A study on the reliability improvement of PAMS standard gas

서동기,김봄이,박정윤,이상호 한국분석과학회 2022 학술대회논문집 Vol.2022 No.11

태변성 복막염 : 산전 초음파 소견과 임상적 중요성 Prenatal Sonographic Findings and Their Clinical Significance

서동기,김성일,오수영,문정빈,김미하,박중신,전종관,윤보현,신희철 대한산부인과초음파학회 2000 대한산부인과초음파학회지 Vol.2 No.2

폐면을 이용한 느타리버섯 재배

서동기 慶北大學校 農業開發大學院 2000 最高農業經營者課程 論文集 Vol.6 No.-

대구경 볼트와 와이어텐션을 이용한 슬래브 보강공법에 관한 실험적 연구

서동기,노현섭,김상모,이창남,김상섭 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

As time goes up, structural capacity of members decreases in reinforced concrete structures. The deterioration of the capacity is mainly due to the poor construction, corrosion of steel bars and the neutralization of concrete due to environmental pollution, etc. This deterioration is unavoidable, thus it is necessary to develop the method for repair and retrofit of structures in order to ensure structural safety of members. The purpose of this paper is to investigate the load-deflection, ultimate strength, failure mode, and energy absorption capacity of reinforced concrete slabs subject to load experimentally for several variables and grasp the problem of concrete slabs strengthened with large diameter bolts and wire tensioning. And propose foundational research data for4 strengthening reinforced concrete slabs. The test result shows that the capacity of anchorage is controlled by bearing capacity of concrete under the anchorage or punching shear around the anchorage. And the gap between bolts and core hole must be filled to prevent slip and rotation of anchorage.

수평전도관에서 열전달에 의한 엔트로피발생에 관한 연구

서동기,김선정,권순석 대한기계학회 1987 대한기계학회 춘추학술대회 Vol.- No.-

가스상 HF 인증표준물질 개발

서동기,박정윤,이선영,최명기,이상호 한국분석과학회 2022 학술대회논문집 Vol.2022 No.5

모형명세화 오류와 소표본에서 구조방정식모형 모수추정 방법들 비교: 모수추정 정확도와 이론모형 검정력을 중심으로

서동기,정선호,Seo, Dong Gi,Jung, Sunho 한국데이터정보과학회 2017 한국데이터정보과학회지 Vol.28 No.5

구조방정식모형은 사회과학 및 행동과학 연구 분야에서 이론검정을 위해 주로 사용되는 통계방법이다. 최근 이 통계기법에 대한 방법론적 이슈로서 모형명세화 오류와 소표본 문제가 부각되고 있다. 그런데 이 문제들이 구조방정식모형의 대표 추정 방법인 최대우도법에 위한 이론검정에 어떤 영향을 주는지에 대해 여전히 명확하지 않다. 따라서 본 연구에서 최대우도법 그러고 이에 대한 대안으로 개발된 2단계최소자승법과 2단계능형최소자승법을 정확도와 검정력 관점에서 시뮬레이션을 통해 체계적으로 비교해 본다. 이 실험 결과에 따르면, 모형이 정확하게 설정된 경우, 정확도 기준에서 추정방법들 간의 차이는 미미했다. 하지만 모형오류가 발생한 경우, 2단계능형최소자승법은 다른 방법들보다 표본 크기가 작을 때 훨씬 더 정확한 모수추정치를 산출해 내었다. 그러고 이 방법은 명세화 오류에 관계없이 표본 크기가 작을 때에도 제 2종 오류 (Type II error) 수준이 상대적으로 작거나 만족할만한 수준의 검정력을 보여주었다. 이에 반해 다른 두 방법들은 표본이 작은 경우 또는 명세화 오류가 있는 경우 상당히 높은 수준의 제 2종 오류를 나타내었다. Structural equation modeling (SEM) is a basic tool for testing theories in a variety of disciplines. A maximum likelihood (ML) method for parameter estimation is by far the most widely used in SEM. Alternatively, two-stage least squares (2SLS) estimator has been proposed as a more robust procedure to address model misspecification. A regularized extension of 2SLS, two-stage ridge least squares (2SRLS) has recently been introduced as an alternative to ML to effectively handle the small-sample-size issue. However, it is unclear whether and when misspecification and small sample sizes may pose problems in theory testing with 2SLS, 2SRLS, and ML. The purpose of this article is to evaluate the three estimation methods in terms of inferences errors as well as parameter recovery under two experimental conditions. We find that: 1) when the model is misspecified, 2SRLS tends to recover parameters better than the other two estimation methods; 2) Regardless of specification errors, 2SRLS produces small or relatively acceptable Type II error rates for the small sample sizes.

