• Smart Media Journal
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• v.10 no.3
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• pp.31-38
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• 2021

It is hard to predict when and where a fall accident will happen. Also, if rapid follow-up measures on it are not performed, a fall accident leads to a threat of life, so studies that can automatically detect a fall accident have become necessary. Among automatic fall-accident detection techniques, a fall detection scheme using an IMU (inertial measurement unit) sensor attached to a wrist is difficult to detect a fall accident due to its movement, but it is recognized as a technique that is easy to wear and has excellent accessibility. To overcome the difficulty in obtaining fall data, this study proposes an algorithm that efficiently learns less data through machine learning such as KNN (k-nearest neighbors) and SVM (support vector machine). In addition, to improve the performance of these mathematical classifiers, this study utilized feature data aquired in the frequency space. The proposed algorithm analyzed the effect by diversifying the parameters of the model and the parameters of the frequency feature extractor through experiments using standard datasets. The proposed algorithm could adequately cope with a realistic problem that fall data are difficult to obtain. Because it is lighter than other classifiers, this algorithm was also easy to implement in small embedded systems where SIMD (single instruction multiple data) processing devices were difficult to mount.

• Journal of Cadastre & Land InformatiX
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• v.51 no.1
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• pp.39-51
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• 2021

Recently, there has been much interest in practical use of standardized HD map that can effectively define roads, lanes, junctions, road signs, and road facilities in autonomous driving. Various kinds of de jure or de facto standards such as ISO 22726-1, ISO 14296, HERE HD Live map, NDS open lane model, OpenDRIVE, and NGII HD map are currently being used. However, there are lots of differences in data modeling among these standards, it makes difficult to use them together in autonomous driving. Therefore, we propose a data model conversion method to enable an efficient use of various kinds of HD map standards in autonomous driving in this study. Specifically, we propose a conversion method between the NGII HD map model, which is easily accessible in the country, and the OpenDRIVE model, which is commonly used in the autonomous driving industry. The proposed method consists of simple conversion of NGII HD map layers into OpenDRIVE objects, new OpenDRIVE objects creation corresponding to NGII HD map layers, and linear transformation of NGII HD map layers for OpenDRIVE objects creation. Finally, we converted some test data of NGII HD map into OpenDRIVE objects, and checked the conversion results through Carla simulator. We expect that the proposed method will greatly contribute to improving the use of NGII HD map in autonomous driving.

• Journal of Convergence for Information Technology
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• v.11 no.1
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• pp.136-142
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• 2021

Open-pit mine development requires continuous management because of topographical changes and there is a risk of accidents if the current status survey is performed directly in the process of calculating the earthwork. In this study, the application of UAV photogrammetry, which can acquire spatial information without direct human access, was applied to open-pit mines development area and analyzed the accuracy, earthwork, and mountain restoration plan to determine its applicability. As a result of accuracy analysis at checkpoint using ortho image and Digital Surface Model(DSM) by UAV photogrammetry, Root Mean Square Error(RMSE) is 0.120 m in horizontal and 0.150 m in vertical coordinates. This satisfied the tolerance range of 1:1,000 digital map. As a result of the comparison of the earthwork, UAV photogrammetry yielded 11.7% more earthwork than the conventional survey method. It is because UAV photogrammetry shows more detailed topography. And result of monitoring mountain restoration showed possible to determine existence of rockfall prevention nets and vegetation. If the terrain changes are monitored by acquiring images periodically, the utility of UAV photogrammetry will be further useful to open-pit mine development.

• Journal of Digital Convergence
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• v.18 no.12
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• pp.133-138
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• 2020

The purpose of this study is to explore the methods to activate and functional changes of rural centers to improve residents' quality of life and secure sustainability in rural areas. The existing policy for activating rural centers lacks for placeness because walking-focused features of a Myeon seat have been changed due to the improvement of physical environment for easy car accessibility. They also wanted to solve abandoned houses and secure parking lots in the landscape plan. Based on analysis results, design guidelines were suggested. Long-stay tourism programs for outside visitors should be developed through the rural center activation project. They should be linked with projects for preserving the history of Byeongyeong Fortress and developing Hamel Village. Mountain trails and waterfront should be created to enhance accessibility and linkage methods with other resources should be prepared. As Byeongyeong-myeon has various tourism resources, design guidelines for each element should be made for a macroscopic direction and systematic landscape management.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.39 no.9
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• pp.41-51
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• 2010

