A study on the resative efficiecy of the sequential probability test and the fixed sample test

Changsoon Park 중앙대학교 경제연구소 1988 經濟論文集 Vol.- No.2

A Combined Process Control Procedure by Monitoring and Repeated Adjustment

Park, Changsoon 한국통계학회 2000 Communications for statistical applications and me Vol.7 No.3

Statistical process control (SPC) and engineering process control (EPC) are based on different strategies for processes quality improvement. SPC reduces process variability by detecting and eliminating special causes of process variation. while EPC reduces process variability by adjusting compensatory variables to keep the quality variable close to target. Recently there has been needs for a process control proceduce which combines the tow strategies. This paper considers a combined scheme which simultaneously applies SPC and EPC techniques to reduce the variation of a process. The process model under consideration is an integrated moving average(IMA) process with a step shift. The EPC part of the scheme adjusts the process back to target at every fixed monitoring intervals, which is referred to a repeated adjustment scheme. The SPC part of the scheme uses an exponentially weighted moving average(EWMA) of observed deviation from target to detect special causes. A Markov chain model is developed to relate the scheme's expected cost per unit time to the design parameters of he combined control scheme. The expected cost per unit time is composed of off-target cost, adjustment cost, monitoring cost, and false alarm cost.

Linear filter model representations for integrated process control with repeated adjustments and monitoring

Changsoon Park 한국통계학회 2010 Journal of the Korean Statistical Society Vol.39 No.2

An integrated process control (IPC) procedure is a scheme which combines the engineering process control (EPC) and the statistical process control (SPC) procedures for the process where the noise and a special cause are present. The most efficient way of reducing the effect of the noise is to adjust the process by its forecast, which is done by the EPC procedure. The special cause, which produces significant deviations of the process level from the target, can be detected by the monitoring scheme, which is done by the SPC procedure. The effects of special causes can be eliminated by a rectifying action. The performance of the IPC procedure is evaluated in terms of the average run length (ARL) or the expected cost per unit time (ECU). In designing the IPC procedure for practical use, it is essential to derive its properties constituting the ARL or ECU based on the proposed process model. The process is usually assumed as it starts only with noise, and special causes occur at random times afterwards. The special cause is assumed to change the mean as well as all the parameters of the in-control model. The linear filter models for the process level as well as the controller and the observed deviations for the IPC procedure are developed here.

Design of On-line Process Control with Variable Measurement Interval

Park, Changsoon The Korean Statistical Society 2000 Journal of the Korean Statistical Society Vol.29 No.3

A mixed model with a white noise process and an IMA(0,1,1) process is considered as a process model. It is assumed that the process is a white noise in the absence of a special cause and the process changes to an IMA(0,1,1) due to a special cause. One useful scheme in measuring the process level is to use the variable measurement interval (VMI) between measurement times according to the value of the previous chart statistic. The advantage of the VMI scheme is to measure the process level infrequently when in control to save the measurement cost and to measure frequently when out of control to save the off-target cost. This paper considers the VMI scheme in order to detect changes in the process model from a white noise to an IMA(0,1,1). The VMI scheme is shown to be effective compared to the standard fixed measurement interval (FMI) scheme in both statistical and economic contexts.

Assessment of structural risks using the fuzzy weighted Euclidean FMEA and block diagram analysis

Park, Jihyun,Park, Changsoon,Ahn, Suneung Springer-Verlag 2018 INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TE Vol.99 No.9

Amplified circularly polarized phosphorescence from co-assemblies of platinum( <small>II</small> ) complexes

Park, Gyurim,Kim, Hyungchae,Yang, Hoichang,Park, Kyung Ryoul,Song, Inho,Oh, Joon Hak,Kim, Changsoon,You, Youngmin Royal Society of Chemistry 2019 Chemical Science Vol.10 No.5

