• The Journal of Asian Finance, Economics and Business
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• 제8권5호
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• pp.913-921
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• 2021

The objective of the study is to investigate the impact of the COVID-19 pandemic on Saudi Arabia stock market. The study relied on the data of the daily closing stock market price index Tadawul All Share Index (TASI), and the number of daily cases infected with COVID-19 during the period from March 15, 2020, to August 10, 2020. The study employs the Vector Auto-Regressive (VAR) model, the Impulse Response Function (IRF) and Autoregressive Conditional Heteroscedasticity (ARCH) models. The results of the correlation matrix and the Impulse Response Function (IRF) show that stock market returns responded negatively to the growth in COVID-19 infected cases during the pandemic. The results of ARCH model confirmed the negative impact of COVID-19 pandemic on KSA stock market returns. The results also showed that the negative market reaction was strong during the early days of the COVID-19 pandemic. The study concluded that stock market in KSA responded quickly to the COVID-19 pandemic; the response varies over time according to the stage of the pandemic. However, the Saudi government's response time and size of the stimulus package have played an important role in alleviating the impacts of the COVID-19 pandemic on Saudi Arabia Stock Market.

• 조명전기설비학회논문지
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• 제17권6호
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• pp.119-126
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• 2003

본 논문에서는 압연공정에서 압연용 롤을 구동하는 속도 제어 계통의 계단 응답 특성에 대한 관리지표값들을 자동으로 산출하는 알고리즘을 제안한다. 잡음이 포함된 속도 응답 데이터에서 최대값이 2개 이상 존재할 수 있는 경우들을 세 가지 독립된 유형으로 분류하였다. 각 유형별로 적절한 최대 오버슈트 후보를 선택하는 방법을 제안하였으며, 선택된 최대 오버슈트 후보가 옳은 지를 점검할 수 있는 판정 알고리즘을 개발하였다. 두 가지 유형의 시험을 통해 제안된 알고리즘으로 최대 오버슈트의 크기와 위치를 잘 검출할 수 있음을 보였다.

• 한국경영과학회지
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• 제29권1호
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• pp.31-41
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• 2004

This study analyzes the structure of the variations In the domestic bank earnings and examines their dynamic features by estimating the short-run response and the long-run adjustment Process after the changes in financial market variables. A system of the equations for the bank stock price index and KOSPI is formulated to utilize the whole information in the market and simultaneously estimated to identify the relationships between the market variables and the bank earnings. Since the bank stock price is found to be responsive to changes in none of the market variables in the short run, while being relatively responsive to dollar exchange rate and business state, It implies that a good economic conditions and a stable foreign exchange rate should be maintained to Improve the level of the stock price In the long run. In addition, the dynamic structure of the responses of the bank stock price index and KOSPI to the initial changes in the market variable are compared and anlayzed. The response of the bank stock price appears to take much longer in adjusting to the long-run eouilibrium level than that of KOSPI. As a result, the cumulative response of the bank stock price index over time is found much bigger than that of HOSPI.

• 한국화재소방학회논문지
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• 제26권3호
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• pp.79-84
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• 2012

본 연구에서는 국내외 스프링클러헤드 감도시험 기준에 적용하고 있는 반응시간지수(RTI, Response Time Index)를 사용하여 대류항과 전도항 그리고 시간 변화량을 고려한 감열부의 열전달 현상을 해석적으로 분석하였다. 원형 실린더 형상을 갖는 감열부의 열적 특성을 분석하기 위해서 비제차 2차 편미분 형태의 에너지 방정식을 사용하여 감열부 표면의 온도가 일정하고 대칭(Symmetric)인 경계조건을 적용하여 시간 증가에 대한 감열부의 반지름 방향 온도분포를 구하였다. 그 결과 본 연구의 감열부 열적 특성에 관한 분석 기법은 스프링클러헤드의 감도시험 및 감열부의 설계를 위한 자료의 활용이 가능할 것으로 판단된다.

• 한국산업보건학회지
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• 제26권4호
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• pp.426-435
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• 2016

Objectives: The major objective of this study was to analyze stress response after a change to consecutive day shifts from day and night shifts in a motor assembly factory. Methods: Using a survey conducted by a labor union, we collected data on stress response index(SRI), lifestyle factors, work-family conflict and job stress before and after a shift system change. We analyzed the transition on the SRI among 222 workers. The cut-off point for the SRI was a T-score over 60. Results: The high risk stress response group was 20.3% of the population before the shift system change. After the shift system change it decreased to 11.3%. After the shift system change, social support improved, leisure time became more sufficient, work-family conflict declined, and sleep quality in the night shift week improved. In multivariable linear regression, among workers under 40 years old sleep quality on night shift, leisure time sufficiency, social support and work-family conflict contributed to the improvement of stress response. Among workers over 40, work-family conflict contributed to the improvement of stress response. Conclusions: The change to consecutive day shifts improved stress response and mediated with improved nighttime sleep, decreased work-family conflict, increased leisure time and improved work-family conflict.

