• Annual Conference of KIPS
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• 2009.04a
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• pp.364-368
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• 2009

"소셜 네트워크(Social Network)와 검색(Search)의 만남"은 현재 인터넷 상에서 매우 의미 있는 두 영역의 결합이다. 이와 같은 두 영역의 결합을 통해 소셜 네트워크 내에서 친구들의 생각이나 관심사 및 활동을 검색하고 공유함으로써 검색의 효율성과 적합성을 높이기 위한 연구들이 활발히 수행되고 있다. 본 논문에서는 일반적인 소셜 관계 랭크(SRR : Social Relation Rank) 및 토픽이 반영된 소셜 관계 랭크(TS_SRR : Topic Sensitive_Social Relation Rank) 알고리즘을 제안한다. SRR은 소셜 네트워크 내에 존재하는 웹 사용자들의 내재적인 특성 및 검색 성향 등에 대한 관련성(또는 유사정도)을 수치로 산정한 '소셜 관계 지수(SRV : Social Relation Value)'에 랭킹(Ranking)을 부여한 것을 의미한다. 제안하는 알고리즘의 검색 적용 가능성을 검증하기 위해 첫째, 웹 사용자간 직접 또는 간접적인 연결로 구성된 소셜네트워크를 구성 한다. 둘째, 웹 사용자들의 속성에 내재된 정보를 이용하여 토픽별 SRV를 산정한 후 랭킹을 부여하고, 토픽별 변화되는 랭킹에 따라 소셜 네트워크를 재구성 한다. 마지막으로 (TS_)SRR과 웹 사용자들의 검색 패턴(Search Pattern)을 비교 실험 한다. 실험 결과 (TS_)SRR이 높은 웹 사용자 간에는 검색 패턴 또한 유사함을 확인 하였다. 결론적으로 (TS_)SRR 알고리즘을 기반으로 관심분야에 연관성이 높은, 즉 상위에 랭크 된 웹 사용자들을 검색하여 검색 패턴을 공유 또는 상속받는 다면 개인화 검색(Personalized Search) 및 소셜 검색(Social Search)의 효율성과 신뢰성 향상에 기여 할 수 있다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.186-186
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• 2022

강수 및 침투 등으로 발생하는 지하수위의 변동을 예측하는 것은 지하수 자원의 활용 및 관리에 필수적이다. 지하수위의 변동은 지하수 자원의 활용 및 관리뿐만이 아닌 홍수 발생과 지반의 응력상태 등에 직접적인 영향을 미치기 때문에 정확한 예측이 필요하다. 본 연구는 인공신경망 중 다층퍼셉트론(Multi Layer Perceptron, MLP)을 이용한 지하수위 예측성능 향상을 위해 MLP의 구조 중 Optimizer를 개량하였다. MLP는 입력자료와 출력자료간 최적의 상관관계(가중치 및 편향)를 찾는 Optimizer와 출력되는 값을 결정하는 활성화 함수의 연산을 반복하여 학습한다. 특히 Optimizer는 신경망의 출력값과 관측값의 오차가 최소가 되는 상관관계를 찾는 연산자로써 MLP의 학습 및 예측성능에 직접적인 영향을 미친다. 기존의 Optimizer는 경사하강법(Gradient Descent, GD)을 기반으로 하는 Optimizer를 사용했다. 하지만 기존의 Optimizer는 미분을 이용하여 상관관계를 찾기 때문에 지역탐색 위주로 진행되며 기존에 생성된 상관관계를 저장하는 구조가 없어 지역 최적해로 수렴할 가능성이 있다는 단점이 있다. 본 연구에서는 기존 Optimizer의 단점을 개선하기 위해 지역탐색과 전역탐색을 동시에 고려할 수 있으며 기존의 해를 저장하는 구조가 있는 메타휴리스틱 최적화 알고리즘을 이용하였다. 메타휴리스틱 최적화 알고리즘 중 구조가 간단한 화음탐색법(Harmony Search, HS)과 GD의 결합모형(HS-GD)을 MLP의 Optimizer로 사용하여 기존 Optimizer의 단점을 개선하였다. HS-GD를 이용한 MLP의 성능검토를 위해 이천시 지하수위 예측을 실시하였으며 예측 결과를 기존의 Optimizer를 이용한 MLP 및 HS를 이용한 MLP의 예측결과와 비교하였다.

