오토인코더 기반의 그룹 추천을 위한 사용자 클러스터링

임재형(Jaehyung Lim),박진태(Jintae Park),박대영(Daeyoung Park) 한국통신학회 2023 한국통신학회 학술대회논문집 Vol.2023 No.2

저차원 클러스터링을 통한 그룹 추천시스템

임재형(JaeHyung Lim),이승주(SeungJoo Lee),서영덕(Young-Duk Seo) 한국정보기술학회 2022 Proceedings of KIIT Conference Vol.2022 No.6

다양한 플랫폼 환경의 사용자가 늘어나면서 개인 추천시스템 이외에도 비슷한 소비 형태를 지닌 사용자들을 대상으로 하는 그룹 추천시스템의 필요성이 커지고 있다. 그룹을 만들기 위해 우선 사용자들의 특성을 분석해야 하므로, 본 논문에서는 행렬 분해 모델을 통해 사용자들을 나타낼 수 있는 저차원의 특성 벡터를 클러스터링 하였다. 이를 기반으로 성능 평가를 실시해 본 결과 그룹이 추천해준 아이템에 대하여 사용자들도 실제로 선호도가 높다는 것을 확인하였다. As the number of users of various platform environments increases, there is a growing need for a group recommender system targeting users with similar consumption patterns. We first analyze the characteristics of users to create a group. Then, we cluster low-dimensional characteristic vectors that can represent users through a matrix factorization models. As a result of comparative evaluations based on this, we verify that users actually have high preference for the items recommended by the group.

KINGS: A Preliminary Result of the Fornax cluster

JaeHyung Lee,Myung Gyoon Lee,Sungsoon lim,Jubee Sohn,In Sung Jang,Jinhyuk Ryu,wang-Ho Lee,Youkyung Ko,Jung Hwan Lee 한국천문학회 2016 天文學會報 Vol.41 No.1

Microstructure Evolution and Mechanical Properties of Al/Al-Mg/Al composite sheet metals

Jaehyung Cho,Su-Hyeon Kim,Hyoung-Wook Kim,Cha-Yong Lim,Eun-Young Kim,Shi-Hoon Choi 한국소성가공학회 2011 기타자료 Vol.2011 No.8

Two different types of aluminum alloys of AA1050 and AA5182 were used to manufacture Al/Al-Mg/Al composite sheet metals by roll bonding technology at room temperature. The composite sheet metals were annealed at 400℃ and carried out uniaxial tension tests to investigate mechanical properties. Macroscopic mechanical properties are strongly dependent on the volume (or thickness) fraction of two component layers. Microstructure and texture evolution were also investigated during roll bonding process. The AA1050 sheets located in the outer layer mainly consist of shear texture components and the AA5182 sheet located in the center layer consists of plane strain texture components. With differential speeds of the top and bottom rolls, roll bonding was also carried out. Elongation along the RD and TD was improved at a speed difference of approximately 10%?20%.

KMTNet Test Observation of Nearby Southern Galaxy Groups

JaeHyung Lee,Sungsoon Lim,Jubee Sohn,In Sung Jang,Jinhyuk Ryu,Youkyung Ko,Myung Gyoon Lee 한국천문학회 2015 天文學會報 Vol.40 No.1

Compact Optical Autocorrelator with 0.1-Meter Scanning Range Using a Rotating Pair of Mirrors

장재형(Jaehyung Jang),이승후(Seunghoo Lee),이우정(Woojeong Lee),임현우(Hyeonwoo Lim),이주형(Joohyung Lee) Korean Society for Precision Engineering 2021 한국정밀공학회지 Vol.38 No.5

A study on calculation of friction coefficient and packing stress using static diagnosis test for a balanced globe valve in nuclear power plants

Kim, Jaehyung,Lim, Taemook,Ryu, Ho-Geun Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.8

A valve assembly used in nuclear power plants must be qualified and supervised. New technical standards such as ASME QME-1 2007 particularly require detailed qualification using experiment and analysis. Particularly, diagnostic tests and engineering studies are required for qualification of ASME QME-1 2007. Among these studies, the research on the measurement of friction coefficient and packing stress is important. The irregular change of packing stress along the stroke distance occurs because of the abnormal phenomenon, which must be found and studied with quantitative methods. Packing stress should be analyzed conservatively through experimentation and analysis. In this study, various formulas were applied to measure and calculate coefficient of friction and packing stress. This study can be used in relation to qualification and supervision of packing materials. And the calculation using static diagnosis test can be used to find the packing frictional force in dynamic diagnosis test with flow pressure in a pipe. This study has made it possible to reliably consider packing frictional force generated in a valve body. And so, it is believed that more margin can be secured when evaluating the capacity of valve actuator by applying the accurate frictional force generated in the valve assembly.