건물의 배수 및 통기시스템에서 나타나는 현상중에 확실한 내용이 아직 밝혀지지 않은 부분이 몇 가지 남아 있다. 이것은 19세기 말엽의 근대 위생공학의 시작 단계에서부터 잘 알려진 사실이다. 건물의 배수 및 통기시스템 운용에 대한 내용은 일반 공학과 특정 유체역학의 범위 내에서 가장 잘 이해할 수 있다. 건물의 배수 및 통기시스템의 운영에 종사했던 초기의 기술진들은 이러한 점을 잘 알고 있었으며 유체역학에 적합하게 응용한 많은 사례를 확인할 수 있었다. 제2차 세계대전이 끝나고 이에 대한 많은 연구가 진행되어 왔으며 특히 유럽에서 시작된 전후 재건 붐을 통해 배수 및 통기시스템의 설계에 좀 더 효율적인 접근이 진척되게 되었다. 이러한 배수시스템의 중심에는 배수관 내부의 오염된 공기가 배수구 또는 위생기구를 통하여 주거 공간으로 유입되는 것을 방지하는 트랩(Water Trap)이 있다. 배수트랩의 주요 기능인 봉수는 일반적으로 깊이가 40 mm에서 50 mm 정도로 위생기구의 종류에 따라 봉수의 깊이는 다소 차이가 있다. 배수관내 공기의 흐름이 중요한 것처럼 트랩의 봉수 메커니즘이 중요하기 때문에 이 메커니즘을 소홀히 여긴다면 안전한 배수시스템의 운영을 기대하기는 어렵다. 배수관 내의 공기의 흐름은 배수에 의해 유입되거나 또는 배출된다. 배수관에서 내부 압력의 불규칙한 변화로 인하여 야기되는 불안정한 배수의 흐름은 트랩의 봉수를 파괴하고 나아가 주거공간으로 오염된 공기가 새어 나갈 수 있는 통로를 제공하게 된다. 관내압력의 천이는 이로 인한 문제가 발생할 가능성이 있는 위치에 그 압력을 완화할 수 있는 장치를 설계단계에 반영하여 적용함으로써 제어할 수 있다. 건물 내부에 상당한 길이의 통기배관을 설치하는 것은 배관의 마찰손실로 인하여 천이 현상을 효과적으로 제어할 수 있는 확실한 방법이 되지는 못한다. 그렇지만 통기밸브를 설치하는 것과 같이 배수관 내로 공기를 공급해주는 유입구를 건물 내부에 분산 설치하는 것이 효율적인 통기방식이 될 수 있고, 정압 천이로 인한 위험을 줄여줄 수 있다. 통기밸브는 정압 발생의 원인이 되지 않으며 단지 정압에 반응하여 더욱 기밀하게 닫히며, 약화된 압력파를 반사할 뿐이다. 고층 건물에서 배수입상관과 평행하게 설치된 통기입상관(Parallel Vent Pipe)의 경우 극히 일부분의 정압 천이 현상을 완화할 수 있다. (통기 배관의 직경이 배수 입상배관과 동일한 경우 대략 1/3 정도임), 그러므로 정압의 천이로 인한 압력 파동은 배수 시스템의 나머지 부분을 통해 전파되어 배수 트랩에 영향을 미치게 된다. 정압의 천이가 예상되는 위치에 정압천이 완화 장치(Positive Air Pressure Transient Alleviation Device)를 사용하면 배관 내부압력의 급격한 상승을 방지하여 연결된 트랩의 봉수를 보호할 수 있다. 이렇게 되면 순간적으로 발생하는 배관내 압력의 급등 현상을 90% 정도까지 완화 시킬 수 있다. 경험적으로 배수시스템에서 배관이 완전하게 막혀 과도한 정압이 발생하는 경우는 거의 없다. 이러한 경우에는 가장 낮은 위치에 있는 배수 트랩의 봉수가 깨지면서 자연스럽게 배수시스템의 압력이 해소되게 된다. 이러한 사례는 통기 방식과 상관없이 발생할 수 있다. 실제와 유사한 시뮬레이션을 통하여 통기 밸브(Air Admittance Valves)는 전면 통기 시스템 (Fully Vented System)에서 최소한 트랩의 봉수 보호용으로 적합한 것이 확인 되었다. 어떤 경우 에는 고층 건물에 더욱 적합하다는 것을 확인할 수 있었다. 부압 해소용으로 통기밸브를 이용하고 정압완화용으로 정압 완화장치(PAPAs: Positive Air Pressure Transient Attenuators)를 사용하는 전면적 능동 제어시스템(Fully Engineered Designed Active Control System)이 사용자에게 육안으로는 확인하지 못하는 기능을 보장하면서 배수 시스템의 안전과 효율성에 대한 효과적인 방법을 제공하고 있다.

