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Supersonic Cavity Based Combustion with Kerosene/Hydrogen Fuel

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Journal of Thermal Science 2015年第2期24卷 164-172页

作者： Rajarshi Das Jeong soo kim Heuy Dong kim Department of Mechanical Engineering Andong National University School of Mechanical Engineering Pukyong National University

A comparative study with kerosene and hydrogen fuel in a model scramjet combustor has been carried out nu- merically. The effect of fuel-air equivalence ratio on the flow field properties in a cavity based mixing mechanism at a freestream Math number of 2.08 has been probed. The investigation has been carried out in a two dimension- al numerical model where a cavity of length to depth ratio of 2 is mounted on one of the walls of the flow channel The flow field shock structure is observed to change with the change in fuel-air equivalence ratio. Total pressure loss is observed to depend both on fuel air equivalence ratio and the fuel type. The spread of fuel in the test sec- tion shows marked variation with the equivalence ratio. Performance of injector location on the fuel-air mixing is also probed during the course of the investigation.

关键词： Scramjet fuel-air mixing kerosene hydrogen equivalence ratio

Some Theorems on Leibniz n-Algebras from the Category U_(n)(Lb)

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Algebra Colloquium 2021年第1期28卷 155-168页

作者： Min soo kim Rustam Turdibaev Vanderbilt University NashvilleTN 37235USA V.I.Romanovskiy Institute of Mathematics Uzbekistan Academy of SciencesUniversity Street 4bTashkent 100174Uzbekistan AKFA University 1st Deadlock 10Kukcha DarvozaTashkent 100095Uzbekistan

We study the Leibniz n-algebra U_(n)(L),whose multiplication is defined via the bracket of a Leibniz algebra L as[x1,…,xn]=[x1,[…,[xn−2,[xn−1,xn]]…]].We show that U_(n)(L)is simple if and only if L is a simple Lie *** analog of Levi's theorem for Leibniz algebras in U_(n)(Lb)is established and it is proven that the Leibniz n-kernel of U_(n)(L)for any semisimple Leibniz algebra L is the n-algebra U_(n)(L).

关键词： Leibniz n-algebra Leibniz n-kernel simple Leibniz n-algebra Levi decomposition

A New FIR Filter for State Estimation and Its Application

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Journal of Computer Science & Technology 2007年第5期22卷 779-784页

作者： Pyung-soo kim Myung-Eui Lee Department of Electronics Engineering Korea Polytechnic University Shiheung CityKgunggi-DoKorea School of Information Technology Korea University of Technology and Education Cheonan City Chungnam-DoKorea

This paper proposes a new FIR （finite impulse response） filter under a least squares criterion using a forgetting factor. The proposed FIR filter does not require information of the noise covariances as well as the initial state, and has some inherent properties such as time-invariance, unbiasedness and deadbeat. The proposed FIR filter is represented in a batch form and then a recursive form as an alternative form. Prom discussions about the choice of a forgetting factor and a window length, it is shown that they can be considered as useful parameters to make the estimation performance of the proposed FIR filter as good as possible. It is shown that the proposed FIR filter can outperform the existing FIR filter with incorrect noise covariances via computer simulations. Finally, as a useful application, an image sequence stabilization problem is considered. Through this application, the FIR filtering based approach is shown to be superior to the Kalman filtering based approach.

关键词： state estimation FIR (finite impulse response) filter Kalman filter least squares forgetting factor

Ultimate strength of single shear bolted connections with cold-formed ferritic stainless steel

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第2期14卷 120-136页

作者： Jin-seong LIM Tae-soo kim Seung-hun kim Department of Architectural Engineering Hanbat National UniversityDaejeon 305-719Korea

This paper is focused on the structural behavior of the single shear bolted connections with thin-walled ferritic stainless *** purpose of this study is to investigate the ultimate behaviors,such as ultimate strength and fracture mode of the single shear bolted connections of thin-walled ferritic stainless steel(low cost steel) rather than austenitic stainless steel(high cost steel).Bolt arrangement and end distance parallel to the direction of applied load are considered as main variables of the test specimens for bolted *** have a constant dimension of edge distance perpendicular to the loading direction,bolt diameter,pitch,and gauge.A monotonic tensile test for specimens has been carried out and some bolted connections with long end distance showed curling(out of plane deformation) occurrence which led to strength *** ultimate behaviors such as fracture mode,ultimate strength are compared with those predicted by current design ***,conditions of curling occurrence and the strength reduction due to curling are investigated and modified strength equations are suggested considering the curling effect.

