• 한국터널지하공간학회 논문집
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• 제25권2호
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• pp.87-99
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• 2023

지반굴착은 필연적으로 인접지반의 지반변위를 유발시키며, 지반변위에 노출된 구조물 및 시설물들은 다양한 피해를 입을 수 있다. 따라서 굴착유발 인접구조물 및 시설물의 손상 및 피해를 최소화하기 위해서는 우선적으로 굴착으로 인해 발생하는 인접지반에서의 지반변위(침하 및 수평변위)를 예측하여야 한다. 흙막이 굴착 유발 지반변위 정보는 상대적으로 많이 존재하지만 원형 형태의 수직구 굴착에 대한 지반변위 정보는 충분치 않다. 본 연구에서는 수직구 굴착에 대한 사례분석 및 흙막이 굴착과의 비교를 통해서 수직구 굴착유발 인접지반 침하예측에 대한 정보를 제공하고자 한다. 본 연구를 통해서 수직구 굴착 시 침하관리 기준으로서 흙막이 굴착의 침하기준을 사용하는 것은 안전성 측면에서 보수적인 접근방법으로 판단되나 경제성 측면을 고려할 때 벽체의 과다설계를 초래할 수 있어 수직구 굴착에 대해 보다 합리적인 침하기준이 필요한 것으로 나타났다.

• Earthquakes and Structures
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• 제22권3호
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• pp.245-261
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• 2022

Key questions to researchers interested in nonlinear analysis of skeletal structures are whether the distributed plasticity approach - albeit computationally demanding - is more reliable than the concentrated plasticity to adequately capture the extent and severity of the inelastic response, and whether force-based formulation is more efficient than displacement-based formulation without compromising accuracy. The present research focusing on performance-based seismic response of mid-span concrete bridges provides a pilot holistic investigation opting for some hands-on answers. OpenSees software is considered adopting different modeling techniques, viz. distributed plasticity (through either displacement-based or force-based elements) and concentrated plasticity via beam-with-hinges elements. The pros and cons of each are discussed based on nonlinear pushover analysis results, and fragility curves generated for various performance levels relying on incremental dynamic analyses under real earthquake records. Among prime conclusions, distributed plasticity modeling albeit inherently not relying on prior knowledge of plastic hinge length still somewhat depends on such information to ensure accurate results. For instance, displacement-based and force-based approaches secure optimal accuracy when dividing, for the former, the member into sub-elements, and satisfying, for the latter, a distance between any two consecutive integration points, close to the expected plastic hinge length. On the other hand, using beam-with-hinges elements is computationally more efficient relative to the distributed plasticity, yet with acceptable accuracy provided the user has prior reasonable estimate of the anticipated plastic hinge length. Furthermore, when intrusive performance levels (viz. life safety or collapse) are of concern, concentrated plasticity via beam-with-hinges ensures conservative predicted capacity of investigated bridge systems.

• 한국병원경영학회지
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• 제28권2호
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• pp.44-65
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• 2023

Purposes: As super-aging population and low fertility rates are threatening the sustainability of the National Health Insurance funds, enhancing the efficiency of hospital management is paramount. In the past, studies analyzing the efficiencies of hospitals primarily made inter-hospital comparisons, but it is important to assess hospitals' internal efficiency and develop improvement measures in order to attain practical improvements in hospital efficiencies. The purpose of this study is to analyze the efficiencies of specialists by medical specialty in a hospital in order to provide foundational data for efficient hospital management. Methodology/Approach: We used the activity-based costing (ABC) data and hospital statistical data from one tertiary hospital in Seoul to analyze the efficiency of specialists by medical specialty. Efficiency was analyzed and compared among specialists using the data envelopment analysis developed by Charnes, Cooper, and Rhodes (DEA-CCR) model and the slacks-based measure (SBM) models. The input variables were labor cost, material cost, and operational expenses, and the output variables were the number of outpatients, number of inpatients, outpatient revenue, and inpatient revenue. Findings: First, there was a marked deviation in efficiency across specialists. Second, there was a marked deviation in efficiency across medical specialties. Third, there was little difference in efficiency according to the specialist's sex, age, and job position. Fourth, the SBM model produced more conservative results and better explained efficiency parameters than the CCR model. Practical Implications: The efficiency of a specialist was more influenced by their medical specialty than their personal characteristics, namely sex, age, and job position. Therefore, Further research is needed to analyze the efficiencies of each subspecialty and identify factors that contribute to the variations in efficiencies across medical specialties, such as clinical practices and fee structures.

