• Tuberculosis and Respiratory Diseases
• /
• v.43 no.4
• /
• pp.547-557
• /
• 1996

Background : An excessive accumulation of neutrophils in lung tissue has been known to play an important role in mediating the tissue injury among the adult respiratory distress syndrome, idiopathic pulmonary fibrosis and cystic fibrosis by releasing toxic oxygen radicals and proteolytic enzymes. Therefore, it is important to understand a possible mechanism of neutrophil accumulation in lung tissue. In many species, exposure to hyperoxic stimuli can cause changes of lung tissues very similar to human adult respiratory distress syndrome and neutrophils are also functioning as the main effector cells in hyperoxic lung injury. The purpose of the present study was to examine whether neutrophils function as a key effector cell and to study the nature of possible neutrophil chemotactic factors found in bronchoalveolar lavage fluid from the hyperoxia exposed rats. Methods : We exposed the rats to the more than 95% oxygen for 24, 48, 60 arid 72 hours and bronchoalveolar lavage(BAL) was performed. Neutrophil chemotactic activity was measured from the BAT- fluid of each experimental groups. We also evaluated the molecular weight of neutrophil chemotactic tractors using fast performance liquid chromatography and characterized the substances by dialyzer membrane and heat treatment. Results : 1) The neutrophil proportions in bronchoalveolar lavage fluid began to rise from 48 hours after oxygen exposure, and continued to be significantly increased with exposure times. 2) chemotactic index for neutrophils in lung lavages from rats exposed to hyperoxia was significantly higher in 48 hours group than in control group, and was significantly increased with exposure time. 3) No deaths occured until after 48 hours of exposure. However, mortality rates were increased to 33.3 % in 60 hours group and 81.3 % in 72 fours group. 4) Gel filtration using fast performance liquid chromatography disclosed two peaks of neutrophil chemotactic activity in molecular weight of 104,000 and 12,000 daltons. 5) Chemotactic indices of bronchoalveolar lavage fluid were significantly deceased when bronchoalveolar lavage fluid was treated with heat ($56^{\circ}C$ for 30 min or $100^{\circ}C$ for 10 min) or dialyzed (dialyzer membrane molecular weight cut off : 12,000 daltons). Conclusion : These results suggested that the generation of neutrophil chemotactic factor and subsequent neutrophil influx into the lungs are playing an important roles in hyperoxia-induced acute lung injury. Neutrophil chemotactic factor in the lung lavage fluids consisted of several distinct components having different molecular weight and different physical characteristics.

• Korean Journal of Remote Sensing
• /
• v.36 no.5_1
• /
• pp.847-860
• /
• 2020

The 2-pass DInSAR (Differential Interferometric SAR) processing steps for DEM generation consist of the co-registration of SAR image pair, interferogram generation, phase unwrapping, calculation of DEM errors, and geocoding, etc. It requires complicated steps, and the accuracy of data processing at each step affects the performance of the finally generated DEM. In this study, we developed an improved method for enhancing the performance of the DEM generation method based on the 2-pass DInSAR technique of TanDEM-X bistatic SAR images was developed. The developed DEM generation method is a method that can significantly reduce both the DEM error in the unwrapped phase image and that may occur during geocoding step. The performance analysis of the developed algorithm was performed by comparing the vertical accuracy (Root Mean Square Error, RMSE) between the existing method and the newly proposed method using the ground control point (GCP) generated from GPS survey. The vertical accuracy of the DInSAR-based DEM generated without correction for the unwrapped phase error and geocoding error is 39.617 m. However, the vertical accuracy of the DEM generated through the proposed method is 2.346 m. It was confirmed that the DEM accuracy was improved through the proposed correction method. Through the proposed 2-pass DInSAR-based DEM generation method, the SRTM DEM error observed by DInSAR was compensated for the SRTM 30 m DEM (vertical accuracy 5.567 m) used as a reference. Through this, it was possible to finally create a DEM with improved spatial resolution of about 5 times and vertical accuracy of about 2.4 times. In addition, the spatial resolution of the DEM generated through the proposed method was matched with the SRTM 30 m DEM and the TanDEM-X 90m DEM, and the vertical accuracy was compared. As a result, it was confirmed that the vertical accuracy was improved by about 1.7 and 1.6 times, respectively, and more accurate DEM generation was possible with the proposed method. If the method derived in this study is used to continuously update the DEM for regions with frequent morphological changes, it will be possible to update the DEM effectively in a short time at low cost.

