• The Korean Journal of Pain
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• 제35권1호
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• pp.59-65
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• 2022

Background: There is still unmet need in treating neuropathic pain and increasing awareness regarding the use of drug combinations to increase the effectiveness of treatment and reduce adverse effects in patients with neuropathic pain. Methods: This study was performed to determine the individual and combined effects of pregabalin, tianeptine, and clopidogrel in a rat model of neuropathic pain. The model was created by ligation of the L5-L6 spinal nerve in male Sprague-Dawley rats; mechanical allodynia was confirmed using von Frey filaments. Drugs were administered to the intrathecal space and mechanical allodynia was assessed; drug interactions were estimated by isobolographic or fixed-dose analyses. Results: Intrathecal pregabalin and tianeptine increased the mechanical withdrawal threshold in a dose-dependent manner, but intrathecal clopidogrel had little effect on the mechanical withdrawal threshold. An additive effect was noted between pregabalin and tianeptine, but not between pregabalin and clopidogrel. Conclusions: These findings suggest that intrathecal coadministration of pregabalin and tianeptine effectively attenuated mechanical allodynia in the rat model of neuropathic pain. Thus, pregabalin plus tianeptine may be a valid option to enhance the efficacy of neuropathic pain treatment.

• Structural Engineering and Mechanics
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• 제91권1호
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• pp.103-121
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• 2024

The smoothed particle hydrodynamics (SPH) method is a numerical technique used in dynamic analysis to simulate the fluid-like behavior of materials under extreme conditions, such as those encountered in explosions or high velocity impacts. In SPH, fluid or solid materials are discretized into particles. These particles interact with each other based on certain smoothing kernels, allowing the simulation of fluid flows and predict the response of solid materials to shock waves, like deformation, cracking or failure. One of the main advantages of SPH is its ability to simulate these phenomena without a fixed grid, making it particularly suitable for analyzing complex geometries. In this study, the structural damage to a masonry arch bridge subjected to blast loading was investigated. A high-fidelity micro-model was created and the explosives were modeled using the SPH approach. The Johnson-Holmquist II damage model and the Mohr-Coulomb material model were considered to evaluate the masonry and backfill properties. Consistent with the principles of the JH-II model, the authors developed a VUMAT code. The explosive charges (50 kg, 168 kg, 425 kg and 1000 kg) were placed in close proximity to the deck and pier of a bridge. The results showed that the 50 kg charges, which could have been placed near the pier by a terrorist, had only a limited effect on the piers. Instead, this charge caused a vertical displacement of the deck due to the confinement effect. Conversely, a 1000 kg TNT charge placed 100 cm above the deck caused significant damage to the bridge.

• 한국물환경학회지
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• 제18권4호
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• pp.379-386
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• 2002

In this study, estimation model for iron compound originated from upflow, anaerobic fixed bed reactor, which treats sewage domestic wastewater, was developed. The estimation model was formulated by a mathematical expression which was based on the mass balance. Below the HRT of 60 minute, sulfide concentration combining with iron $FeS_2$ is the highest because the maximum sulfate consumption rate $V_{maxS}$ and half-saturation constant of sulfate $K_{mS}$ exert an important effect on the estimation model as temperature was increased. But increment of $FeS_2$ concentration is weakened above the HRT of 60 minutes and represent the lowest value at the HRT of 108 minutes. It implies that liquid phase distribution ratio of sulfide ${\alpha}r$ becomes lower as temperature was increased. While phosphorus concentration combining with iron $Fe_3(PO_4)_3$ is increased as HRT and temperature are increased, which is affected by phosphorus removal rate constant $k_p$. As the result of estimating the iron concentrations of corrosion by the model, the concentration of iron corrosion is higher than any other at the HRT of 108 minute and $20^{\circ}C$. The predicted values were compared with measured ones at different HRT(13.5, 27, 54, 108 min) and temperature(20, 25, $30^{\circ}C$). The experimental data could be fitted with the simulated curves. Therefore, the mathematical expression could be applicable to design full-scale wastewater treatment plants.

