• Journal of Software Engineering Society
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• v.27 no.1
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• pp.8-14
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• 2018

As cloud computing has emerged as a hot trend in the IT industry, various types of cloud services have emerged. In addition, cloud service broker (CSB) technology has emerged to alleviate the complexity of the process of selecting the desired service that user wants among the various cloud services. One of the key features of the CSB is to recommend the best cloud services to users. In general, CSB can use a method to evaluate a service by receiving feedback about a service from users in order to recommend a cloud service. However, since each user has different criteria for giving a rating, there is a problem that reliability of service evaluation can be low when the rating is only used. In this paper, a method is proposed to supplement evaluation of rating based service by applying machine learning based sentiment analysis to cloud service user's review. In addition, the CSB prototype is implemented based on proposed method. Further, the results of comparing the performance of various learning algorithms is proposed that can be used for sentiment analysis through experiments using actual cloud service review as learning data. The proposed service evaluation method complements the disadvantages of the existing rating-based service evaluation and can reflect the service quality in terms of user experience.

• Journal of Internet Computing and Services
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• v.14 no.6
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• pp.85-94
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• 2013

With the emergence of world wide web, in particular web 2.0 the rapidly growing amount of news articles has created a problem for users in selection of news articles according to their requirements. To overcome this problem different clustering mechanism has been proposed to broadly categorize news articles. However these techniques are totally machine oriented techniques and lack users' participation in the process of decision making for membership of clustering. In order to overcome the issue of zero-participation in the process of clustering news articles in this paper we have proposed a framework for clustering news articles by combining users' judgments that they post on twitter with the news articles to cluster the objects. We have employed twitter hash-tags for this purpose. Furthermore we have computed the credibility of users' based on frequency of retweets for their tweets in order to enhance the accuracy of the clustering membership function. In order to test performance of proposed methodology, we performed experiments on tweets messages tweeted during general election 2013 in Pakistan. Our results proved over claim that using users' output better outcome can be achieved then ordinary clustering algorithms.

• Tunnel and Underground Space
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• v.23 no.4
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• pp.288-296
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• 2013

In this study, a total of 13 mines were finally selected as study subjects and field measurements were conducted. Thereafter, calculations of thermodynamic natural ventilation were attempted using spread sheets and solutions for natural ventilation of mine types with multiple vertical shafts were obtained. Based on the results, natural ventilation of each mine was quantified. In addition, changes in natural ventilation energy (NVE) and natural ventilation pressure (NVP) were estimated assuming mine deepening and the resultant values were applied to mine conditions to observe changes in flow rates. Natural ventilation pressure in domestic mines is generally calculated to be in a range of 5 Pa~300 Pa. Although NVP increases as the depth increases, resistance also increases. Therefore, as the depth increases, flow rates show a tendency of converging on a certain value because of the relationship between NVP and mine resistance. Natural ventilation using shafts with depth differences is effective up to depths of 200~300 m. However, flow rate change rates resulting from NVP are small at depths deeper than approximately 200~300 m. Therefore, if a mine is deepened over 300 m, NVP will become insufficient and thus additional pressure obtained through mechanical ventilation will be necessary.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.25-30
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• 1992

최근 전자계산기를 이용한 진동해석 방법이 눈부시게 발달하여, 일반 구조물 이나 기계 구조물 등의 동특성을 설계 단계에서 정도 높게 예측하는 것이 가능하게 되었다. 그러나 종래의 구조해석은 주어진 시스템의 동특성을 위한 것으로 얻어진 동특성으로부터 질량, 관성제원 및 스프링상수값 등의 설계상 수값을 규명하는 연구는 미미한 실정이다. 이것에 대한 해결방법으로 크게 해석적인 방법과 실험적인 방법으로의 접근이 있어 왔다. 해석적인 방법으로 유한요소해석에서 얻은 모드좌표를 물리좌표로 변환하는 방법으로 Guyan의 정축소와 같은 절점축소를 행하는 방법이 고찰되었다. 실험적인 방법으로 가 진실험에서 얻은 전달함수나 모드파라미터로부터 [M], [K] 행렬을 결정하는 연구가 있었지만 어떤것도 질량, 스프링상수 등의 설계상수를 완전히 규명하 지는 못하였다. 또한, 설계 단계에서 필요한 질량, 관성제원 또는 스프링상수 등의 최적한 값이나, 원하는 시스템특성을 얻을 수 있는 설계상수의 적정한 폭을 구하는 연구는 설계자의 경험과 반복된 시행착오에 의존하는 실정이다. 감도해석은 이러한 문제점을 개선하는 수단으로 설계변수에 대한 동특성의 변화율을 구하는 것이다. 감도해석을 수행하는 것은 어느 설계변수를 수정하 는 것이 주어진 동특성에 부합되는 지를 알려주고, 어느 것을 수정하는 것이 원하는 방향의 동특성변화에 가장 효과적인지를 알려주는 것이다. 따라서 감 도해석을 이용하여 설계의 최적화 프로그램을 만들수 있고, 이것은 설계자가 요구하는 동특성을 목적함수로 하여 주어진 구조물을 최적화하는 설계상수 값을 얻을 수 있게 한다. 본 논문에서는 강체모델의 동특성으로부터 모델의 설계 상수를 규명하고, 동특성의 개선을 위하여 설계변수의 변경량을 물리좌 표계에서 얻는것을 목적으로 한다. 강체 마운트계의 관성제원 및 마운트강성 의 규명을 위하여 임으로 주어진 설계상수를 모델데이타로 하여 관성제원과 스프링 강성을 구하였다. 관성제원의 규명은 주어진 모델의 관성값을 모르는 것으로 하여 임의의 초기 관성값으로 감도해석에 의해 주어진 계의 관성값 을 물리 좌표계에서 규명하였다. 마운트 강성의 규명도 관성제원의 규명과 같은 방법으로 임의의 강성값으로 감도해석을 하여 강성값을 규명하였다. 또 한 감도해석에 의한 동특성 변경은 특정한 고유진동 수의 변경이 필요할 때, 고유진동수의 이동을 위한 관성제원의 변경 및 마운트 강성변경값을 예측할 수 있다. 본 연구수행의 기본적인 흐름도는 Fig.1.1과 같다. 위와 같은 작업 으로 엔진 마운트와 같은 강체 모델의 시스템 규명을 행하는 경우에 유한요 소해석 및 가진 실험으로 얻은 고유진동수의 정보 또는 원하는 고유진동수 의 특성을 기본으로 실제 설계에서 사용이 가능하도록 물리 좌표계에서 관 성 제원 및 스프링상수를 구할 수 있을 것이다.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.80-80
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• 2010