• The Korean Journal of Nuclear Medicine
• /
• v.37 no.5
• /
• pp.278-287
• /
• 2003

Purpose: The performance of nitroglycerin-challenged Tc-99m-MIBI quantitative gated SPECT for the detection of viable myocardium was compared with rest/24-hour redistribution Tl-201 SPECT Materials and Methods: In 22 patients with coronary artery disease, rest Tl-20l/ dipyridamole stress Tc-99m-MIBI gated/24-hour redistribution Tl-201 SPECT were peformed, and gated SPECT was repeated on-site after sublingual administration of nitroglycerin (0.6 mg). Follow-up gated SPECT was done 3 months after coronary artery bypass graft surgery. For 20 segments per patient, perfusion at rest and 24-hour redistribution, and wall motion and thickening at baseline and nitroglycerin-challenged state were quantified. Quantitative viability markers were evaluated and compared;(1) rest thallium uptake, (2) thallium uptake on 24-hour redistribution SPECT, (3) systolic wall thickening at baseline, and (4) systolic wall thickening with nitroglycerin-challenge. Results: Among 100 revascularized dysfunctional segments, wall motion improved in 66 segments (66%) on follow-up gated myocardial SPECT after bypass surgery. On receiver operating characteristic (ROC) curve analysis, the sensitivity and specificity of rest and 24-hour delayed redistribution Tl-201 SPECT were 79%, 44% and 82%, 44%, respectively, at the optimal cutoff value of 50% of Tl-201 uptake. The sensitivity and specificity of systolic wall thickening at baseline and nitroglycerin-challenge were 49%, 50% and 64%, 65% at the optimal cutoff value of 15% of systolic wall thickening. Area under the ROC curve of nitroglycerin-challenged systolic wall thickening was significantly larger than that of baseline systolic wall thickening (p=0.004). Conclusion: Nitroglycerin-challenged quantitative gated Tc-99m-MIBI SPECT was a useful method for predicting functional recovery of dysfunctional myocardium.

• Journal of the Society of Disaster Information
• /
• v.11 no.1
• /
• pp.135-147
• /
• 2015

Recent underground common utility tunnels are underground facilities for jointly accommodating more than 2 kinds of air-conditioning and heating facilities, vacuum dust collector, information processing cables as well as electricity, telecommunications, waterworks, city gas, sewerage system required when citizens live their daily lives and facilities responsible for the central function of the country but it is difficult to cope with fire accidents quickly and hard to enter into common utility tunnels to extinguish a fire due to toxic gases and smoke generated when various cables are burnt. Thus, in the event of a fire, not only the nerve center of the country is paralyzed such as significant property damage and loss of communication etc. but citizen inconveniences are caused. Therefore, noticing that most fires break out by a short circuit due to electrical works and degradation contact due to combustible cables as the main causes of fires in domestic and foreign common utility tunnels fire cases that have occurred so far, the purpose of this paper is to scientifically analyze the behavior of a fire by producing the model of actual common utility tunnels and reproducing the fire. A fire experiment was conducted in a state that line type fixed temperature detector, fire door, connection deluge set and ventilation equipment are installed in underground common utility tunnels and transmission power distribution cables are coated with fire proof paints in a certain section and heating pipes are fire proof covered. As a result, in the case of Type II, the maximum temperature was measured as $932^{\circ}C$ and line type fixed temperature detector displayed the fire location exactly in the receiver at a constant temperature. And transmission power distribution cables painted with fire proof paints in a certain section, the case of Type III, were found not to be fire resistant and fire proof covered heating pipes to be fire resistant for about 30 minutes. Also, fire simulation was carried out by entering fire load during a real fire test and as a result, the maximum temperature is $943^{\circ}C$, almost identical with $932^{\circ}C$ during a real fire test. Therefore, it is considered that fire behaviour can be predicted by conducting fire simulation only with common utility tunnels fire load and result values of heat release rate, height of the smoke layer, concentration of O2, CO, CO2 etc. obtained by simulation are determined to be applied as the values during a real fire experiment. In the future, it is expected that more reliable information on domestic underground common utility tunnels fire accidents can be provided and it will contribute to construction and maintenance repair effectively and systematically by analyzing and accumulating experimental data on domestic underground common utility tunnels fire accidents built in this study and fire cases continuously every year and complementing laws and regulations and administration manuals etc.