关键词： Cold-formed ferritic stainless steel Bolted connection Bolt arrangement End distance Curling Strength reduction

Generation of mesenchymal stem-like cells for producing extracellular vesicles

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World Journal of Stem Cells 2019年第5期11卷 270-280页

作者： soo kim Tae Min kim Brexogen Research Center Brexogen Inc. Seoul Songpa-gu 05718 South Korea Graduate School of International Agricultural Technology and Institute of Green- Bio Science and Technology Seoul National University Gangwon-do Pyeongchang 25354 South Korea

Mesenchymal stem cells (MSCs) are multipotent progenitor cells with therapeutic potential against autoimmune diseases, inflammation, ischemia, and metabolic disorders. Contrary to the previous conceptions, recent studies have revealed that the tissue repair and immunomodulatory functions of MSCs are largely attributed to their secretome, rather than their potential to differentiate into desired cell types. The composition of MSC secretome encompasses cytokines and growth factors, in addition to the cell-derived structures known as extracellular vesicles (EVs). EVs are membrane-enclosed nanoparticles that are capable of delivering biomolecules, and it is now believed that MSC-derived EVs are the major players that induce biological changes in the target tissues. Based on these EVs’ characteristics, the potential of EVs derived from MSC (MSC-EV) in terms of tissue regeneration and immune modulation has grown during the last decade. However, the use of MSCs for producing sufficient amount of EVs has not been satisfactory due to limitations in the cell growth and large variations among the donor cell types. In this regard, pluripotent stem cells (PSCs)-derived MSC-like cells, which can be robustly induced and expanded in vitro, have emerged as more accessible cell source that can overcome current limitations of using MSCs for EV production. In this review, we have highlighted the methods of generating MSC-like cells from PSCs and their therapeutic outcome in preclinical studies. Finally, we have also discussed future requirements for making this cell-free therapy clinically feasible.

关键词： Mesenchymal stem cells Extracellular vesicles Preclinical studies Exosomes

Engaging in sports via the metaverse? An examination through analysis of metaverse research trends in sports

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Data Science and Management 2024年第3期7卷 181-188页

作者： Ahyun kim Sang-soo kim Department of Business Administration Dongyang Mirae UniversitySeoul08221South Korea Department of Business Administration Yong in UniversityGyeonggi-do17092South Korea

In sports, virtual spaces are sometimes utilized to enhance performance or user experience. In this study, we conducted a frequency analysis, semantic network analysis, and topic modeling using 134 abstracts obtained through keyword searches focusing on “sport(s)” in combination with “metaverse”, “augmented reality”, “virtual reality”, “lifelogging”, and “mixed reality”. First, the top 20 words were extracted through frequency analysis, and then each type of extracted word was retained to select seven words. The analysis revealed the emergence of key themes such as “user(s)”, “game(s)”, “technolog(y/ies)”, “experience(d)”, “physical”, “training”, and “video”, with variations in intensity depending on the type of metaverse. Second, the relationships between the words were reconfirmed using semantic networks based on the seven selected words. Finally, topic modeling analysis was conducted to uncover themes specific to each type of metaverse. We also found that “performance/scoring” was a prominent word across all types of metaverses. This suggests that in addition to providing enjoyment through sports, there is a high possibility that all users (both general users and athletes) utilize the metaverse to achieve positive outcomes and success. The importance of “performance/scoring” in sports may seem obvious;however, it also provides significant insights for practitioners when combined with metaverse-related keywords. Ultimately, this study has managerial implications for enhancing the performance of specialized users in the sports industry.

关键词： Sport Metaverse Frequency analysis Topic modeling Semantic network analysis

Factors associated with strabismus after cataract extraction and primary intraocular lens implantation in congenital cataracts

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International Journal of Ophthalmology(English edition) 2014年第3期7卷 522-527页

作者： soo Jung Lee Wan-soo kim Department of Ophthalmology Haeundae Paik Hospital

AIM:To evaluate factors associated with the development of strabismus after cataract extraction and primary intraocular lens ***:The medical records of 122 patients,aged1.5mo to 9y,who had undergone cataract extraction with primary intraocular lens implantation between January1993 and August 2011 were *** patients(17 eyes)with strabismus before cataract surgery were *** were divided into those with congenital bilateral cataracts(64 patients,128 eyes)and those with unilateral cataracts(44 patients,44 eyes).The associations between the development of strabismus and age at cataract surgery,pre-and post-cataract extraction corrected distance visual acuity(CDVA),interocular CDVA difference,nystagmus,surgical method,and secondary cataract were ***:Factors significantly associated with the development of strabismus included age at cataract surgery(≤1y),preoperative mean CDVA≤20/100,presence of nystagmus in the bilateral cataract group and postoperative interocular CDVA difference>20/70 in the unilateral *** CDVA≤20/100 and preservation of posterior capsule,and presence of secondary cataract were significant factors in both ***:Children with congenital cataracts should be monitored carefully after cataract surgery for the development of strabismus,especially when they underwent surgery at age≤1y,and they have nystagmus,large postoperative interocular CDVA difference,poor preoperative and postoperative CDVA,preservation of the posterior capsule,or secondary cataract.

