• 한국대기환경학회지
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• 제27권3호
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• pp.272-280
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• 2011

A novel particle removal system for air handling unit (AHU) of subway station was evaluated experimentally. The novel system was designed in order to minimize the maintenance cost by applying axial-flow cyclones. The system consists of multiple cyclone units and dust trap. Based on our previous numerical study, it was found to be effective for removal $1\sim10{\mu}m$ sized dust particles. In this study, we manufactured the mock-up model and evaluated the model experimentally. Liquid and solid test particles were generated for evaluating collection efficiency of the system and the pressure drop was monitored. The collection efficiency was varied from 41.2% to 85.9% with increasing the sizes of particle from 1 to $6.5{\mu}m$ by particle count ratio of inlet and outlet. The pressure drop was maintained constant less than $20mmH_2O$. In addition, the collection efficiency was estimated by total mass for solid test particles. It was found that the collection efficiency was 65.7% by particle mass ratio of inlet and outlet. It shows that present system can replace current pre-filters used in subway HVAC system for removing particulate matters with minimal operational cost.

• 조명전기설비학회논문지
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• 제24권6호
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• pp.18-26
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• 2010

도시공간의 안정과 쾌적함을 위하여 옥외조명은 우리 사회에서 필수적인 부분이 되었다. 그러나 옥외조명을 잘못 설치할 경우 조명에너지의 낭비뿐만 아니라 건축물 야간경관 훼손을 야기시킨다. 최근 야간 경관조명의 중요성이 부각되면서 지자체마다 야간경관 이미지 구축에 집중을 하고 있다. 그 중 해안가 주변의 옥외조명은 지역 내에 특화된 관광 상권을 구성하며 생동감 있는 도시 이미지를 부여하고 도시경쟁력을 강화 시킬 수 있다. 본 연구는 우리나라의 대표적 항구 도시인 부산의 해안가의 야간경관조명의 빛공해를 평가하는데 그 목적이 있다. 디지털 광학 계측기인 Radiant Imaging ProMetric-1400으로 광안리 해수욕장, 마린시티, 그리고 해운대 해수욕장 주변의 옥외조명을 측정하였다. 모든 옥외조명의 휘도는 국제조명위원회 권고기준과 비교했을 때 약 2~20배 정도 높게 나타났다. 주상복합 상부조명 및 해안에 면한 상가 저층부는 색채 및 휘도의 제한이 필요한 것으로 사료된다.

• Journal of Welding and Joining
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• 제20권2호
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• pp.82-89
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• 2002

In order to clarify hot cracking phenomena occurred in Inconel 690 welds and it's prevention, in this study, the cracking behavior and the influence of welding variables on cracking in Inconel 690 overlay welds on Mn-Ni-Cr-Mo steel(SA 508 cl.3) for pressure vessel were investigated by using mock-up test. The main results are as follows: The cracks in Inconel 690 overlay welds were mainly generated near the start and the end part of welding beads adjacent to STS 309L welded outside of Inconel 690 welds. Most of the cracks showed typical solidification crack, and also it was assumed that there was possibility of liquation cracking in HAZ. The existence of Nb constituents or concentration of Nb was recognized on the fracture facets of the solidification cracks in the welds by SMAW. Therefore Nb was considered to be the main factor of the solidification cracking. As the weld heat input was more increased and the weld bead length was longer, the extent of cracking was more increased. Moreover the extent of cracking was considerably decreased by changing of welding sequence to the start and the end part of welds. Hot cracking in welds by GTAW was considerably decreased as compared with that of SMAW. And cracks were well generated in the Inconel 690 overlay welds adjacent to 575 309L welds. This means that the hot cracking susceptibility of Inconel 690 welds was largely varied by chemical components and/or compositions of filter metals, base metals and neighboring welds.