• 정보처리학회논문지D
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• 제12D권2호
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• pp.233-246
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• 2005

멀티미디어 데이터를 위한 내용기반 검색 서비스의 속도를 증진하기 위해 다차원 색인 기법에 대한 연구가 활발하게 진행되고 있다. 다차원 색인 기법의 하나인 M-트리는 노드의 중심점과 객체간의 상대적 거리를 이용하여 색인을 구성하고, 검색 공간에 포함되는 객체를 액세스하는 기법으로서 노드들은 페이지 단위로 구성되며 하위 엔트리들을 포함할 수 있는 반경, 즉 유사도 거리에 의해 노드의 영역이 표현되어진다. 그러나 이와 같은 노드의 영역 표현에 있어서 노드 색인 공간의 중첩으로 인해 질의 시 검색해야 하는 노드수가 증가하고 이는 거리계산과 디스크 입출력의 횟수를 증가시킨다. 본 논문에서는 M-트리에서 문제가 되고 있는 노드 색인 공간 중첩을 최소화하는 노드 분할 정책을 제안한다. M-트리의 기존 분할 정책들과는 다르게 노드의 가상 중심점을 계산하여 라우팅 객체로 이용하여 노드 색인 공간의 중첩을 최소화하고 노드 안의 엔트리 재분배를 통해 노드의 색인 공간의 크기를 작게 유지하며 밀도 높은 노드를 구성하도록 한다. 실험으로부터 제안된 노드 분한 알고리즘이 라우팅 노드의 색인 공간의 반경을 작게 유지하며 결과적으로는 사용자 질의에 대해 개선된 응답 시간을 제공하는 것으로 판명되었다.

• 한국디지털정책학회:학술대회논문집
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• 한국디지털정책학회 2005년도 추계학술대회
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• pp.45-60
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• 2005

The purpose of this study is to classify customer by e-mailing responsiveness on time-series analysis and testify the effectiveness of grouping by ROI analysis. Response recency, response frequency and Activity(RFA) of e-mailing systems were adapted for Customer segmentations. ROI analysis were consisted of open, click-through, duration time, personalization, conversion rate and email loyalty index of email systems. Major findings are as follows: RFA analysis is used for customer segmentations that is fundamental process of e-CRM applications. Customer segmentations were loyal customer, odds customer, dormant customer, secession customer and observation customer by RFA grouping. Loyal customer group has high point in all ROI index compared to other groups. These results indicated that customer responsiveness of e-mailing systems were appropriate methods to grouping the customer with demographic variables. Therefore, effective e-mailing marketing strategy of e-Biz have suitable active DB and Behavior targeting is best approach to enforcing the target e-mailing marketing.

• 기술혁신학회지
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• 제7권3호
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• pp.681-709
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• 2004

The purpose of this study is to classify customers by e-mail responsiveness on time-series analysis and testify the effectiveness of grouping by ROI analysis. Response recency, response frequency and Activity(RFA) of e-mailing systems are adapted for Customer segmentations. ROI analysis are consisted of open, click-through, duration time, personalization, conversion rate and email loyalty index of email systems. Major findings are as follows: RFA analysis is used for customer segmentations that is fundamental process of e-CRM applications. Customers can be grouped into loyal customers, odds customers, dormant customers, secession customers, and observation customers by RFA grouping. Loyal customer group has high point in all ROI index compared to other groups. These results indicated that customer responsiveness of e-mail systems were appropriate methods to group the customer with demographic variables. Therefore, effective e-mail marketing strategy of e-Biz should have suitable active DB and Behavior targeting is best approach to enforce the target e-mail marketing.

• Structural Engineering and Mechanics
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• 제87권1호
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• pp.95-106
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• 2023

This paper investigates the dynamic response of a functionally graded material (FGM) coated half-plane excited by distributed time harmonic loading. Three types of typical distributed surface loads, including uniform load, Hertz load, and square-root singular load, are considered. The mass density and elastic modulus of the FGM coating are supposed to be described by the exponential function. The material damping is modelled by a linearly hysteretic damping which is expressed by a complex modulus in the time harmonic motion. Using Fourier integral transform technique and numerical integral method, the effects of the excitation frequency, gradient index, damping, and load type on the dynamic stresses and displacements are discussed.

• 한국의류학회지
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• 제32권1호
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• pp.157-165
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• 2008

Transient thermal response of five types of underwear(cotton jersey, wool jersey, nylon jersey, cotton mesh and polyester mesh) for a protective coverall is evaluated using a sweating thermal manikin. Experimental protocol for transient thermal response of the sweating thermal manikin was also proposed. As results, it was found that steady state thermal response from sweating thermal manikin was not sensitive enough to evaluate thermal comfort of the experimental garments. However, when half time is used as an index of the heat flux change in transient thermal response, difference was found among underwear materials. Half time of cotton was the shortest and heat transfer of cotton was the fastest followed by polyester mesh, cotton jersey, nylon jersey and wool jersey. Dynamic thermal response of wool underwear was quite different from that of cotton underwear. Wool shows quite less heat flow at the initial stage, however, moisture permeability of wool was higher than cotton at the later stage. It was difficult to distinguish surface temperature difference visually using thermogram taken right before the completion of dry and wet test in steady state thermal response.