전자제품의 소형화, 경량화, 고집적화가 심화됨에 따라 전자제품을 구성하는 회로의 미세화 또한 요구되고 있다. 이러한 요구는 경성회로기판 (rigid printed circuit board, RPCB) 뿐만 아니라 연성회로기판 (flexible printed circuit board, FPCB) 에도 적용되고 있으며 이에 대한 많은 연구 또한 이루어지고 있다. 연성회로기판은 일반적으로 절연층을 이루는 폴리이미드 (polyimide, PI)와 전도층을 이루는 구리로 이루어져 있다. 폴리이미드는 뛰어난 열적 화학적 안정성, 우수한 기계적 특성, 연속공정이 가능한 장점을 가지고 있으나, 고온다습한 환경하에서 높은 흡습성으로 인해 전도층을 이루는 구리와의 접합특성이 저하되는 단점 또한 가지고 있다. 또한 전도층을 이루는 구리는 고온다습한 환경하에서 산화 발생이 용이하기 때문에 접합특성의 감소를 야기할 수 있다. 따라서 본 연구에서는 고온다습한 조건하에서 sputtering and plating 공정을 통해 순수 Cr seed layer를 가지는 연성회로기판의 seed layer의 두께와 시효시간의 변화로 인해 발생하는 접합특성의 변화를 관찰하고 분석하였다. 본 연구에서는 두께 $25{\mu}m$의 일본 Kadena사(社)에서 제작된 폴리이미드 상에 sputtering 공정을 통해 순수 Cr으로 이루어진 각각 두께 100, 200, $300{\AA}$의 seed layer를 형성한 후 전해도금법을 이용, 두께 $8{\mu}m$의 구리 전도층을 형성한 시료를 사용하였다. 제작된 시료는 고온다습한 환경하에서의 접합 특성의 변화를 관찰하기 위하여 $85^{\circ}C$/85%RH 항온항습 조건하에서 각각 24, 72, 120, 168시간 동안 시효처리 한 후, Interconnections Packaging Circuitry (IPC) 규격에 의거하여 접합강도를 측정하였다. 시료의 전도층은 폭 3.2mm 길이 230mm의 패턴을 가지도록, 절연층은 폭 10mm, 길이 230mm으로 구성되었으며 이를 50.8mm/min의 박리 속도로 각 시편당 8회의 $90^{\circ}$ peel test를 실시하였다. 파면의 형상과 화학적 조성을 분석하기 위해 SEM (Scanning electron microscope)과 EDS (Energy-dispersive X-ray spectroscopy)를 사용하였으며, 파면의 조도 측정을 위해 AFM (Atomic force microscope)을 사용하였다. 또한 계면의 화학적 결합상태를 분석하기 위해 XPS (X-ray photoelectron spectroscopy)를 통해 파면을 관찰 분석하였다.