• Journal of Intelligence and Information Systems
• /
• v.26 no.2
• /
• pp.43-56
• /
• 2020

Recommender systems help users make the best choice among various options. Especially, recommender systems play important roles in internet sites as digital information is generated innumerable every second. Many studies on recommender systems have focused on an accurate recommendation. However, there are some problems to overcome in order for the recommendation system to be commercially successful. First, there is a lack of transparency in the recommender system. That is, users cannot know why products are recommended. Second, the recommender system cannot immediately reflect changes in user preferences. That is, although the preference of the user's product changes over time, the recommender system must rebuild the model to reflect the user's preference. Therefore, in this study, we proposed a recommendation methodology using topic modeling and sequential association rule mining to solve these problems from review data. Product reviews provide useful information for recommendations because product reviews include not only rating of the product but also various contents such as user experiences and emotional state. So, reviews imply user preference for the product. So, topic modeling is useful for explaining why items are recommended to users. In addition, sequential association rule mining is useful for identifying changes in user preferences. The proposed methodology is largely divided into two phases. The first phase is to create user profile based on topic modeling. After extracting topics from user reviews on products, user profile on topics is created. The second phase is to recommend products using sequential rules that appear in buying behaviors of users as time passes. The buying behaviors are derived from a change in the topic of each user. A collaborative filtering-based recommendation system was developed as a benchmark system, and we compared the performance of the proposed methodology with that of the collaborative filtering-based recommendation system using Amazon's review dataset. As evaluation metrics, accuracy, recall, precision, and F1 were used. For topic modeling, collapsed Gibbs sampling was conducted. And we extracted 15 topics. Looking at the main topics, topic 1, top 3, topic 4, topic 7, topic 9, topic 13, topic 14 are related to "comedy shows", "high-teen drama series", "crime investigation drama", "horror theme", "British drama", "medical drama", "science fiction drama", respectively. As a result of comparative analysis, the proposed methodology outperformed the collaborative filtering-based recommendation system. From the results, we found that the time just prior to the recommendation was very important for inferring changes in user preference. Therefore, the proposed methodology not only can secure the transparency of the recommender system but also can reflect the user's preferences that change over time. However, the proposed methodology has some limitations. The proposed methodology cannot recommend product elaborately if the number of products included in the topic is large. In addition, the number of sequential patterns is small because the number of topics is too small. Therefore, future research needs to consider these limitations.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.24 no.1
• /
• pp.111-121
• /
• 2006

Recently, many studies have been performed to apply airborne LIDAR data to extracting urban models. In order to model efficiently the man-made objects which are the main components of these urban models, it is important to extract automatically planar patches from the set of the measured three-dimensional points. Although some research has been carried out for their automatic extraction, no method published yet is sufficiently satisfied in terms of the accuracy and completeness of the segmentation results and their computational efficiency. This study thus aimed to developing an efficient approach to automatic segmentation of planar patches from the three-dimensional points acquired by an airborne LIDAR system. The proposed method consists of establishing adjacency between three-dimensional points, grouping small number of points into seed patches, and growing the seed patches into surface patches. The core features of this method are to improve the segmentation results by employing the variable threshold value repeatedly updated through a statistical analysis during the patch growing process, and to achieve high computational efficiency using priority heaps and sequential least squares adjustment. The proposed method was applied to real LIDAR data to evaluate the performance. Using the proposed method, LIDAR data composed of huge number of three dimensional points can be converted into a set of surface patches which are more explicit and robust descriptions. This intermediate converting process can be effectively used to solve object recognition problems such as building extraction.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.5B
• /
• pp.942-955
• /
• 2000

This paper proposes enhanced designs of global service logic and information flow for the mass-call based IN service, which increase call completion rates and optimize the resource in joint wired and wireless networks. In order to hanve this logic implemented, we design a Dynamic Queue Manager(DQM) applied to the call queuing service feature in the Service Control Point(SCP). In order to apply this logic to wireless service subscribers as well as wired service subscribers, the service registration flags between the Home Location Register(HLR) and the SCP are managed to notify the DQM of the corresponding service subscribers’ mobility. Hence, we present a dynamic queue management mechanism, which dynamically manages the service group and the queue size based on M/M/c/K queueing model as the wireless subscribers roam the service groups due to their mobility characteristics. In order to determine the queue size allocated by the DQM, we simulator and analyze the relationship between the number of the subscriber’s terminals and the drop rate by considering the service increment rate. The appropriate waiting time in the queue as required is simulated according to the above relationship. Moreover, we design and implement the DQM that includes internal service logic interacting with SIBs(Service Independent building Blocks) and its data structure.

• Journal of Soil and Groundwater Environment
• /
• v.13 no.1
• /
• pp.32-42
• /
• 2008

A surfactant recovery and reuse process by selective adsorption with activated carbon was proposed to reduce surfactant cost in a soil washing process. Mathematical model simulation was performed for the whole process, which consists of soil washing, soil recovery, and soil re-washing. The optimal range of surfactant dosage was $6{\sim}10$-fold critical micelle concentration in soil. The efficiency of surfactant reuse process was decreased with increasing the dosage of activated carbon. Effectiveness factor for activated carbon significantly altered the efficiency of the reuse process unlike effectiveness factor for soil. Total requirement of surfactant was reduced to 20-30% with the reuse process compared to the conventional soil washing process. The contamination of wastewater after soil washing was reduced with the reuse process. This mathematical model can be used to estimate performance of the whole process of soil washing including surfactant recovery and to obtain optimal ranges of operating conditions without extra labor-intensive experimental works.