• 의정연구
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• 제27권2호
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• pp.41-70
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• 2021

바이든 행정부의 동북아 정책은 트럼프 행정부의 정책과 어떤 면에서 유사하고 어떤 면에서 다를 것인가? 본 논문은 트럼프 행정부로부터 바이든 행정부로의 이행에 따라 미국의 동북아 정책에 다음과 같은 변화와 연속성이 나타날 것이라고 제시한다. 미국 외교의 전통적 원칙과 관행을 중시하는 바이든 행정부의 성향상, 트럼프 시기와는 달리 미국의 동북아 정책에 있어 높은 안정성과 예측 가능성이 예상된다. 강력한 대중 압박 정책은 바이든 행정부에서도 지속될 것이며, 이에 따라 미중 대립은 더욱 지속·심화될 것이다. 한편 북한에 대해 바이든 행정부는 파격적 '그랜드 바겐'을 시도한 트럼프와는 달리 보수적 상향식 접근법을 취할 것으로 예상되며, 북한 정권의 협상 의도 및 태도에 회의적 관점을 가지고 있어 극적인 북미관계 진전은 당분간 어려워 보인다. 한국과 일본에 대해 바이든은 트럼프와 달리 양국을 동맹으로 중시하고 존중하는 태도를 보일 것이나, 심화되는 미중 갈등 속에서 한일 양국이 중국 견제에 있어 더 큰 역할을 수행하길 요구할 가능성이 높다.

• Asia Marketing Journal
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• 제15권2호
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• pp.29-47
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• 2013

Distribution channel decisions involve long-term commitments with other firms that are very difficult to change or replace. In particular, marketing channel decisions in emerging markets are much more complicated due to unfamiliar conditions and problems such as lack of market data and distribution systems. Therefore, when a company considers changing or introducing a marketing channel in an area, it is much more difficult to judge its effectiveness in an emerging market than in a developed market. In this study, we investigate the development process of a new direct marketing channel of Hongfu Fertilizer Company (hereafter Hongfu), a medium-sized Chinese fertilizer manufacturer, and propose an approach to test the feasibility of this new marketing channel in the Chinese rural market. We measure the effectiveness of Hongfu's new marketing channel from two perspectives: i) from customers' perspective through direct responses of farmers, which showed that a new channel can increase the convenience and lower the purchasing costs for the farmers, and ii) from the company's perspective, by calculating the incremental profit of the company using the expansion factor (T/Q) method, which suggested that the execution of Hongfu's strategy to expand a new marketing channel will result in an increase in profits. The results of this study contribute to the development of a methodology to test the feasibility of a new direct marketing channel in the emerging markets such as the Chinese rural market. Traditional and indirect distribution channels in emerging markets are generally not very efficient and difficult to change. Especially, in emerging markets, like the Chinese rural market, the methods of testing channel feasibility must be different from that of developed markets. Considering market situations, market experiments can be more effective then systematic market surveys in testing channel feasibility in emerging markets. This study implies that managers must learn to cope with a transition from the traditional marketing channels in emerging markets. With the development in farmers' understanding of marketing concept, the transition from traditional marketing channel is unavoidable for all firms. Farmers in China are generally very conservative, however, their buying behaviors are changing. Therefore, fertilizer companies should try to adjust in accordance with farmers' demand characteristics that the efforts to meet the economic needs of farmers with new marketing channels as well as trust building are critical in the near future.

• Structural Monitoring and Maintenance
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• 제10권3호
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• pp.207-220
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• 2023

The safety of bridges are critical in our transportation infrastructure. Bridge design and analysis require complex structural analysis procedures to ensure their safety and stability. One common method is to calculate the maximum moment in the girders to determine the appropriate bridge section. Girder distribution factors (GDFs) provide a simpler approach for performing this analysis. A GDF is a ratio between the response of a single girder and the total response of all girders in the bridge. This paper explores the significance of GDFs in bridge analysis and design, including their importance in the evaluation of existing bridges. We utilized Bridge Weigh-in-motion (B-WIM) measurements of five simple supported girder bridge in Indonesia to develop a simple GDF provisions for the Indonesia's bridge design code. The B-WIM measurements enable us to know each girder strain as a response due to vehicle loading as the vehicle passes the bridge. The calculated GDF obtained from the B-WIM measurements were compared with the code-specified GDF and the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) bridge design specification. Our study found that the code specified GDF was adequate or conservative compared to the GDF obtained from the B-WIM measurements. The proposed GDF equation correlates well with the AASHTO LRFD bridge design specification. Developing appropriate provisions for GDFs in Indonesian bridge design codes can provides a practical solution for designing girder bridges in Indonesia, ensuring safety while allowing for easier calculations and assessments based on B-WIM measurements.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.132-140
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• 2024

In the event of a severe accident in Sodium Cooled Fast Reactors (SFR), the sodium combustion aerosols along with fission product aerosols would migrate to the environment through leak paths of the Reactor Containment Building (RCB) concrete wall under positive pressure. Understanding the characteristics of sodium aerosol transport through concrete leak paths is important as it governs the environmental source term. In this context, experiments are conducted to study the influence of various parameters like pressure, initial mass concentration, leak path diameter, humidity etc., on the transport and deposition of sodium aerosols in straight leak paths of concrete. The leak paths in concrete specimens are prepared by casting and the diameter of the leak path is measured using thermography technique. Aerosol transport experiments are conducted to measure the transported and plugged aerosol mass in the leak paths and corresponding plugging times. The values of differential pressure, aerosol concentration and relative humidity taken for the study are in the ranges 10-15 kPa, 0.65-3.04 g/m³ and 30-90% respectively. These observations are numerically simulated using 1-Dimensional transport equation. The simulated values are compared with the experimental results and reasonable agreement among them is observed. From the safety assessment view of reactor, the approach presented here is conservative as it is with straight leak paths.