• Journal of Aerospace System Engineering
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• v.18 no.2
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• pp.47-55
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• 2024

The paper presents a docking-type automatic landing system that works in tandem with Unmanned Aerial Vehicles (UAVs) and Unmanned Surface Vehicles (USVs). The system utilizes a pyramid-shaped landing gear and pad for effective landing. In marine environments, a docking device guides the drone to land securely. To test the system, a ship's behavior was simulated using a 3-DoF motion platform, and the successful operation and utility of the docking-type automatic landing system were demonstrated.

• The Journal of Engineering Geology
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• v.34 no.2
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• pp.295-315
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• 2024

Urban development and the expansion of electrical resistivity surveying applications have increased the need for soil and underground structure investigations on paved surfaces. Traditional methods involved drilling through the pavement or surveying surrounding soil. Recently, non-invasive surveying techniques have been developed. This paper analyzes these methods, categorizing them into galvanic methods (including drilling and flat ground electrodes) and capacitive coupling methods. By examining case studies, it suggests selecting the appropriate method based on the pros and cons of each and the specific site characteristics. The paper also discusses the applicability and limitations of electrical resistivity surveying through various examples.

• Economic and Environmental Geology
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• v.36 no.3
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• pp.243-255
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• 2003

The mathematical models for GIS-based spatial data integration have been developed for geological applications such as mineral potential mapping or landslide susceptibility analysis. Among various models, the effectiveness of fuzzy logic based integration of multiple sets of geological data is investigated and discussed. Unlike a traditional target-driven fuzzy integration approach, we propose a data-driven approach that is derived from statistical relationships between the integration target and related spatial geological data. The proposed approach consists of four analytical steps; data representation, fuzzy combination, defuzzification and validation. For data representation, the fuzzy membership functions based on the likelihood ratio functions are proposed. To integrate them, the fuzzy inference network is designed that can combine a variety of different fuzzy operators. Defuzzification is carried out to effectively visualize the relative possibility levels from the integrated results. Finally, a validation approach based on the spatial partitioning of integration targets is proposed to quantitatively compare various fuzzy integration maps and obtain a meaningful interpretation with respect to future events. The effectiveness and some suggestions of the schemes proposed here are illustrated by describing a case study for landslide susceptibility analysis. The case study demonstrates that the proposed schemes can effectively identify areas that are susceptible to landslides and ${\gamma}$ operator shows the better prediction power than the results using max and min operators from the validation procedure.

• Management & Information Systems Review
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• v.32 no.1
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• pp.195-216
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• 2013

This Study investigates evaluation policies for goodwill under the current tax law and suggests improvements as follows. First, even though not appear on the financial statements of acquiree at the date of acquisition, the current corporate tax raw regulates that firms need to estimate purchased goodwill including acquisition amount and additionally recognizable intangible property right with no distinction. According to this rule, purchased goodwill from business combination under the current tax raw has a drawback in overestimating. So, there is need of further improvement on the current related purchased goodwill regime to distinguish additionally recognized intangible property right from purchased goodwill. Second, in the consideration of internally generated goodwill, suggested in the current inheritance and gift tax act as a supplementary evaluation technique, the estimated value of goodwill may contain some bias, since the current regulation uniformly applies to all the companies with no industry characteristics. This may particularly become problematic while computing abnormal earnings, uniformly applying the 10% normal return to all the companies since the normal return is not likely to reflect industry characteristics and thus the computed abnormal earnings may be biased. Therefore, there is need to revise the current regulation relating to the normal return, to convert from the existing 10% rule to the industry average rate of return method.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.5
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• pp.438-447
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• 2004

A new multilevel PWM inverter using a half-bridge and full-bridge cells is proposed for the use of stand-alone photovoltaic inverters. The configuration of the proposed multilevel PWM inverter is based on a prior 11-level shaped PWM inverter. Among three full-bridge cells employed in the prior inverter, one cell is substituted by a half-bridge cell. Owing to this simple alteration, the proposed inverter has three promising merits. First it increases the number of output voltage levels resulted in high quality output voltages. Second, it reduces two power switching devices by means of employing a half-bridge cell. Third, it reduces power imposed on a transformer connected with the half-bridge unit. That is to say, most power is transferred to loads via cascaded transformers connected with low switching inverters, which are used to synthesize the fundamental output voltage levels whereas the output of a transformer linked to a high switching inverter is used to improve the final output voltage waves; thus, it is desirable in the point of the improvement of the system efficiency. By comparing to the prior 11-level PWM inverter, it assesses the performance of the proposed inverter as a stand-alone photovoltaic inverter. The validity of the proposed inverter is verified by computer-aided simulations and experimental results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.492-497
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• 2019

