• Communications for Statistical Applications and Methods
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• 제27권2호
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• pp.241-254
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• 2020

This study proposes generalized models of joint latent class analysis (JLCA) for longitudinal data in two approaches, a JLCA with latent profile (JLCPA) and a JLCA with latent transition (JLTA). Our models reflect cross-sectional as well as longitudinal dependence among multiple latent classes and track multiple class-sequences over time. For the identifiability and meaningful inference, EM algorithm produces maximum-likelihood estimates under local independence assumptions. As an empirical analysis, we apply our models to track the joint patterns of adolescent depression and anxiety among US adolescents and show that both JLCPA and JLTA identify three adolescent emotional well-being subgroups. In addition, JLCPA classifies two representative profiles for these emotional well-being subgroups across time, and these profiles have different tendencies according to the parent-adolescent-relationship subgroups.

• 대한산업공학회지
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• 제14권2호
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• pp.115-129
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• 1988

This paper discusses an analytical method to derive the efficiency and the average storage level of an unreliable two-machine, two-stage automatic transfer line with interstage buffer storage. Extensive numerical experiments and simulations are also conducted to see the behavior of the system under the wide range of parameter values as well as various distributions.

• 한국심리학회지 : 문화 및 사회문제
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• 제24권2호
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• pp.193-220
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• 2018

이 연구는 웰빙 차원에서 역기능적인 종교성을 질적으로 분석하는 것을 목적으로 하였다. 질적 분석을 위한 대상자는 종교인(성직자) 6명과 신앙인 6명이었다. 종교인의 경우 개신교 목회자 3명, 불교 종교인 2명, 원불교 종교인 1명이었고, 신앙인의 경우는 개신교 신앙인 2명, 천주교 신앙인 2인, 불교 신앙인 2인이었다. 종교인 6명 중에 한 명이 여성(불교)이었으며, 신앙인 6명 중에는 3명이 여성이었다. 본 연구에서 목적을 성취하기 위해 이야기식 인터뷰 방식과 Giorgi가 제시한 현상학적 분석방법을 이용하였다. 참여자들의 진술을 분석한 결과 22개의 주제가 도출되었고, 그 주제를 바탕으로 중심의미를 파악한 결과 9개로 구분할 수 있었다. 중심의미로는 보상추구적 종교성, 권력지향적 종교성, 이기적 종교성, 맹목적 종교성, 비사회적 종교성, 비실천적 종교성, 무체험적 종교성, 정서문제성 종교성 및 인지문제성 종교성이 도출되었다. 도출된 주제와 중심의미를 바탕으로 척도개발과 같은 추후 연구와 신앙인의 정신건강 증진을 위한 전략을 논의하고 제언하였다.

• 한국방재학회 논문집
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• 제10권6호
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• pp.99-108
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• 2010

본 연구에서는 네 개의 도로가 서로 대칭으로 연결된 교차로 근처 및 내에서의 흐름 특성에 대한 수치적 분석을 수행하였으며, 적용된 수치모형은 2차원 well-balanced HLLC 유한체적모형이다. 모의 및 분석결과 본 연구에서 적용된 모형은 유입유량 및 수로경사 조건에 따라 도로 교차로에서 변화되는 복잡한 수면양상을 비교적 잘 모의하는 것으로 나타났다. 또한 도로 교차로 내에서의 시간적 및 공간적 수심변화와 두 개의 하류경계에서의 유출유량에 대한 모의결과는 측정결과와 비교적 잘 일치하였다.

• Asian Journal for Public Opinion Research
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• 제11권1호
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• pp.4-30
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• 2023

Previous research has empirically demonstrated the negative effects of social media use on young people's psychological well-being. Unlike most previous studies that focused on either Facebook or Instagram, this study comparatively examined the differences in upward comparison and its effects on self-esteem, life satisfaction, and depression between Facebook and Instagram. An analysis of survey data from 641 Korean college students, who reportedly use these two social media more actively than any other age group, found that college students experience more upward comparisons on Instagram than on Facebook. Upward comparisons on both Facebook and Instagram increased by college students' age and weekly usage time. Upward comparisons on Instagram increased by the additional factors of gender (females more than males) and number of "followings." Subsequently, the effects of upward comparison on psychological well-being were found to differ by social media platform. Upward comparisons were found to negatively impact all determinants of psychological well-being only on Instagram, but not on Facebook. The differences in upward comparison and its impact on young users' psychological well-being found in this study were discussed in terms of the different functional characteristics of the two social media platforms, which provides direction for further research needed to establish guidelines for healthy social media use by young people.

