• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.5
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• pp.737-751
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• 2023

The importance of digital forensics in the cloud environment is increasing as businesses and individuals move their data from On-premise to the cloud. Cloud data can be stored on various devices, including mobile devices and desktops, and encompasses a variety of user behavior artifacts, such as information generated from linked accounts and cloud services. However, there are limitations in securing and analyzing digital evidence due to environmental constraints of the cloud, such as distributed storage of data and lack of artifact linkage. One solution to address this is archiving services, and Google's Takeout is prime example. In this paper, user behavior data is analyzed for cloud forensics based on archiving data and necessary items are selected from an investigation perspective. Additionally, we propose the process of analyzing selectively collected data based on time information and utilizing web-based visualization to meaningfully assess artifact associations and multi-behaviors. Through this, we aim to demonstrate the value of utilizing archiving data in response to the increasing significance of evidence collection for cloud data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.1
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• pp.125-132
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• 2024

Optical satellite images are being used for national security and collection of information, and their utilization is increasing. However, it acquires low-quality images that are not suitable for the user's requirement due to weather conditions and time constraints. In this paper, a deep learning-based conversion of image and colorization model referring to high-resolution SAR images was created to simulate the occluded area with clouds of optical satellite images. The model was experimented according to the type of algorithm applied and input data, and each simulated images was compared and analyzed. In particular, the amount of pixel value information between the input black-and-white image and the SAR image was similarly constructed to overcome the problem caused by the relatively lack of color information. As a result of the experiment, the histogram distribution of the simulated image learned with the Gray-scale image and the high-resolution SAR image was relatively similar to the original image. In addition, the RMSE value was about 6.9827 and the PSNR value was about 31.3960 calculated for quantitative analysis.

• Environmental and Resource Economics Review
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• v.16 no.1
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• pp.27-63
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• 2007

Using the CGE model, this paper investigates economic impacts of a shortage in crude oil resulting from voluntary export restraints, OPEC's agreement of a cut in oil production, and/or a storing on speculation. Unlike most previous studies considering oil price as the unpredictable variable, this study constructs the model to determine the oil price endogenously under the condition of an insufficient supply of crude oil. According to IEA's extraordinary steps for a shortage of crude oil, we investigate an economic impact of 7~12% shortage below the level of business as usual. The results show that oil price soars by 17.3~33.5%, the rate of economic growth falls by 0.52~0.96%p, and the consumer price index(CPI) rises by 0.8~1.51%p. These results imply that increasing in 1%p of oil price results in decreasing in 0.03%p of economic growth and increasing in 0.045%p of consumer price index. The production of electricity declines because of the increase in production cost. A shortage of crude oil has an effect on sources of electricity. Most reduction in electricity generation occurs from the reduction in the thermal power generation which is highly dependent on crude oil. The shortage of crude oil causes demand for petroleum to significantly decline but demand for coal and heat to increase because of the substitution effect with petroleum. Demand for gas rise in the first year but falls from the second year.

• Journal of Korea Soil Environment Society
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• v.2 no.2
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• pp.9-24
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• 1997

Surfactant-aided in situ soil flushing has been proposed as an alternative for the expensive and time consuming 'pump and treat' technology in remediation of contaminated soil and groundwater Injected surfactants can effectively solubilize contaminants sorbed to the soil matrix or nonaqueous phase liquids(NAPLs) in residual saturation. The contaminants solubilized in groundwater are recovered and treated further. The theoretical background of the technology and the results of the field operations, mostly in the US. were summarized. In addition, the factors crucial to the successful application of the technology were discussed. Cost analyses and technical limitations in current applications were also discussed. In conclusion, it is likely that in situ surfactant flushing become a viable option for soil remediation in limited cases. Currently, further advances with respect to operation cost and to treatment efficiency are required for more extensive application of the technology. However, the current trends in soil remediation, specially the growing emphasis on risk based corrective action and natural attenuation, will increase the competitiveness of the technology. For example, removal of easily washable contaminants by short term soil flushing followed by long term monitoring and natural attenuation can greatly reduce the operation cost and time.