This study analysed the legal concept of personal information(PI), which was not differentiated from behavioral information, and established it clearly for invigorating online targeted advertising(OTA), which draw attention in big data era; by selecting Guidelines of Assessment of Data Breach Incident Factors and Guidelines of Measures for No-Identifying Personal Information based on Personal Information Protection Act(PIPA) and Enforcement Decree of the PIPA. As a result, PI was defined as any kind of information relating to (1)a living individual(not group, corporate body or things etc.); (2)makes possibly identify the individual by his or her identifiers such as name, resident registration number, image, etc. (not included if not identify the individual); and (3)including information like attribute values which makes possibly identify any specific individual, if not by itself, but combined with other information which can be actually collected and combined). Specifically, PI includes basic, proper distinguishable, sensitive and other PI. It is suggested that PI concept should be researched continually with digital technology development; the effectiveness of the Guidelines of PI Protection in OTA, the legal principles of PI protection from not only users' but business operators' perspectives and the differentiation between PI and behavioral information in OTA should be researched.

• Korean Journal of Poultry Science
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• v.46 no.3
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• pp.173-183
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• 2019

Based on their virulence, the avian influenza viruses (AIVs) are classified into two pathotypes: low pathogenic avian influenza (LPAI) virus and highly pathogenic avian influenza (HPAI) virus. Among the 16 HA subtypes of AIV, only the H5 and H7 subtypes are classified as HPAI. Some AIVs, including H5 and H7 viruses, can infect humans directly. Six H7 subtype isolates from wild birds of the H7N7 (n=4) and H7N1 (n=2) subtypes were characterized in this study. Phylogenetic analysis showed that eight viral genes (HA, NA, PB2, PB1, PA, NP, M, and NS) of the H7 isolates clustered in the Eurasian lineage, the genetic diversity of which is indicated by its division into several sublineages. The Korean H7 isolates had two motifs, PEIPKGR and PELPKGR, at the HA cleavage site, which have been associated with LPAI viruses. Six H7 isolates encoded glutamine (Q) and glycine (G) at positions 226 (H3 numbering) and 228 of HA, suggesting avian-type receptor-binding specificity. None of the Korean H7 isolates had the amino acid substitutions E627K in PB2 and I368V in PB1, which are critical for efficient replication in human cells. The Korean H7 isolates showed no deletions in the NA stalk region and in NS. These results suggest that the Korean H7 isolates from wild birds are different from the H7N9 influenza viruses isolated in China in 2013, which are capable of infecting humans.

• The Korean Journal of Nuclear Medicine
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• v.37 no.4
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• pp.235-244
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• 2003

Purpose: Attention deficit hyperactivity disorder (ADHD) has been known as psychiatric disorder in childhood associated with dopamine dysregulation. In present study, we investigated changes in dopamine transporter (DAT) density of the basal ganglias using I-123 N-(3-iodopropen-2-yl) -2-carbomethoxy-3beta-(4-chlorophenyl) tropane [I-123 IPT] SPECT in children with ADHD before and after methylphenidate treatment. Materials and Method: Nine drug-naive children with ADHD and seven normal children were included in the study. We peformed brain SPECT two hours after the intravenous administration of I-123 IPT and made both quantitative and qualitative analyses using the obtained SPECT data, which were reconstructed for the assessment of soecific/nonspecific DAT binding ratios in the basal ganglia. All children with ADHD reperformed [123I]IPT SPECT after treatment with methylphenidate(0.7mg/kg/d) during about 8 weeks. SPECT data reconstructed for the assessment of specific/nonspecific DAT binding ratio of the basal ganglia were compared between before and after treatment methylphenidate. We investigated correlation between the change of ADHD symptom severity assessed with ADHD rating scale-IV and specific/nonspecific DAT binding ratio of basal ganglia. Results: Children with ADHD had a significantly greater specificinonspecific DAT binding ratio of the basal ganglia comparing to normal children(Right : z = 2.057, p = 0.041 : Left : z : 2.096, p = 0.032). Under treatment with methylphenidate in all children with ADHD, specificinonspecific DAT binding ratio of both basal ganglia decreased significantly greater than before treatment with methylphenidate (Right : t = 3.239, p = 0.018 ; Left : t = 3.133, p = 0.020). However, no significant correlation between the change of ADHD symptom severity scores and specific/nonspecific DAT binding ratio of the basal ganglia were found. Conclusions: These findings support the complex dysregulation of the dopaminergic neurotransmitter system in children with ADHD.