• 설비공학논문집
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• 제29권3호
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• pp.119-126
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• 2017

Recently, ground source heat pump systems are being used in buildings for cooling and heating to reduce greenhouse gas and save energy. However, ground source heat pump systems mainly use the vertical closed-loop geothermal system design rather than the open-loop geothermal system design. This is due to a lack of knowledge and few research feasibility studies. In this research, a dynamic thermal analysis numerical simulation based on a standard house model was conducted for an open-loop geothermal system. Based on heating load analysis results, the life cycle costs of a standard house using an open two-well geothermal system were analyzed and compared with a vertical closed-loop geothermal system, and a diesel boiler. As a result, it was found that using an open two-well geothermal system shows economic return on investment after three years.

• 한국전문물리치료학회지
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• 제22권3호
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• pp.61-70
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• 2015

To develop an effective and efficient measurement system for tracking changes of functional status across two measures, it is essential to integrate information and communicate scores across two measures. The lack of communication between two measures leads to score incompatibility. A potential solution would be the development of a crosswalk table between those measures. Prior to creating a crosswalk table, selecting common items between two measures is critical. By using the Oswestry low back pain disability questionnaire (Oswestry) and a short form measuring disability resulting from low back pain, item level statistics as well as differential item functioning (DIF) using the Rasch measurement were investigated. Eighty-two participants with known group validity were recruited. Based on the application of the Rasch measurement model, item difficulties across the two measures were logically and hierarchically ordered. Ceiling effects for both measures were detected, which were not be able to be effectively measured with the two measures. The DIF analysis across the two measures confirmed that five paired items were found to have DIF and five common items were selected for common items. Although five paired items function differently across the Oswestry and the short form, all items of both measures were well targeted study participants. The common items selected by the Rasch measurement model may be effective when creating a crosswalk table between the Oswestry and the short form.

• Smart Structures and Systems
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• 제15권1호
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• pp.57-80
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• 2015

Extended Kalman Filter (EKF) has been widely used for structural identification and damage detection. However, conventional EKF approaches require that external excitations are measured. Also, in the conventional EKF, unknown structural parameters are included as an augmented vector in forming the extended state vector. Hence the sizes of extended state vector and state equation are quite large, which suffers from not only large computational effort but also convergence problem for the identification of a large number of unknown parameters. Moreover, such approaches are not suitable for intelligent structural damage detection due to the limited computational power and storage capacities of smart sensors. In this paper, a two-stage and two-step algorithm is proposed for the identification of structural damage as well as unknown external excitations. In stage-one, structural state vector and unknown structural parameters are recursively estimated in a two-step Kalman estimator approach. Then, the unknown external excitations are estimated sequentially by least-squares estimation in stage-two. Therefore, the number of unknown variables to be estimated in each step is reduced and the identification of structural system and unknown excitation are conducted sequentially, which simplify the identification problem and reduces computational efforts significantly. Both numerical simulation examples and lab experimental tests are used to validate the proposed algorithm for the identification of structural damage as well as unknown excitations for structural health monitoring.

• 대한교통학회지
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• 제11권1호
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• pp.23-36
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• 1993

The two-lane, two-way highway simulation program(TWOPAS) is evaluated for Korean Highway Capacity Manual Study. TWOPAS program input variables, especially related vehicle performance, traffic flow relationship, car-following model and passing logic are examined and modified through the analysis results of our two-lane, two-way highway traffic characteristics. Simulation outputs with and without modification are compared with the field data. The results show that improved TWOPAS program(TWOPAS KI) is well suitable for simulating our two-lane, two-way highway condition.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제35권2호
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• pp.106-111
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• 2009

Bisphosphonates have been approved for Paget's disease, cancer-related hypercalcemia, bone involvement in multiple myeloma or solid tumors and osteoporosis. Although, underlying pathophysiological mechanisms remain unclear, it seems that bisphosphonates inhibit osteoclast precursor cells, modulate migratory and adhesive characteristics and induce apoptosis of osteoclasts. Furthermore impacts on angiogenesis, microenvironment and signal transduction between osteoclasts and osteoblasts. In this report, we present a case of oral bisphosphonates induced osteonecrosis of the mandible in a 84-year-old patient who received for two years. Two tapered screw vent implants(Zimmer, USA) were placed in the area of first and second molar. Two weeks later after crowns restored, some inflammatory signs and symptoms were observed on the second molar area. Sequestrum was formed and the sequestrum was removed with the implant. Frequent follow-up checks and oral hygiene maintenances were done and the first molar implant was restored. There is insufficient evidence suggests that duration of oral bisphosphonate therapy correlates with the development and severity of osteonecrosis. Therefore, dentists should not overlook the possibility of development of bisphosphonate induced osteonecrosis in patients who have taken oral forms of medication for less than three years.