<▼1><P>Co-assemblies of platinum(<SMALL>II</SMALL>) complexes produce amplified circularly polarized phosphorescence emission.</P></▼1><▼2><P>Molecules capable of producing zero-field circularly polarized phosphorescence (CPP) are highly valuable for chiroptoelectronic applications that rely on triplet exciton. However, the paucity of tractable molecular design rules for obtaining CPP emission has inhibited full utilization. We report amplification of CPP by the formation of helical co-assemblies consisting of achiral square planar cycloplatinated complexes and small fractions of homochiral cycloplatinated complexes. The latter has a unique Pfeiffer effect during the formation of superhelical co-assemblies, enabling versatile chiroptical control. Large dissymmetry factors in electronic absorption (<I>g</I><SUB>abs</SUB>, 0.020) and phosphorescence emission (<I>g</I><SUB>lum</SUB>, 0.064) are observed from the co-assemblies. These values are two orders of magnitude improved relative to those of individual molecules. In addition, photoluminescence quantum yields (PLQY) also increase by a factor of ten. Our structural, photophysical, and quantum chemical investigations reveal that the chiroptical amplification is attributable to utilization of both the magnetically allowed electronic transition and asymmetric coupling of excitons. The strategy overcomes the trade-off between <I>g</I><SUB>lum</SUB> and PLQY which has frequently been found for previous molecular emitters of circularly polarized luminescence. It is anticipated that our study will provide new insight into the future research for the exploitation of the full potential of CPP.</P></▼2>

Identification of indirect effects in the two-condition within-subject mediation model and its implementation using SEM

Park Eujin,Park Changsoon 한국통계학회 2023 Communications for statistical applications and me Vol.30 No.6

In the two-condition within-subject mediation design, pairs of variables such as mediator and outcome are observed under two treatment conditions. The main objective of the design is to investigate the indirect effects of the condition difference (sum) on the outcome difference (sum) through the mediator difference (sum) for comparison of two treatment conditions. The natural condition variables mean the original variables, while the rotated condition variables mean the difference and the sum of two natural variables. The outcome difference (sum) is expressed as a linear model regressed on two natural (rotated) mediators as a parallel two-mediator design in two condition approaches: the natural condition approach uses regressors as the natural condition variables, while the rotated condition approach uses regressors as the rotated condition variables. In each condition approach, the total indirect effect on the outcome difference (sum) can be expressed as the sum of two individual indirect effects: within- and cross-condition indirect effects. The total indirect effects on the outcome difference (sum) for both condition approaches are the same. The invariance of the total indirect effect makes it possible to analyze the nature of two pairs of individual indirect effects induced from the natural conditions and the rotated conditions. The two-condition within-subject design is extended to the addition of a between-subject moderator. Probing of the conditional indirect effects given the moderator values is implemented by plotting the bootstrap confidence intervals of indirect effects against the moderator values. The expected indirect effect with respect to the moderator is derived to provide the overall effect of moderator on the indirect effect. The model coefficients are estimated by the structural equation modeling approach and their statistical significance is tested using the bias-corrected bootstrap confidence intervals. All procedures are evaluated using function lavaan() of package \{lavaan\} in R.