• 디지털융복합연구
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• 제10권11호
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• pp.403-418
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• 2012

본 논문에서는 IT와 서비스 산업의 디지털융합 모델의 가치 창출요소의 시너지 효과를 이론적으로 정형화하고 실증분석을 통하여 시사점을 도출하였다. 경영전략 분야의 상황적합 이론에 기반 하여 IT융합의 근원적 가치요소를 고정형, 이동형으로 구분하고 이들 가치의 전략적 적합과 서비스 프로세스 제약완화 기여 등을 시너지 효과에 초점을 맞추어 탐색하였다. 본 논문에서 도출된 융합 시너지 연구 모델은 실증분석을 통하여 계층적 회귀분석 방법을 통하여 검증하였으며, 분석 결과 융합 모델의 가치 창출 요소의 유용성은 산업 별로 확연하게 구분되며 혁신에 의한 상대적 이점과 함께 일상생활 습관과의 부합성이 채택의 중요한 영향을 미치는 것이 발견되었다. IPTV 등에 기반 한 고정형 가치와 스마트 폰 등 모바일 기반 응용에 대한 시너지 효과와 프로세스 제약완화 등에 대한 시너지 효과가 제한적으로 나타났으며 이는 이들 가치가 서로 독립적으로 존재하며 융합 산업의 고유 특성과의 조화가 핵심적이라는 시사점이 도출되었다. 본 연구 결과는 향후 IT기반 산업 융합 모델 비즈니스 모델 연구에 유용한 시사점을 제공한다.

• KDI Journal of Economic Policy
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• 제41권1호
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• pp.1-14
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• 2019

This paper studies whether export diversification mitigated the negative effect of the global financial crisis on exports using the Korean case. Specifically, we use annual data on the exports of 24 Korean manufacturing industries from 2000 to 2016 and examine whether the negative effect of the crisis on exports was less prevalent in industries that were more diversified in terms of country and product. We also examine whether export competitiveness, as measured by the revealed comparative advantage index by industry, had a mitigating effect on trade during the crisis. In order to study these issues, we use panel regression with a fixed-effect model for 24 Korean manufacturing industries. From our empirical analysis, we find that country diversification weakened the negative impact of the global financial crisis on Korea's exports, whereas neither product diversification nor export competitiveness did so.

• Asian Journal of Business Environment
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• 제12권3호
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• pp.23-30
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• 2022

Purpose: This study aims to determine the effect of broadband access, education level, population numbers, and investment on the unemployment rate in Indonesia. Research design, data, and methodology: This study uses panel data from 34 provinces from 2016 to 2019. The analysis uses the fixed-effect model for panel data with the Feasible Generalized Least Square (FGLS) estimation method. Results: Broadband access has a negative and significant effect on the unemployment rate. Mean years of school, population, and foreign direct investment also have a negative and significant impact on the unemployment rate. In contrast, the domestic direct investment variable has a positive and significant effect. Conclusion: The availability of broadband access in an area allows easier and faster access to information. The ease of access to such information can affect producing goods and services, encouraging innovation and employment growth, and reducing the unemployment rate. This research recommends that the government intensify the Indonesia Broadband Plan policy to accelerate the development and equitable distribution of broadband access in all regions of Indonesia.

• 제어로봇시스템학회논문지
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• 제6권3호
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• pp.241-247
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• 2000

The reference model of an MRC (model reference control) provides the desired trajectory a plant should follow and thus the design of a reference model has a significant effect on control performance. In most control systems control input to a plant has some bounds and it is preferable to make use of as large control inputs as possible within the range of no saturation. In this paper a new approach of selecting the reference model is proposed for bounded control inputs. Design variables of the reference model are determined in such a way that maximizes the performance index within the range of no saturation. Moreover this variable reference model is regularly updated during control. This scheme is verified by application to the servo motor position control system in various simulations. The responses of the MRC with a variable reference model show better tracking performance than that with a fixed reference mode. Moreover by adjusting the update interval of the reference model the control performance can be further improved.