• Fire Science and Engineering
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• v.23 no.4
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• pp.67-72
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• 2009

For the fire-fighting industry to advance, it is necessary to conduct research on which parts of the fire-fighting law should be changed from the system level, and to study the opinions of the fire-fighters whoa re working in the fire-fighting industry today, and to identify what needs to be changed. Moreover, it is necessary to become aware on the preventive measures to take to avoid fire so that the citizens can lead stable life. Design business among the fire-fighting facility business, it is the fire-fighting facility business that serves as the most basic when constructing building structure. This is an important legal matter that follows the fire-fighting business, fire-fighting audit business and even the maintenance and management business. This research sought to help the fire-fighting industry to contribute to the life of the general public and to increase welfare by identifying the problems pertaining to the fire-fighting facility design business among the fire-fighting industry so that the industry can become the fire-fighting industry that the citizens are interested in. Moreover, direction for advancement is proposed. As for the improvement measures for the fire-fighting policy pertaining to the fire-fighting facility design business, it is divided into the machinery and electricity fields in terms of the legal system pertaining to the general fire-fighting facility design business. Likewise, specialty in design is deficient. Thus, it should be integrated in a systematic level to contribute to the safety of the general public.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.6
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• pp.957-963
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• 2013

This study evaluated the quality characteristics of muffins prepared with different amounts (0%, 4%, 8%, or 12%) of apricot powder. The moisture content was higher in groups containing 8% and 12% apricot powder. The specific volume of muffins decreased as the amount of apricot powder increased. The lightness value was lower in groups containing apricot powder, with redness and yellowness values increasing with increasing amounts of apricot powder. Rheology tests showed no significant differences in hardness, springiness, and cohesiveness between control muffins and muffins with apricot added. Scanning electron microscopy showed that the number and size of air cells decreased with increasing levels of apricot powder. The substitution of wheat flour with apricot powder yielded muffins with a higher DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging activity and total polyphenol content. Consumer acceptance tests revealed no significant differences in appearance, smell, and texture between muffin samples, but the taste and overall acceptability scores were lowest for muffins with 12% apricot added. Therefore, up to 8% apricot powder can be incorporated into muffins to meet the sensory quality and functional needs of the consumer.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.501-514
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• 2015

Earthwork is a basic operation for all forms of civil works and affects construction time, cost and productivity. It is a mechanized operation that needs various construction equipment as a group and uses a lot of fuel for construction equipment. But, the problem is that earthwork operation is usually performed by equipment operator's heuristic and intuition, which can cause low productivity, high fuel consumption, and high carbon dioxide emission. As one of solutions for this problem, the fleet management system for construction equipment is suggested for effective earthwork planning, optimal equipment allocation, efficient machine operation, fast information exchange, and so forth. The purpose of this research is to suggest core methods for developing the equipment fleet management system. The methods include 3D solid parametric model generation, soil distribution using Cctree data structure, equipment fleet construction and equipment fleet operation. A simulation test is performed to verify the effectiveness of the equipment fleet management system in terms of equipment operating ratio, fuel usage, and $CO_2$ emission.

• Composites Research
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• v.27 no.6
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• pp.219-224
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• 2014

Nancomposites manufacture has been developed rapidly, because of reinforcing effects of CNT in terms of mechanical, electrical and thermal properties. In this study, 10 wt% CNT paste was fabricated with good dispersion state and easy processability. Damage sensing and reinforcing effect of CNT paste were investigated in nanocomposites. 10 wt% CNT paste exhibited better tensile and flexural properties than those of general 1 wt% CNT nanocomposites. To observe the healing effect of CNT paste, a crack was made artificially with 30wt% CF30wt%/PP composites, and the CNT paste was filled inside the crack. The damage sensing of CNT paste in CF30wt%/PP composites was investigated by electrical resistance measurement and mechanical tests. CNT paste exhibited good reinforcing effect in mechanical properties of CF30wt%/PP composites, and this reinforcing effect was getting better with larger cracks. The reason was because CNT paste had good interfacial adhesion with CF30wt%/PP composites to resist crack propagation. In electrical resistance measurement, there was a jump in electrical resistance signal at the adhesion interface. The jumping signal could be used to predict fracture of CF/PP composites. CNT nanocomposites for damage sensing had crack reducing effect and damage detection using electrical resistance method.

• Composites Research
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• v.31 no.4
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• pp.139-144
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• 2018

Long Fiber-reinforced composites have advantages of excellent production efficiency and formability of complex shapes compared to conventional continuous fiber reinforced composite materials. However, if we need to make complicated composite shapes or to assemble parts made of different materials, a variety of joining methods are needed. In general, long fiber prepreg sheet (LFPS) contains mold release agent to facilitate demolding after thermoforming. Therefore, mechanical fastening is required in addition to the adhesive bonding to get proper joining strength. In this study, we proposed a stainless steel insert for co-cure bonding which cures LFPS and bonds the stainless steel insert through thermoforming process. The wing of the insert which is spread during the thermoforming process induces adhesion and mechanical wedging effect and serves as a hook to resist the pulling force. The burn-out method was used to confirm the unfolded state of the stainless steel insert wings inserted into the composite material. The static pull-out test was performed to quantitatively evaluate the joining strength. From these experimental results, the condition which guarantees the most appropriate joining strength was derived.