상사무례 및 부하무례가 의료종사자의 조직몰입과 고객지향성에 미치는 영향

박창순(Changsoon Park),양위주(Wiijoo Yhang) 대한관광경영학회 2022 觀光硏究 Vol.37 No.7

본 연구는 의료관광산업에서 서비스를 제공하는 고객 접점에 있는 행정부, 의료종사자를 대상으로, 상사무례와 부하무례가 조직몰입과 고객지향성에 미치는 영향관계에 대한 실증적 연구를 통해, 의료관광 산업의 주요 핵심인 인적자원 관리에 관한 정책을 제안, 마련하고자 연구를 진행하였다. 부산시에 있는 외국인환자 유치 의료기관으로 등록된 의료기관의행정부에 근무하는 의료종사자를 대상으로 설문조사를 실시하였다. 조사는 대학병원, 병원, 의원, 요양병원으로 종별로 나누어, 2022년 8월 한 달 동안, 자기기입식 설문조사를 통해 이루어졌다. 설문지는 총 220부를 배부하여, 불성실하게 응답한 설문을 제외하고, 최종적으로 198부를 사용하였다. 수집된 데이터의 통계 처리를 위해 SPSS 25.0와 AMOS 25.0 통계패키지 프로그램을 사용하였다. 응답자의 인구통계학적 특성을 파악하기 위해 빈도분석(frequency analysis)을 실시하였다. 변수에 대한 신뢰성 및 타당성을 파악하기 위해 확인적 요인분석(confirmatory factor analysis)을 실시하였으며, 가설을 검증하기 위해 구조방정식모델(structural equation modeling)을 사용하였다. 연구 결과는 다음과 같다. 첫째, 상사무례는 조직몰입에 유의한 부(-)의 영향을 미치는 것으로 나타났다. 둘째, 부하무례는 조직몰입에 유의한 부(-)의 영향을 미치지 않는 것으로 나타났다. 셋째, 조직몰입은 고객지향성에 유의한 정(+)의 영향을 미치는 것으로 나타났다. 본 연구는 의료종사자를 대상으로, 상사무례와 부하무례가 조직몰입과, 고객지향성에 미치는 영향을 분석한 것에 학문적 의의가 있다. This study aimed at the administration and medical workers who are at the customer contact point providing services in the medical tourism industry. Through an empirical study on the effect of superior conduct and subordinate rudeness on organizational commitment and customer orientation, this study This study was conducted to propose and prepare policies on human resource management, which is the core. A survey was conducted on medical workers working in the administrative department of medical institutions registered as medical institutions for attracting foreign patients in Busan. The survey was divided into university hospitals, hospitals, clinics, and nursing hospitals by type, and for one month in August 2022, a self-report questionnaire was conducted. A total of 220 copies of the questionnaire were distributed, and 198 copies were finally used, excluding those who answered insincerely. For statistical processing of the collected data, SPSS 25.0 and AMOS 25.0 statistical package programs were used. Frequency analysis was performed to identify the demographic characteristics of respondents. Confirmatory factor analysis was performed to determine the reliability and validity of the variables, and structural equation modeling was used to test the hypothesis. The study results are as follows. First, it was found that superior management practices had a significant negative (-) effect on organizational commitment. Second, it was found that subordinate disrespect did not have a significant negative (-) effect on organizational commitment. Third, organizational commitment was found to have a significant positive (+) effect on customer orientation. This study has academic significance in analyzing the effects of boss and subordinate rudeness on organizational commitment and customer orientation targeting medical workers.

Fuzzy-FME을 이용한 항공 안전관리 리스크 평가 모형

박지현(Jihyun Park),박창순(Changsoon Park),안선웅(Suneung Ahn) 한국산업경영시스템학회 2015 한국산업경영시스템학회 학술대회 Vol.2015 No.추계

The major issue in aircraft industry is aviation safety management because of demand improvement and advancement of the aircraft. This study is to assess the risks for aviation safety management using IRPN( importance-risk priority number) which is added to importance coefficient from RPN(risk priority number). In FMEA, RPN requires the factors like the occurrence (O), Severity (S), and Detection (D) of each failure mode to be precisely evaluated. Therefore, the severity and detection is derived by the value from FMEA of expert group based on the Fuzzy theory. The occurrence is calculated from the accident statistics of IATA(international air transport association) database. Particularly, this study introduces importance coefficient to prevent from RPN distortions. It is also derived from FMEA based on the Fuzzy theory. Finally, the critical ranking of risk factors according to I-RPN is compared with the existing research.

Multifunctional Bilayer Template for Near-Infrared-Sensitive Organic Solar Cells

Kim, Hyungchae,Park, Han Gyeol,Maeng, Min-Jae,Kang, Yu Ri,Park, Kyung Ryoul,Choi, Junho,Park, Yongsup,Kim, Young Dong,Kim, Changsoon American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.19

<P>For organic solar cells (OSCs) based on nonplanar phthalocyanines, it has previously been reported that a thin film composed of triclinic crystals with face-on (or flat-lying)-oriented molecules, typically obtained with a CuI template layer, is desired for optical absorption in the near-infrared (NIR) spectral region. However, this work demonstrates that for a PbPc−C<SUB>60</SUB> donor-acceptor pair, less face-on orientation with a broader orientation distribution obtained with a new template layer consisting of a ZnPc/CuI bilayer is more desirable in terms of solar cell efficiency than the face-on orientation. A NIR-sensitive PbPc−C<SUB>60</SUB> OSC employing this bilayer-templated PbPc film is found to increase the internal quantum efficiency (IQE) by 36% on average in the NIR spectral region compared to a device using a CuI-templated PbPc film. Analyses of the change in IQE using the exciton diffusion model and the entropy- and disorder-driven charge-separation model suggest that the improved IQE is attributed to the facilitated dissociation of charge-transfer excitons as well as the reduction in exciton quenching near the indium tin oxide surface.</P> [FIG OMISSION]</BR>