The accuracy and consistency of mastery for each content domain using the Rasch and deterministic inputs, noisy “and” gate diagnostic classification models: a simulation study and a real-world analysis using data from the Korean Medical Licensing Exami

서동기,Jae Kum Kim 한국보건의료인국가시험원 2021 보건의료교육평가 Vol.18 No.-

Purpose: Diagnostic classification models (DCMs) were developed to identify the mastery or non-mastery of the attributes required for solving test items, but their application has been limited to very low-level attributes, and the accuracy and consistency of high-level attributes using DCMs have rarely been reported compared with classical test theory (CTT) and item response theory models. This paper compared the accuracy of high-level attribute mastery between deterministic inputs, noisy “and” gate (DINA) and Rasch models, along with sub-scores based on CTT. Methods: First, a simulation study explored the effects of attribute length (number of items per attribute) and the correlations among attributes with respect to the accuracy of mastery. Second, a real-data study examined model and item fit and investigated the consistency of mastery for each attribute among the 3 models using the 2017 Korean Medical Licensing Examination with 360 items. Results: Accuracy of mastery increased with a higher number of items measuring each attribute across all conditions. The DINA model was more accurate than the CTT and Rasch models for attributes with high correlations (>0.5) and few items. In the real-data analysis, the DINA and Rasch models generally showed better item fits and appropriate model fit. The consistency of mastery between the Rasch and DINA models ranged from 0.541 to 0.633 and the correlations of person attribute scores between the Rasch and DINA models ranged from 0.579 to 0.786. Conclusion: Although all 3 models provide a mastery decision for each examinee, the individual mastery profile using the DINA model provides more accurate decisions for attributes with high correlations than the CTT and Rasch models. The DINA model can also be directly applied to tests with complex structures, unlike the CTT and Rasch models, and it provides different diagnostic information from the CTT and Rasch models.

미국의 부동산시장 - 펜더믹 이후의 미국과 우리나라 부동산시장 -

서동기 국제부동산정책학회 2020 토지와건물 Vol.35 No.-

The real estate market is so chaotic that it is hard to predict due to corona. The rise in housing prices is partly due to lack of supply and price formation due to location, but the downturn in commercial real estate seems impossible to predict a recovery time. Consumer prices rose only 0.6 percent in January, following 0.4 percent in 2019 and 0.5 percent last year. However, housing, stocks, cryptocurrency, oil prices, daily necessities, etc. are almost on the rise. Inflation is like an “invisible tax” since only salaries remain the same. It is time to make every effort to manage risks in preparation for the return of inflation in 30 years. The nature of the problem is that we will not artificially raise interest rates, which could drive the economy into a catastrophe, but we cannot just monitor the state of inflation.

한국판 PCI 검사1)의 타당화 연구 : 국내 직무장면을 중심으로

서동기,김예실,유대열,임다현 한국경영컨설팅학회 2018 경영컨설팅연구 Vol.18 No.2

본 연구의 목적은 성격의 5요인을 기반으로 한 Personality Characteristics Inventory(PCI) 검사를 한국판으로 타당화 하는 것이다. PCI는 서 구 직무 장면에서 성격이 업무성과를 예측하는 것을 입증한 검사로서, 기업조직과 학계에서 활발하게 사용되고 있다. 본 연구에서는 국내 컨설팅 업체 및 바이오벤처회사 직원 145명을 대상으로 PCI 검사를 타당화 하였다. 번역 및 역번역 과정을 통하여 번안타 당도를 확보하였고, 중간 수준 이상의 내적일치 신뢰도 및 5요인 12하위요인 구조를 확인하였다. 상사가 부하직원의 과업수행 및 조직시민행동 을 평정하게 하여 이를 준거로 회귀분석을 실시함으로써 준거타당도를 확보하였다. 성격의 5요인에서는 원만성이 과업수행 및 제안활동을 정적 으로 예측하고, 성실성이 대인지향 및 조직지향 조직시민행동을 정적으로 예측하는 것으로 나타났다. 반면 외향성은 조직지향 조직시민행동을 부적으로 예측하고, 안정성은 과업수행, 대인지향 및 조직지향 조직시민행동을 부적으로 예측하는 것으로 나타났다. 하위 12요인에서 보면, 자 신감이 과업수행, 제안활동, 대인지향 및 조직지향 조직시민행동을 부적으로 예측하는 것으로 나타났다. 마지막으로 본 연구의 제한점을 논의하고, 추후 보다 완성도 있는 연구를 위한 제안을 하였다. The purpose of this study is to validate the Personality Characteristics Inventory (PCI) in Korean version. PCI which is proved to predict performances inWesternwork settings has been actively used in business organizations and academia. In this study, the PCI was validated for the subject of 145 consultants and bio-venture employees in Korea. The translation validity was obtained through translation and back-translation processes. The internal consistency reliability at the intermediate level and the construct of the 5 factors and 12 sub factors were confirmed. The criterion validity of the in-role behavior and OCBwith supervisor ratings was obtained by regression analysis. In the 5 factor of personality, Agreeableness predicted in-role behavior and voice in the positive way, and Conscientiousness predicted toward individuals OCB and toward the organization OCB in positive way. On the other hand, Extroversion predicted toward the organization OCB in negative way, and Emotional Stability predicted in-role behavior, toward individuals OCB and toward the organization OCB in negative way. In the sub 12 factors, Self Confidence predicted in-role behavior, voice, toward individuals OCB, and toward the organizationOCB as negatively. Finally, the limitations of this studywere discussed and proposals formore complete researchweremade.