Long-term Effects of the Eradication of Helicobacter pylori on Metabolic Parameters, Depending on Sex, in South Korea

Park Jaehyung,Kim Nayoung,Kim Won Seok,Lim Seon Hee,Choi Yonghoon,Jo Hyeong Ho,Ji Eunjeong,Yoon Hyuk,Shin Cheol Min,Park Young Soo,Lee Dong Ho 거트앤리버 소화기연관학회협의회 2023 Gut and Liver Vol.17 No.1

Background/Aims: Helicobacter pylori (HP) infection is positively associated with metabolic syndrome (MS). However, the long-term effects of eradication therapy on MS and sex differences have not been thoroughly studied. We aimed to investigate the long-term effects of HP eradication on MS and sex differences. Methods: This study included 2,267 subjects who visited a tertiary referral center between May 2003 and May 2019. HP was diagnosed by histology, a Campylobacter-like organism test, and culture, and the subjects were prospectively followed up. The participants were categorized into three groups: HP uninfected, HP infected but non-eradicated, and HP eradicated. The baseline characteristics and changes in metabolic parameters after HP eradication were compared over a 5-year follow-up period. Results: Among 1,521 subjects, there was no difference in baseline metabolic parameters between the HP-uninfected (n=509) and HP-infected (n=1,012) groups, regardless of sex. Analysis of the metabolic parameters during follow-up among HP-uninfected (n=509), HP-non-eradicated (n=346), and HP-eradicated (n=666) groups showed that high-density lipoprotein (HDL) and the body mass index (BMI) increased after eradication, with a significant difference at 1-year of follow-up. In females, HDL increased after eradication (p=0.023), and the BMI increased after eradication in male subjects (p=0.010). After propensity score matching, the HDL change in female remained significant, but the statistical significance of the change in BMI in the male group became marginally significant (p=0.089). Conclusions: HP eradication affected metabolic parameters differently depending on sex. HDL significantly increased only in females over time, especially at 1-year of follow-up. In contrast, BMI showed an increasing tendency over time in males, especially at the 1-year follow-up.

조세지출의 범위에 관한 연구

장재형(Jaehyung Jang),임재현(Jaehyeon Lim) 한국국제조세협회 2015 조세학술논집 Vol.31 No.2

The credibility of tax law as a subpart of the legal system depends on the preciseness of its concepts and scopes thereof. Tax expenditures, as one of the groundwork for tax law, need detailed analysis and review. Many important financial control systems such as the tax expenditure budgetary system required by the 「National Finance Law」 amended in 2010 or the preliminary feasibility study on new tax preferential regulation required by the 「Tax Reduction and Exemption Control Act」 amended in 2014 are based on the concept and the scope of tax expenditures. Since the tax expenditures are the exception to the benchmark tax system, constitutional principles should be applied in a different way. In view of tax equalitarianism, tax expenditures should be kept at a minimum necessary level, and the benefit of the doubt in the interpretation of the clause (in dubio pro fisco) should be given to the tax authority. Tax expenditures defined in the 「Tax Reduction and Exemption Control Act」 and the 「Tax Expenditure Budgetary Report」 are “departure from the benchmark tax system, such as tax exemption, tax reduction, tax credit, tax allowance, preferential tax rate or tax deferral made under certain requirements, having the characteristic of financial expenditures.” Tax expenditures of Republic of Korea in 2015 amounted to 33.5 trillion won, among which 18.5 trillion won are from the 「Tax Reduction and Exemption Control Act」 and 14.5 trillion won are from individual tax law such as the 「Income Tax Law」. Main objective of this study is to ascertain whether the items of the Tax Expenditure Budgetary Report match the definition of tax expenditures. Different countries have used various specific criteria for the tax expenditures. The United States and Canada use a broadly defined definition for tax expenditures, while the United Kingdom and Germany apply a narrower scope of tax expenditures. The United Kingdom distinguishes between tax expenditures and ‘structural reliefs’, and Germany only makes reference to aid to enterprises and business sectors of the economy. In particular, many countries commonly exclude some measures from the scope of tax expenditures, such as a allowance for family units, credit for pension, and a tax deferral, because these measures lack particularity concerning beneficiaries, do not serve a particular purpose other than the efficient operation of the tax system, and are not administratively feasible to eliminate. If the tax expenditures included in the 「Tax Expenditure Budgetary Report」 are analyzed by the same logic, some measures have more characteristics of the structural norm than of tax expenditures. Even under the broadest definition for tax expenditures, personal or family allowances for individual income tax, deemed input VAT credit, and pension credit, which constitute over 20 percent of the entire amount of tax expenditures, are more of the structural norm than tax expenditures. Although the number of such measures is not so high, since their revenue amounts are large in sum, they can distort the tax policy. Accordingly, the scope and concept of tax expenditures must be defined in a lucid manner and in concordance with internationally used criteria for tax expenditures. Then, the tax policy on the reduction of tax expenditures will be clearly made and be implemented without.

원전용 게이트 밸브의 성능특성 분석을 위한 유동해석 모델링 연구

김재형(Jaehyung Kim),임태묵(Taemook Lim),이정희(Jung Hee Lee) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.4

The 3D flow analysis model on gate valve in nuclear power plant is made and validated by known experimental equation, which is the requirement of ASME QME-1 standard. The major loss on valve is calculated and compared to Swamee-Jain equation, where the error of pipe friction coefficient is within 7% error bound. The minor loss on valve is calculated but cannot be compared because of no experimental equation. So the orifice is inserted on pipe instead of valve and the differential pressure and flow rate is used to calculate the discharge coefficient (Cd value) with various size of flow passage. With the validated mesh and model, the flow analysis of gate valve was performed with changing stoke and reynolds number. The minor loss in valve is dominant when the valve is operated and the force on disk is larger with increasing reynolds number. Valve factor, which accounts the loss effect by differential pressure force, is calculated with the flow analysis result. The valve factor can be used in calculation of valve force in design and functional qualification.