• International Journal of Aeronautical and Space Sciences
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• 제15권3호
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• pp.309-319
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• 2014

This paper mainly focuses on the conceptual design and stealth performance of the three-surface military aircraft. A three-dimensional (3-D) digital mock-up of the three-surface strike fighter with stealth feature was designed and the schemes of carrying missiles were analyzed in CATIA. Based on physical optics principle and the Method of Equivalent Currents (MEC), a numerical simulation of the RCS feature of the aircraft was carried out with RCSPlus which is a software designed by Beihang University. The paper contributes to the RCS feature analysis of the whole plane and different parts on X-band, S-band and UHF-band and a comparison of RCS feature to Su-37 and T-50 military aircraft is drawn. On X-band, the pitch angle of the incident wave was $0^{\circ}$, and the result shows: (1) Compared with Su-37 aircraft, the forward scattering RCS of the three-surface strike aircraft was reduced to 14.9%, the side scattering RCS to 9.6% and the back scattering RCS to 40.2%. (2) Compared with T-50 aircraft, the forward scattering RCS was reduced to 38.61%, and the side scattering RCS to 67.26%. This paper should be useful for researchers in conceptual design and stealth technology of the military aircraft.

• Asian Pacific Journal of Cancer Prevention
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• 제16권7호
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• pp.2883-2887
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• 2015

Background: The calcium-binding S100A4 protein is involved in epithelial to mesenchymal transition, oncogenic transformation, angiogenesis, cytoskeletal integrity, mobility and metastasis of cancer cells. This study aimed to clarify the roles of S100A4 in genesis and progression of glioma. Materials and Methods: S100A4 expression was examined by real-time RT-CPR and Western blot in glioma and paired normal brain tissue (n=69), and compared with clinicopathological parameters of tumors. In addition, glioma U251 cells transfected with an S100A4-expressing plasmid were examined for proliferation by MTT, apoptosis by Annexin V-FITC, and migration and invasion with Transwell chambers. Results: Increased S100A4 mRNA expression was found in gliomas, compared with paired non-tumor tissue (p<0.001). Gradual elevation of overexpression of S100A4 was observed with increasing glioma grade (p<0.001). Astrocytoma showed lower S100A4 mRNA expression than oligodendrogliomas, with glioblastomas having highest values (p<0.001). Similar results were obtained for S100A4 protein, a positive link being found between mRNA and protein expression in gliomas (p<0.001). There was higher growth, lower apoptosis, stronger migration and invasion of S100A4 transfectants than control and mock transfected cells (p<0.001). Conclusions: These findings indicate that up-regulated S100A4 expression is positively linked to pathogenesis, progression and histogenesis of glioma by modulating proliferation, apoptosis, migration and invasion.

• 한국자기학회지
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• 제20권3호
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• pp.100-105
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• 2010

본 논문에서는 강자성 선체에 존재하는 영구자화 분포에 기인한 자기장 신호를 예측하고자 연속체역학에 기반을 둔 매질민감도법과 등가 자기 모델을 결합한 역문제 해석 기법을 제시한다. 이를 위하여 3차원 자기전하 모델과 2차원의 등가 자기쌍극자 모델을 구축하였고 각각의 등가모델에 맞는 매질민감도 공식을 유도하였다. 매질민감도법은 자기전하나 자기쌍극자 변화에 대한 목적함수의 1차 미분정보를 제공하고 설계변수의 개수에 영향을 받지 않기 때문에 최적해를 빠른 시간에 도출할 수 있다. 제안된 해석 기법의 타당성을 검증하기 위해서 실험을 통해 측정된 자기장 신호와 각각 등가모델에 의한 역문제 해석을 통해 얻어진 예측치를 비교하였다.

• 한국강구조학회 논문집
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• 제21권4호
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• pp.413-420
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• 2009

일반적으로 대형 지붕구조나 초대형 보와 같은 대형 구조물을 양중하는 방법은 유압잭이 이용된다. 또한, 양중시 안전을 위하여 CCTV를 이용하여 각 포인트에 설치된 줄자를 모니터링하여 레벨체크를 수행하고, 상대 변위가 기설정된 한계를 벗어나면 유압잭을 정지하고 상대변위를 수동으로 조정한 후에 양중을 수행하였다. 그러나, 이러한 종래의 양중 방법은 CCTV를 육안으로 확인하여 레벨을 체크하기 때문에 정확도가 높지 않았고, 실시간 계측은 현실적으로 불가능하였다. 이러한 문제를 개선하기 위하여 자동추적형 토탈스테이션, 레이저 거리계, 데이터로거, 변형도게이지 등을 이용하여 대형 구조물 양중시 적용할 수 있는 계측-평가 시스템 구축하였다. 시스템을 구현하기 위한 프로그램 작성 후 실험실에서 시연을 통해 계측-평가 데이터의 정확성 및 활용 가능성을 평가하였으며, 안정적인 데이터 취득 및 연산을 통해 적용성이 검증되었다.