• The Journal of the Korea Contents Association
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• v.6 no.9
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• pp.98-107
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• 2006

By improving performance of mobile machine(3D engine, 3D accelerator chip set, etc) and developing wireless network technology, a demand for actual contents of users is being increased rapidly. But, there are some difficulties yet for the speedy development of actual contents because of the limitation of development resources that is dependent on each mobile device's different performance. In general, much of the animated character-creation work for mobile environment is still done manually by experienced animator with the method of key frame processing. However, it needs a lot of time and more costs for creating motion. Additionally, it is possible to cause a distortion of motion. In this paper, I solved the difficulties by using a optical motion capture system, it was able to acquire accurate motion data more easily and quickly, and then it was possible to make 3D dance contents efficiently. Also, I showed techniques of key reduction and controlling frame number for using huge amounts of motion capture data in mobile environment which requires less resources. In making 3D dance contents, using an optical motion capture system was verified that it was more efficient to make and use actual-reality contents by creating actual character motion and by decreasing processing time than existing method.

• Journal of KIISE:Databases
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• v.30 no.5
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• pp.476-493
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• 2003

Data broadcast is an effective data transmission method from a data base server to numerous mobile clients due to the restrictions on mobile environment such as low wireless communication bandwidth and energy shortage of mobile devices. There are various broadcast methods based on clients' data access frequencies or semantic relationship of data. The broadcast schedule based only on the access frequencies does not consider semantic relations of data, so that when a client needs to access a series of semantically related data, the client has to listen to the wireless channel for a long time. On the other hand, the broadcast schedule based only on semantic relationship of data makes data access time longer when clients highly request specific data which are not semantically related but frequently accessed. In this paper, we present an efficient data broadcast method based on not only data access frequencies but also semantic relationship to improve mobile clients' query response time. The new hybrid broadcast method we propose creates a data broadcast schedule according to the data access frequencies and then the schedule is adjusted to reflect semantic relationship of data. We show our method is efficient by experimental performance analysis.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.6
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• pp.738-747
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• 1999

본 논문에서는 분산 실시간 시스템의 특징인 분산 처리 과정의 신뢰성을 지원하기 위한 동적 트랜잭션 처리 구조를 연구하였다. 실시간 분산 처리 환경에서 동적으로 발생하는 실시간 분산 트랜잭션 처리를 위하여 트랜잭션 내에 필수적인 3가지 언어적 특성들을 제시하였다. 첫째는 트랜잭션 내에 실시간 시스템의 가장 중요한 특징인 시간적인 제약 조건들을 정의 할 수 있는 방안을 제시하고, 둘째는 비동기적인 처리 성격을 지닌 실시간 특성을 고려한 비동기적 트랜잭션 처리 방법을 제시한다. 또한, 분산 처리 과정에서 발생되는 예외 사항들을 처리하기 위하여 긴급성을 고려한 다중레벨 우선순위 스케줄링 (Multi-Level Priotiry Scheduling)이라 부르는 트랜잭션 스케줄링 방안을 제시한다. 그리고, 제시한 실시간 분산 트랜잭션 처리 구조의 타당성 및 가능성을 입증하기 위한 실시간 트랜잭션 처리 과정을 시물레이션을 통하여 제시한 언어적 특성에 대한 고려 사항들을 보여준다.Abstract We propose a dynamic transaction processing model that supports a reliability for distributed real-time processing. For the dynamic processing in distributed real-time transaction systems, we suggest three features that are defined in programming language. First, we propose a specification model to explicitly define the time constraints, needs in real-time distributed processing. Second, we describe an asynchronous transaction processing mechanism based on the real-time characteristics. So, we suggest three communication primitives to support asynchronous transaction processing. Lastly, a scheduling policy based on urgent transaction is suggested to manage the exception occurred during the distributed processing. This scheduling policy is called multi-level priotiry scheduling (MPLS). Based on three features and scheduling policy, we describe a direction to manage a dynamic transaction processing in distributed real-time systems.

• The KIPS Transactions:PartC
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• v.17C no.6
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• pp.471-484
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• 2010

In the wireless communication systems, the power consumption of a mobile device is very important issue due to its battery limitations. Hence most of the standards for wireless networks including a mobile WiMAX system are supporting their own power saving mode in way that a mobile device is able to reduce its energy usage while in the mode. However, those standards just define the arrangement of special time intervals, called a paging listening interval, during which the device needs to receive the paging-related control messages, and they do not specify how to effectively reduce the power in many different network environments. This means the amount of power spent by the device is very dependent on the implementations of individual device-vendors, and undesirable paging loss may happen according to the channel conditions. To reduce unnecessary power usage and the risk of paging loss, this paper proposes the effective frequency/BS selection algorithm applicable to a mobile device operating in the power saving mode, which serves the device with better BS based on the tracking for channel variation. This algorithm consists of the channel estimation phase during each paging listening interval, the tracking phase for the measured results, the frequency reselection phase based on the tracking activity, and the preferred BS reselection phase. Thus the proposed method can improve the paging performance while the device is moving in the network. Also the simulation result shows that the presented scheme is superior to other candidates in energy efficiency due to the channel-adaptive frequency/BS selection.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.11-21
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• 2006