• Journal of the Korea Concrete Institute
• /
• v.20 no.1
• /
• pp.13-22
• /
• 2008

The initiation and growth processes of cyclic ice body in porous systems are affected by the thermo-physical and mass transport properties, as well as gradients of temperature and chemical potentials. Furthermore, the diffusivity of deicing chemicals shows significantly higher value under cyclic freeze-thaw conditions. Consequently, the disintegration of concrete structures is aggravated at marine environments, higher altitudes, and northern areas. However, the properties of cyclic freeze-thaw with crack growth and the deterioration by the accumulated damages are hard to identify in tests. In order to predict the accumulated damages by cyclic freeze-thaw, a regression analysis by the response surface method (RSM) is used. The important parameters for cyclic freeze-thawdeterioration of concrete structures, such as water to cement ratio, entrained air pores, and the number of cycles of freezing and thawing, are used to compose the limit state function. The regression equation fitted to the important deterioration criteria, such as accumulated plastic deformation, relative dynamic modulus, or equivalent plastic deformations, were used as the probabilistic evaluations of performance for the degraded structural resistance. The predicted results of relative dynamic modulus and residual strains after 300 cycles of freeze-thaw show very good agreements with the experimental results. The RSM result can be used to predict the probability of occurrence for designer specified critical values. Therefore, it is possible to evaluate the life cycle management of concrete structures considering the accumulated damages due to the cyclic freeze-thaw using the proposed prediction method.

• Journal of KIISE:Software and Applications
• /
• v.26 no.8
• /
• pp.974-987
• /
• 1999

이동 컴퓨팅 환경에서 자주 접근하는 데이터에 대한 캐싱은 무선 채널의 좁은 대역폭에서 경쟁을 줄일 수 있는 유용한 기술이다. 그러나, 트랜잭션 캐시 일관성을 지원하는 전통적인 클라이언트/서버 전략은 클라이언트와 서버간에 많은 양의 통신을 필요로 하기 때문에 이동 클라이언트/서버 컴퓨팅 환경에서는 적절하지 않다. 본 논문에서는 브로드캐스트-기반 캐시 무효화 정책을 사용하면서 트랜잭션 캐시 일관성을 지원하는 OCC-UTS (Optimistic Concurrency Control with Update TimeStamp) 프로토콜을 제안한다. 접근한 데이터에 대한 일관성 검사 및 완료 프로토콜은 캐시 무효화 과정의 내부 과정으로 완전 분산 형태로 효율적으로 구현되며, 일관성 체크의 대부분이 이동 클라이언트에서 수행된다. 또한, 분석 모델에 기반한 성능 비교를 통해, 본 논문에서 제안하는 OCC-UTS 프로토콜이 다른 경쟁 프로토콜보다 높은 트랜잭션 처리율을 얻으며, 데이터 항목을 자주 접근하면 할수록 지역 캐시를 사용하는 OCC-UTS 프로토콜이 더 효율적임을 보인다. 이동 클라이언트의 접속 단절에 대해서는 무효화 브로드캐스트 윈도우를 크게 하여 접속 단절에 적절히 대처할 수 있다.Abstract In a mobile computing environment, caching of frequently accessed data has been shown to be a useful technique for reducing contention on the narrow bandwidth of the wireless channels. However, the traditional client/server strategies for supporting transactional cache consistency that require extensive communications between a client and a server are not appropriate in a mobile client/server computing environment. In this paper, we propose a new protocol, called OCC-UTS (Optimisitic Concurrency Control with Update TimeStamp), to support transactional cache consistency in a mobile client/server computing environment by utilizing the broadcast-based solutions for the problem of invalidating caches. The consistency check on accessed data and the commitment protocol are implemented in a truly distributed fashion as an integral part of cache invalidation process, with most burden of consistency check being downloaded to mobile clients. Also, our experiments based on an analytical model substantiate the basic idea and study the performance characteristics. Experimental results show that OCC-UTS protocol without local cache outperforms other competitor protocol, and the more frequent a mobile client accesses data items the more efficient OCC-UTS protocol with local cache is. With respect to disconnection, the tolerance to disconnection is improved if the invalidation broadcast window size is extended.