• Journal of Chest Surgery
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• 제28권6호
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• pp.542-548
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• 1995

The goal of this study is to develop an effective control system for cardiac output regulation based upon the preload and afterload conditions without any transducers and compliance chambers in the moving actuator type total artificial heart. Motor current waveforms during the actuator movement are used as an input to the automatic control algorithm. While the current waveform analysis is performed, the stroke length and velocity of the actuator are gradually increased up to the maximum pump output level. If the diastolic filling rate of either right or left pump begins to exceed the venous return, atrial collapse will occur. Since the diastolic suction acts as a load to the motor, this critical condition can be detected by analyzing the motor current waveforms. Every time this detection criterion is met, the control algorithm decreases the stroke velocity and length of the actuator step by step just below the critical detection level. Then, they start to increase. In this way the maximum pump output under given venous return can be achieved. Additionally the control algorithm provides some degree of afterload sensitivity. If the aortic pressure is detected to exceed 120 mmHg, the stroke length and velocity decrease in the same way as the response to the preload. Left-right pump output balance is maintained by proper adjustment of the asymmetry of the stroke angle. In the mock circulatory test, this control system worked well and there was a considerable range of stroke volume difference with adjustment of the asymmetry value. Two ovine experiments were performed. It was confirmed that the required cardiac output regulation according to the venous return could be achieved with adequate detection of diastolic function, at least in the in vivo short-term survival cases[2-3 days . We conclude that this control algorithm is a promising method to regulate cardiac output in the moving actuator type total artificial heart.

• 한국건축시공학회지
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• 제12권3호
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• pp.347-357
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• 2012

While it is generally possible to install curved panels manufactured in a factory within the permitted error range on an irregular surface frame of concrete or steel, it is difficult and expensive. Freeform architecture is thus designed and constructed differently from formal buildings. In order to more easily and inexpensively actualize freeform architecture, Building Information Modeling (hereinafter referred to as BIM) has recently been applied in the construction industry. However, the related research and case analyses are not sufficient to identify the implications and contributions of freeform buildings in future similar projects. Therefore, this research will study design and construction methods for freeform surfaces, particular the concrete surface frame of freeform buildings based on BIM, focused on the Tri-Bowl project. This study attempts to analyze the pros and cons of each method for the concrete surface frame of the Tri-Bowl, and then presents the lessons learned and implications related to the design and construction process of the freeform architecture. Several implications for design and construction of concrete surface frame of the freeform building, the Tri-Bowl, are found. The first is that manufacturing and installation of a curved concrete frame is precisely performed based on the exact numerical values of materials and installation made using BIM 3D technologies, such as CATIA and Rhino. The second is that close and continuous collaboration among the different participants in the construction of the Tri-Bowl allowed them to cope with virtual conditions. The third is that design and construction processes have changed, and high quality of the surface frame of a freeform building is required.

• KIEAE Journal
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• 제14권6호
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• pp.99-104
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• 2014

Recently supply of low energy house is increasing which can enhance energy efficiency and indoor environment comfort. Low energy house have to secure air tightness as well as thermal performance so house become high airtightness and inevitably need heat recovery ventilator to enhance indoor air quality. However, most of current ventilation systems are one-click, controlling the entire space so it causes increasing of heating load and fan power which makes it hard to save energy. Thus, Individual Control system is required which can achieve both enhancing indoor air quality and decreasing heating load and electric fan power. Thereby, in this study, we analyzed the correlation between ventilation and fan power through mock-up experiment and measured ventilation load under individual control system. As a result, under the condition of $24^{\circ}C$ of indoor temperature for 6 month(November to April) in Daejeon, ventilation load by fan speed was $10.9{\sim}19.6kWh/m^2{\cdot}a$ when operated 24 hours and $7.6{\sim}13.7kWh/m^2{\cdot}a$ when operated 12 hours in night time. In addition, it is possible to reduce at most 60% of ventilation load under the individual control system; measured ventilation load was $7.4kWh/m^2{\cdot}a$ when operated 24 hours, and $5.5kWh/m^2{\cdot}$ when operated 12 hours in night time.