Importance of and need for grid resource management have accelerated in accordance with increasing development of grid computing. However, it is very complex to distribute and utilize resources efficiently in geographically dispersed environments. This is due to the different access policies and constraints of grid resource owners. Users request resources according to their needs. Operators of a grid computing system need to be able to monitor the system states for reflecting these demands. So, a grid computing system needs a resource management policy that monitors states of resources and then allocates resources. This paper proposes a user demand-based grid trade management model that provides an efficient resource management by the trade allocation based on a users' demand and providers' supply strategy. To evaluate performance, this paper measures increasing rate of resource trades, average response time of trades, and processing time utilization. Firstly, the average increasing rates of trade are 585.7% and 322.6% higher than an auction model and a double auction model. Secondly, the average response time of the user demand-based grid trade management model is maintained between 3 and 5 simulation time. Finally, it is found that the processing time utilization is an average of 145.4% and 118.0% higher than an auction model and a double auction model. These empirical results demonstrate the usefulness of the user demand-based grid trade management model.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.119.1-119.1
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• 2016

크라이오 워터펌프(CWP)는 크라이오 펌프(CP)와 달리 10 K 활성탄 어레이는 장착하지 않고 100 K 정도로 냉각시킨 배플만을 사용하여 물의 배기속도를 최적화 하는 데 초점을 맞춘 진공펌프다. 용기 압력이 10-9 mbar 대가 될 때까지는 잔류기체의 90% 이상이 수분이므로 다른 기체들의 배기 보다는 물을 잘 배기하는 것이 배기시간을 단축하고 도달 진공도를 낮추는 첩경이라는 아이디어에 근거를 두고 있다. CWP는 물 흡착확률을 거의 1에 가깝게 만들어서 오리피스 컨덕턴스에 육박하는 이상적인 펌프를 제작할 수 있지만 용도상 직부형(close type), 통과형(in-line type) 및 내장형(in-vessel type) 등 세 가지 다른 형태에 따라 성능도 약간씩 다르다. CWP는 모든 기체에 반응하는 정통적인 CP에 비해 훨씬 간단하고 저렴하게 만들 수 있으면서도 진공 시스템에 큰 영향을 미칠 수 있지만 물 이외의 기체들을 배기할 펌프가 필요하다는 측면에서 활용에 제약이 있다. 만일 TMP를 이미 사용하고 있거나 작은 TMP를 추가로 달아서 충분히 작동이 가능한 시스템이면서 수분 발생이 많은 곳이나, 또 활성탄의 오염이나 산소 분위기 등 CP 투입이 꺼려지는 환경이라면 CWP 사용이 좋은 선택이 될 수 있다. CWP의 물 배기용량은 CP의 알곤이나 질소 배기용량에 준하는 크기로 0.5g/cm2 이상임이 실험적으로 입증되었다. 따라서 일반적인 상황에서 정상 작동시 대부분의 기체는 TMP로 배출하고 잔류 수분만 포집하므로 CP처럼 주기적인 재생이 필요 없다. 필요하다면 CWP는 금속 표면에 응축된 물을 드라이펌프 작동만으로 쉽게 제거할 수 있고 혹시 오염 물질이 붙어도 세척이 용이하다. 이런 사용상 융통성과 여러 가지 장점에도 불구하고 그동안 물배기에 대한 인식이 미흡하고, 또 부수적이고 추가적인 비용이 드는 것으로 생각되어 주목을 받지 못했지만 디스플레이와 반도체 산업을 필두로 물 분압을 낮추고 생산수율을 높이는 것에 점점 더 관심이 높아지면서 CWP에 대한 수요도 높아지고 있다. 본 보고에서는 20인치 통과형 CWP를 만들고 14인치 TMP에 얹어 복합 진공배기시스템을 구성한 후 물 배기속도와 알곤, 질소 및 수소 배기속도를 측정하고 예측치와 비교했다. 아울러 물 배기용량 측정 및 CWP의 온도제어와 펌프재생 특성 평가 결과도 정리했다.