• 산업노동연구
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• 제24권2호
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• pp.181-214
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• 2018

본 연구는 한국고용정보원의 청년패널조사(YP2007 2~9차) 자료를 이용하여 청년층 노동시장에서 발생되는 주관적 미스매치의 현상을 살펴보고, 주관적 미스매치의 결정요인 및 임금효과를 분석하였다. 분석 결과, 전반적으로 학력과 기술 수준 모두 미스매치 중 학력과잉과 기술과잉은 두드러지게 감소하는 것으로, 학력부족과 기술부족은 다소 완만하게 증가하는 추이를 보였다. 다음으로, 하향취업(학력/기술 과잉) 결정요인에 대한 분석 결과, 남성은 여성에 비해 하향취업(학력/기술 과잉)이 될 가능성이 낮았으며, 종사상 지위에서는 임시/일용직 보다 상용직 및 비임금근로자의 하향취업 확률이 낮게 나타났다. 마지막으로 pooled OLS 모형과 패널고정효과 모형으로 미스매치의 임금효과를 추정한 결과, 임금에 가장 큰 영향을 미치는 미스매치는 학력과잉인 것으로 나타났고, 학력과잉인 청년취업자들은 그렇지 않은 집단(적정학력)에 비해 평균적으로 6.7% 낮은 임금을 받고 있는 것으로 추정되었다. 관찰되지 않은 개별의 특성을 통제한 후에도 3.2%의 낮은 임금을 받는 것으로 나타났으며, 기술과잉 미스매치의 경우 2.9%, 전공 미스매치가 2.3%로 기준집단에 비해 낮은 임금을 받고 있는 것으로 추정되었다.

• Journal of the Korean Data and Information Science Society
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• 제23권6호
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• pp.1103-1115
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• 2012

본 연구는 고지혈증에 대해 양파추출물을 투여한 무작위 대조군 전-후 실험설계 연구 12편을 대상으로 체중, 간 무게, 신장 무게, 심장 무게, 혈당, 총콜레스테롤, 트리글리세리드, HDL-콜레스테롤, LDL-콜레스테롤의 평균비교를 통해 양파의 효능에 대해 알아보았다. 고정효과모형을 적용시킨 결과 체중과 심장 무게를 제외한 간 무게, 신장 무게, 혈당, 총콜레스테롤 농도, 트리글리세리드 농도, LDL-콜레스테롤 농도는 유의한 감소를 보였고, HDL-콜레스테롤 농도는 유의하게 증가하였다. 갈브레스 그림으로 동질성 여부를 알아보았고 동질성을 만족하지 않은 변수에 대해 랜덤효과모형을 적용시킨 결과 간 무게와 혈당, 총 콜레스테롤 농도, 트리글리세리드 농도의 감소에 대해 유의한 효과를 나타냈고, HDL-콜레스테롤 농도는 유의하게 증가하였다. 각 변수에 대해 출판편의의 존재를 알아보았고, 출판편의의 존재를 확인 후 절단과 보충 방법으로 대체값을 추정하였다.

• 산경연구논집
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• 제12권8호
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• pp.7-19
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• 2021

Purpose: This paper aims to investigate (1) whether the interviewed auditors conduct higher quality audit than the non-interviewed auditors and (2) whether the frequency of audit engagement interviews has an impact on audit quality. Research design, data, and methodology: Using a sample of Chinese A-share listed firms between 2011 and 2019, this paper empirically tests the effect of audit engagement interviews on auditor's behavior. We collect the data of audit engagement interviews on the CICPA's website. We use OLS regression, fixed-effect model and random-effect model to examine the association between audit engagement interviews and audit quality. Results: Findings indicate that the audit quality of the interviewed auditors is significantly greater than that of the non-interviewed auditors. The frequency of the audit engagement interviews is positively associated with audit quality. The interviewed auditors spend significantly more time on the audit. Furthermore, the positive association between audit engagement interviews and audit quality only exists in non-Big 4 auditors. Conclusions: Our findings provide evidence for the effectiveness of audit regulation enforcement. The results suggest that in an emerging market with weak legal systems, preventive regulations such as audit interviews have a deterrent effect and are necessary in alleviating information asymmetry and improving information environment.