• Journal of the Korean Regional Science Association
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• v.33 no.3
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• pp.31-47
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• 2017

The purpose of this study is to identify determinants of economic aid regarding housing and cost of living for the newly-married households. This study applied the binary logit model to figure out the determinants of economic aid from their parents for the households. With utilizing the Newly-Married Housing Survey data in 2015, this study found that housing characteristics and level of housing expenditure leads to the economic aid from their parents. In particular, the housing price and transportation condition increase probability the financial aid from parents when the newly-married household starts their housing career. In addition, this study found that the items of housing expenditure increase the probability of economic aid for their cost of living. To improve the independence of newly-married household, the government should adopt the housing policy for stable housing price and alleviate the burden of housing expenditure. The significance of this study is analyzing the economic aid from their parents on newly-married household regarding housing economic issues and suggest the policy for independence of living from their parents.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.1087-1094
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• 2009

As online community was revitalized, the internet became the second space for people's everyday life. People enter into a connection with other on-line members and they maintain and extend their relationships. Such relationships can be analyzed and visualized with social network analysis. The method oftentimes envisions the structural elements of complex social life. The study aims at visualizing the relationships among the Cyworld users and designs an application "Blow Blow Your Pinwheel", the main purpose of this application is visualizing social relationships between ego and '1chons' which is a concept of friendship in Cyworld. Designing such an application, the study focuses on closeness of relationships which we think is composed of 1)proximity 2)similarity, 3)familiarity, and 4)reciprocity. The study used these concepts in measuring the strength of relationship between ego and other 1chons(friends). Specifically, we devised survey questionnaires which asked users to evaluate the importance of the above factors of closeness, and implemented the result in calculating the strength of the relationship between ego and other by giving weights for each factor. These measurements then were applied in visualizing the relationships in the application, we designed. Through the application, we can compare on-line relationships with off-line relationships and attempt for the new approach of Social Networks.

• The Journal of the Korea Contents Association
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• v.18 no.2
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• pp.553-568
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• 2018

Popular music is a spce where intrinsic desires and values of young people are well exposed in its process of production and consumption. Previous discussions of Korean youth and youth culture have been proceeding mainly in the sense of their resistances to older generation. However, this is limited in that it neglects the inherent microscopic characteristics of youth culture. The purpose of this study is to investigate what the signs and discourses of youth generation make and share in popular music, and how it relates to social context through the 'Mimesis' theory. As a result, the songs of the 1990s remarkably showed the resistance to the old generation in its narrative structure and have signs which expresses repression and uniformity. On the other hand, the songs of the 2010s have many fragmented signs which has been reconstructed into individualized discourse structure. It is assumed that the songs have been able to gain a lot of empathy and popularity from the young generation by visualizing emotions and desires experienced by themselves in the social context. Through this study, it suggests to pay attention to the sensitivity, desire and creativity of young people in music in the social and cultural context of the time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8C
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• pp.633-641
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• 2008

Since WSNs encounter attacks, such as jamming or eavesdropping without physical access occurs, security is one of the important requirements for WSNs. The key pre-distribution scheme that was recently researched for advance of security in WSNs distributes the keys and probability with the use of q-composite random key pre-distribution method, but there is a high probability that no key shared between sensor nodes, and it takes a lot of time and energy to find out the shared key. Therefore, it is not suitable for WSNs. In order to enhance stability of a node that plays a role of gateway without depending on probabilistic key, this paper proposesa key pre-distribution scheme combined with random key pre-distribution scheme and double hash chain. Since the proposed scheme can maintain a small storage place and strong security strengths, it is more efficient than the existing schemes with the same security strengths. In addition, since it uses a small size of key generation key set, it can reduce a great deal of storage overhead.

• Journal of the Korea Computer Graphics Society
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• v.26 no.1
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• pp.17-25
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• 2020

We present a novel multi-core CPU based parallel algorithm for the cell-connectivity information extraction algorithm, which is one of the preprocessing steps for volume rendering of unstructured grid data. We first check the synchronization issues when parallelizing the prior serial algorithm naively. Then, we propose a 3-step parallel algorithm that achieves high parallelization efficiency by removing synchronization in each step. Also, our 3-step algorithm improves the cache utilization efficiency by increasing the spatial locality for the duplicated triangle test process, which is the core operation of building cell-connectivity information. We further improve the efficiency of our parallel algorithm by employing a memory pool for each thread. To check the benefit of our approach, we implemented our method on a system consisting of two octa-core CPUs and measured the performance. As a result, our method shows continuous performance improvement as we add threads. Also, it achieves up to 82.9 times higher performance compared with the prior serial algorithm when we use thirty-two threads (sixteen physical cores). These results demonstrate the high parallelization efficiency and high cache utilization efficiency of our method. Also, it validates the suitability of our algorithm for large-scale unstructured data.