randomized controlled trials (RCTs) published by December 2020 were searched in PubMED database. Study selection was conducted according to the PRISMA guideline. The Risk of Bias of the RCTs were evaluated based on the Cochrane criteria. Study selection and bias assessment were conducted independently by two researchers, and the third party was involved if there is a disagreement. Results : Three RCTs were included. Meta-analysis was not performed due to different specific disease and outcome measurements among the included studies. Herbal medicine showed statistically significant improvement in symptoms and endoscopic findings compared to amoxicillin in acute rhinosinusitis. In addition, herbal medicine showed statistically significant improvement in symptoms and a smaller dose of additional antibiotics in acute tonsillitis. However, herbal medicine showed no significant effects compared to amoxicillin in chronic sinusitis patients after functional endoscopic sinus surgery. In terms of adverse events, no significant difference was observed between the herbal medicine group and the amoxicillin group in all studies. Conclusion : Herbal medicine might be more effective than amoxicillin in the treatment of upper respiratory tract infection. Nevertheless, it is hard to clear that conclusion due to the fact that the collected studies were conducted on different specific diseases and herbal medicine, and that the included studies had flaws in the research methodology.

• 응용통계연구
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• 제7권1호
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• pp.149-158
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• 1994

커널 추정은 커널함수와 bandwidth에 의해서 결정이 된다. 그러나 평활의 정도를 조절하는 적절한 bandwidth를 찾는 것이 더욱 중요한 문제이다. 그러므로 이론적으로 최적의 bandwidth와 비교하여 실제자료에 잘 적용될 수 있는 적절한 bandwidth를 어떻게 찾느냐는 것이 문제가 된다. 본 논문에서는 평균제곱오차(mean square error)의 편의(bias)와 분산(variance)의 관계를 통하여 커널을 이용한 회귀선의 추정에 있어서 간단하고 효과적인 local bandwidth를 찾을 수 있는 알고리즘을 제안하였다.

• 한국항공우주학회지
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• 제43권1호
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• pp.88-95
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• 2015

본 논문에서는 액체 엔진의 혼합비 오차와 추진제 탑재 오차가 성능에 미치는 영향에 대해서 분석하였다. 75톤급 엔진 4개를 클러스터링하는 발사체 모델에 대해 이런 오차에 의해 발생하는 추진제 잔류량을 확률적인 Monte-Carlo 방법을 사용하여 계산하고 잔류량을 최소화할 수 있는 최적 연료 바이어스를 도출하였다. 다른 발사체에 사용된 근사식을 사용한 해석적인 방법과 비교함으로써 얻어진 결과의 타당성을 검토하였다.

• Clinics in Shoulder and Elbow
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• 제16권1호
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• pp.58-62
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• 2013

서론: 최근 임상 연구와 논문의 활성화 속에 높은 신뢰도를 보장하는 방법을 따르는 예들은 아직 많지 않다. 이에 연구의 편향을 최소화하는 무작위 추출의 개념과 바른 방법에 대해 알아보고자 한다. 대상 및 방법: 최근까지 발표된 무작위 추출에 대한 문헌 고찰을 통해 무작위 추출의 기본 개념 및 필요성을 정리하고 바른 무작위 추출을 위한 조건 및 무작위 추출의 종류별 방법들(단순 무작위 추출, 순열화 블록 무작위추출, 계층화)에 대해 살펴 보았다. 결과 및 결론: 무작위 추출은 임상 연구에서 편향을 줄이고 통계적 검사를 이용한 자료 분석의 보장된 유효성을 제공한다. 이렇듯 보다 신뢰도 높은 연구 결과를 도출해 낼 수 있는 방법인 무작위 추출에 대한 개념 재정립 및 바른 무작위 추출 방법의 제안은 연구자들에게 꼭 필요한 과정이라 할 수 있겠다.

• 대한간호학회지
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• 제47권2호
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• pp.143-163
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• 2017