关键词： strabismus congenital cataract nystagmus

Factors influencing stereoacuity levels after surgery to correct unilateral developmental cataracts in children

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International Journal of Ophthalmology(English edition) 2013年第3期6卷 331-336页

作者： soo Jung Lee Wan-soo kim Department of Ophthalmology Haeundae Paik Hospital

·AIM: To evaluate factors influencing stereoacuity after surgery to correct unilateral developmental pediatric cataracts. ·METHODS: We retrospectively surveyed 110 patients who had undergone removal of unilateral acquired developmental cataracts and primary posterior chamber intraocular lens implantation between February 1992 and December 2009. In all patients, stereoacuity was assessed using the Titmus test at the last follow -up period of minimum 2 years after surgery. Patients were divided into two groups according to the extent of stereoacuity : group 1 ( = 42 ) had stereoacuity values ≤ 100sec/arc and group 2 ( =68) values >100sec/arc. The values of ten parameters associated with stereoacuity were measured in each group: Cataract types, preoperative best corrected visual acuity (BCVA) of the affected eyes, preoperative inter -ocular difference of BCVA, age at cataract surgery, operative method, secondary cataract, postoperative strabismus, postoperative BCVA of the affected eyes, postoperative inter-ocular difference of BCVA, and anisometropia. ·RESULTS: The extent of stereoacuity was significantly associated with both operative method and secondary cataract ( =0.000 and =0.016, respectively). All patients in whom the posterior capsule was preserved, had poor stereoacuity >100sec/arc. Significant correlations with the extent of stereoacuity were found with postoperative strabismus ( =0.048),postoperative BCVA of the affected eyes ( =0.002), anisometropia ( =0.034). ·CONCLUSION: Postoperative stereoacuity was better in patients who underwent either optic capture or anterior vitrectomy after posterior continuous curvilinear capsulorhexis, and who didn’t develop secondary cataracts or strabismus postoperatively. Furthermore, postoperative BCVA of the affected eyes, and anisometropia influenced the stereoacuity of the patients surgically treated for unilateral developmental pediatric cataracts. ·

关键词： anisometropia developmental cataract secondary cataract stereoacuity stereopsis strabismus unilateral pediatric cataract visual acuity

Accurate Multi-Site Daily-Ahead Multi-Step PM_(2.5)Concentrations Forecasting Using Space-Shared CNN-LSTM

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Computers, Materials & Continua 2022年第3期70卷 5143-5160页

作者： Xiaorui Shao Chang soo kim Department of Information Systems Pukyong National UniversityBusan608737Korea

Accurate multi-step PM_(2.5)(particulate matter with diameters≤2.5 um)concentration prediction is critical for humankinds’health and air populationmanagement because it could provide strong evidence for ***,it is very challenging due to its randomness and *** paper proposed a novel method based on convolutional neural network(CNN)and long-short-term memory(LSTM)with a space-shared mechanism,named space-shared CNN-LSTM(SCNN-LSTM)for multi-site dailyahead multi-step PM_(2.5)forecasting with self-historical *** proposed SCNN-LSTM contains multi-channel inputs,each channel corresponding to one-site historical PM_(2.5)concentration *** which,CNN and LSTM are used to extract each site’s rich hidden feature representations in a stack ***,CNN is to extract the hidden short-time gap PM_(2.5)concentration patterns;LSTM is to mine the hidden features with long-time *** channel extracted features aremerged as the comprehensive features for future multi-step PM_(2.5)concentration ***,the space-shared mechanism is implemented by multi-loss functions to achieve space information ***,the final features are the fusion of short-time gap,long-time dependency,and space information,which enables forecasting more *** validate the proposed method’s effectiveness,the authors designed,trained,and compared it with various leading methods in terms of RMSE,MAE,MAPE,and R^(2)on four real-word PM_(2.5)data sets in Seoul,South *** massive experiments proved that the proposed method could accurately forecast multi-site multi-step PM_(2.5)concentration only using self-historical PM_(2.5)concentration time series and running ***,the proposed method obtained averaged RMSE of 8.05,MAE of 5.04,MAPE of 23.96%,and R^(2)of 0.7 for four-site daily ahead 10-hourPM_(2.5)concentration forecasting.

关键词： PM_(2.5)forecasting CNN-LSTM air quality management multi-site multi-step forecasting