• 벤처창업연구
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• 제19권1호
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• pp.23-31
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• 2024

본 연구는 정부 주도사업이 투자자의 투자의사 결정 준거점에 미치는 영향을 실증적으로 탐색한다. 전망이론과 인적자원 이론을 접목하여 창업자의 인적자원 요소들을 준거점으로 활용하였다. 정부 주도사업의 영향으로 인해 투자자의 준거점에 변화가 있는지 실증적으로 탐색하였으며, 정부가 주도하고 지원하는 사업에 대해 민간이 투자할 때 고려해야 할 점을 시사한다. 연구 자료는 2017년 5월부터 2022년 5월까지 한국판 뉴딜에 해당하는 기업 51개와 해당하지 않는 기업 49개를 조사했으며 창업자 과거 창업 경험, 기술 산업 경력 기간, 경영관리 경력 기간, 최종학력 교육연수, 그리고 최종 졸업학교의 명성을 준거점으로 측정하여 연구를 진행했다. 회귀분석 결과 졸업학교 명성이 정부 주도사업과 부(-)의 영향을 미치는 것으로 나타났으며, 투자자의 준거점이 변화되는 것을 확인하였다.

• 대한영상의학회지
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• 제84권4호
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• pp.835-845
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• 2023

골반 외상은 대부분 고에너지 손상을 동반하며, 이에 따른 치명률 및 사망률이 높은 편이다. 관련된 출혈은 대부분 골반내 정맥이 손상되거나 해면골이 골절되어 발생하고 혈종에 의해 안정화되지만, 10%-20%에서 동맥 출혈이 동반되며, 골반 용적이 증가된 상태에서 동맥 출혈이 지속된다면 이로 인한 사망률은 36%-54%까지 증가한다. 골반의 해부학적 구조상 다양하고 풍부한 혈관이 분포되어 있고, 골반 외상 환자 대부분이 많은 양의 혈종을 동반하기 때문에, 수술적 치료는 시야 확보의 어려움과 눌림 효과에 따른 지혈효과를 없애 출혈을 더 조장할 수 있어, 1차적으로 인터벤션 치료가 권고되고 있다. 또한 출혈의 위치가 대부분 골절된 부분이기 때문에 CT를 통해 시술 전 출혈 부위를 특정하여 빠른 시간 내에 출혈에 대한 색전술을 시행할 수 있다. 이처럼 올바른 진단과 치료를 동시에 할 수 있다는 장점으로 인해 골반 외상 환자에 있어 인터벤션 치료는 중추적인 역할을 담당하고 있다. 본 연구에서는 문헌고찰을 통해 골반 외상에 대한 올바른 진단 및 인터벤션 치료의 유용성과 고려 사항에 대해 알아보고자 한다.

• Journal of Chest Surgery
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• 제57권5호
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• pp.430-439
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• 2024

Background: This study investigated the incidence and clinical consequences of abnormal radiological and clinical findings during routinely performed 6-week outpatient visits in patients treated conservatively for multiple (3 or more) rib fractures. Methods: A retrospective analysis was conducted among patients with multiple rib fractures treated conservatively between 2018 and 2021 (Opvent database). The primary outcome was the incidence of abnormalities on chest X-ray (CXR) and their clinical consequences, which were categorized as requiring intervention or additional clinical/radiological examination. The secondary focus was the incidence of deviation from standard treatment in response to the findings (clinical or radiological) at the routine 6-week outpatient visit. Results: In total, 364 patients were included, of whom 246 had a 6-week visit with CXR. The median age was 57 years (interquartile range, 46-70 years) and the median Injury Severity Score was 17 (interquartile range, 13-22). Forty-six abnormalities (18.7%) were found on CXR. These abnormalities resulted in additional outpatient visits in 4 patients (1.5%) and in chest drain insertion in 2 (0.8%). Only 2 patients (0.8%) with an abnormality on CXR presented without symptoms. None of the 118 patients who had visits without CXR experienced problems. Conclusion: Routine 6-week outpatient visits for patients with conservatively treated multiple rib fractures infrequently revealed abnormalities requiring treatment modifications. It may be questioned whether the 6-week outpatient visit is even necessary. Instead, a more targeted approach could be adopted, providing follow-up to high-risk or high-demand patients only, or offering guidance on recognizing warning signs and providing aftercare through a smartphone application.