Purpose: This study was a systematic review and meta-analysis designed to investigate effects of psychoeducational intervention for cancer survivors. Methods: Ten databases were searched. Two reviewers independently performed the selection of the studies, data extraction and assessment. The risk of bias was assessed using Cochrane Collaboration's tool. To estimate the effect size, meta-analysis of the studies was performed using Comprehensive Meta-Analysis and RevMan programs. Results: Of 18,781 publications identified, 35 met inclusion criteria, and 25 studies were used to estimate effect size of psychoeducational intervention. Effect sizes (standardized mean difference [SMD]) were heterogeneous and random effects models were used in the analyses. Psychoeducational intervention was effective for quality of life (n=2,410, ES=0.23; 95% CI: 0.09~0.37), coping and self-efficacy (n=179, ES=0.68; 95% CI: 0.26~1.11), anxiety (n=1,786, ES=-0.26; 95% CI: -0.37~-0.15), depression (n=1,910, ES=-0.28; 95% CI: -0.37~-0.18), and psychological distress (n=2,242, ES=-0.31; 95% CI: -0.46~-0.17). Subgroup analysis showed that counseling was the most effective intervention for quality of life, and behavioral therapy was an effective intervention for all positive and negative outcomes. Publication bias was not detected except for psychological distress. Conclusion: Psychoeducational intervention appears to be effective in improving quality of life and coping and self-efficacy, and it is effective in reducing psychological symptoms in cancer survivors. Behavioral therapy, especially, is commonly effective in improving psychosocial outcomes. However, low-quality evidence, variability in the designs of existing studies, and publication bias suggest that additional high-quality trials should be conducted in the future.

• Journal of Preventive Medicine and Public Health
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• 제43권2호
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• pp.185-192
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• 2010

Objectives: We conducted a meta-analysis to investigate the relationship between low external doses of ionizing radiation exposure and the risk of cancer mortality among nuclear power plant workers. Methods: We searched MEDLINE using key words related to low dose and cancer risk. The selected articles were restricted to those written in English from 1990 to January 2009. We excluded those studies with no fit to the selection criteria and we included the cited references in published articles to minimize publication bias. Through this process, a total of 11 epidemiologic studies were finally included. A publication bias was tested for using Egger's test. The homogeneity test was performed before the integration of each of the standardized mortality ratios (SMRs) and the result proved that the studies were heterogeneous. Results: We found significant decreased deaths from all cancers (SMR = 0.75, 95% CI = 0.62 - 0.90), all cancers excluding leukemia, solid cancer, mouth and pharynx, esophagus, stomach, rectum, liver and gallbladder, pancreas, lung, prostate, lymphopoietic and hematopoitic cancer. The findings of this meta-analysis were similar with those of the 15 Country Collaborative Study conducted by the International Agency for Research on Cancer. A publication bias was found only for liver and gallbladder cancer (p = 0.015). Heterogeneity was observed for all cancers, all cancers excluding leukemia, solid cancer, esophagus, colon and lung cancer. Conclusions: Our findings of low mortality for stomach, rectum, liver and gallbladder cancers may explained by the health worker effect. Yet further studies are needed to clarify the low SMR of cancers, for which there is no useful screening tool, in nuclear power plant workers.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1154-1154
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• 2001

Near infra-red (NIR) spectroscopy has been used for the non-invasive assessment of intact fruit for eating quality attributes such as total soluble solids (TSS) content. However, little information is available in the literature with respect to the robustness of such calibration models validated against independent populations (however, see Peiris et al. 1998 and Guthrie et al. 1998). Many studies report ‘prediction’ statistics in which the calibration and prediction sets are subsets of the same population (e. g. a three year calibration validated against a set from the same population, Peiris et al. 1998; calibration and validation subsets of the same initial population, Guthrie and Walsh 1997 and McGlone and Kawano 1998). In this study, a calibration was developed across 84 melon fruit (R$^2$= 0.86$^{\circ}$Brix, SECV = 0.38$^{\circ}$Brix), which predicted well on fruit excluded from the calibration set but taken from the same population (n = 24, SEP = 0.38$^{\circ}$Brix with 0.1$^{\circ}$Brix bias), relative to an independent group (same variety and farm but different harvest date) (n = 24, SEP= 0.66$^{\circ}$ Brix with 0.1$^{\circ}$Brix bias). Prediction on a different variety, different growing district and time was worse (n = 24, SEP = 1.2$^{\circ}$Brix with 0.9$^{\circ}$Brix bias). Using an ‘in-line’ unit based on a silicon diode array spectrometer, as described in Walsh et al. (2000), we collected spectra from fruit populations covering different varieties, growing districts and time. The calibration procedure was optimized in terms of spectral window, derivative function and scatter correction. Performance of a calibration across new populations of fruit (different varieties, growing districts and harvest date) is reported. Various calibration sample selection techniques (primarily based on Mahalanobis distances), were trialled to structure the calibration population to improve robustness of prediction on independent sets. Optimization of calibration population structure (using the ISI protocols of neighbourhood and global distances) resulted in the elimination of over 50% of the initial data set. The use of the ISI Local Calibration routine was also investigated.