Publications by authors named "Kwangho Park"

Efforts to combine the advantages of homogeneous catalysts in terms of activity with the ease of separation process offered by heterogeneous catalysts continue to be actively pursued in the field of catalyst development. Heterogeneous catalysts were synthesized from Ru-MACHO organometallic compounds, recognized for their high hydrogenation catalytic activity linked to the active site of the Ru-PNP motif, through direct polymerization utilizing the Friedel-Crafts reaction. These catalysts were then applied for the conversion of greenhouse gas carbon dioxide (CO) into formate via hydrogenation, exhibited with a record-high turnover frequency of 31,700 and a productivity of 36,100 kg/(kg ⋅ d).

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Formic acid is a viable product of CO utilization. Here, we present a protocol for designing and operating a pilot-scale formic acid production plant with a 10 kg/day capacity produced via CO hydrogenation. We describe the essential process specifications required for successful operation, including prevention of corrosion and formic acid decomposition.

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Carbon capture and utilization technology has been studied for its practical ability to reduce CO emissions and enable economical chemical production. The main challenge of this technology is that a large amount of thermal energy must be provided to supply high-purity CO and purify the product. Herein, we propose a new concept called reaction swing absorption, which produces synthesis gas (syngas) with net-zero CO emission through direct electrochemical CO reduction in a newly proposed amine solution, triethylamine.

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Hyperstoichiometric (p-type) misfit-layered calcium cobaltites have been studied as components in various high-temperature electrochemical devices. Multiple studies have reported their applications or physical properties, but systematic studies on their defect structures and thermodynamic quantities are still insufficient. In this study, the oxygen nonstoichiometry and the electrical conductivity of Gd-Cu co-doped misfit cobalt oxide were measured as functions of temperature and oxygen partial pressure, along with thermodynamic quantities.

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A critical issue to tackle before successful commercialization of solid oxide fuel cells (SOFCs) can be achieved is the long-term thermal stability required for SOFCs to operate reliably without significant performance degradation despite enduring thermal cycling. In this work, the impact of thermal cycling on the durability of NiO-yttria-stabilized zirconia-based anode-supported cells is studied using three different heating/cooling rates (1, 2, and 5 °C min) as the temperature fluctuated between 400 and 700 °C. Our experiments simulate time periods when power from SOFCs is not required (e.

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We firstly introduce Er and Ga co-doped swedenborgite-structured YBaCoO (YBC) as a cathode-active material in lithium-ion batteries (LIBs), aiming at converting the phase instability of YBC at high temperatures into a strategic way of enhancing the structural stability of layered cathode-active materials. Our recent publication reported that YErBaCoGaO (YEBCG) showed excellent phase stability compared to YBC in a fuel cell operating condition. By contrast, the feasibility of the LiCoO (LCO) phase, which is derived from swedenborgite-structured YBC-based materials, as a LIB cathode-active material is investigated and the effects of co-doping with the Er and Ga ions on the structural and electrochemical properties of Li-intercalated YBC are systemically studied.

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Background: The purpose of this study was to investigate the differences in configuration and dimensions of the anterior loop of the inferior alveolar nerve (ALIAN) in patients with and without mandibular asymmetry.

Method: Preoperative computed tomography images of patients who had undergone orthognathic surgery from January 2016 to December 2018 at a single institution were analyzed. Subjects were classified into two groups as "Asymmetry group" and "Symmetry group".

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In the context of CO utilization, a number of CO conversion methods have been identified in laboratory-scale research; however, only a very few transformations have been successfully scaled up and implemented industrially. The main bottleneck in realizing industrial application of these CO conversions is the lack of industrially viable catalytic systems and the need for practically implementable process developments. In this study, a simple, highly efficient and recyclable ruthenium-grafted bisphosphine-based porous organic polymer (Ru@PP-POP) catalyst has been developed for the hydrogenation of CO to N,N-dimethylformamide, which affords a highest ever turnover number of 160 000 and an initial turnover frequency of 29 000 h in a batch process.

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Objectives: The aim of this study was to evaluate the validity of the existing classification and difficulty index of impacted mandibular third molars in clinical situations and propose a more practical classification system.

Materials And Methods: This study included 204 impacted mandibular third molars in 154 patients; panoramic x-ray images were obtained before tooth extraction. Factors including age, sex, and pattern of impaction were investigated.

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Purpose: The position changing pattern of the condyles after intraoral vertical ramus osteotomy (IVRO) on the deviated and non-deviated sides is not clearly known. This study was conducted to evaluate the changes in condylar position after IVRO in patients with facial asymmetry and to compare the deviated and non-deviated sides using computed tomography imaging.

Materials And Methods: This retrospective cohort study investigated patients with a diagnosis of mandibular prognathism with facial asymmetry who had undergone bilateral IVRO with Le Fort I osteotomy.

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Background: The relationship between the lateral deviation of chin and the upper and middle facial third asymmetry is still controversial. The purpose of this study is to evaluate the correlation of upper and middle facial third asymmetry with lateral deviation of chin using 3-dimensional computed tomography. The study was conducted on patients who underwent orthognathic surgery from January 2016 to August 2017.

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Background: Botulinum toxin injection on the masticatory muscle induces the osteopenic condition on the ipsilateral condyle. Bisphosphonate suppresses bone resorption and is used to treat osteopenic or osteoporotic condition. This study aimed to evaluate the effect of bisphosphonate administration on prevention of condylar resorption and botulinum toxin A-induced disuse osteopenia in rats.

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Background: The purpose of the present study was to investigate the differences in the position and shape of the anterior loop of the inferior alveolar nerve (ALIAN) in relation to the growth pattern of the mandibular functional subunit.

Methods: The study was conducted on 56 patients among those who had undergone orthognathic surgery at the Gangnam Severance Hospital between January 2010 and December 2015. Preoperative computerized tomography (CT) images were analyzed using the Simplant OMS software (ver.

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Objectives: The objective of this study was to analyze 11 cases of subcutaneous emphysema associated with dental procedures from a single hospital and discuss approaches for accurate diagnosis and treatment of the condition.

Materials And Methods: The medical records of 11 patients who were treated for subcutaneous emphysema related to dental procedures between January 2009 and April 2017 were analyzed retrospectively. Patients with subcutaneous emphysema within the facial area or that spread to the neck and beyond, including the facial region, were assigned to two groups and compared in terms of age, sex, and durations of antibiotic use, hospitalization, and follow-up until improvement.

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Objectives: The aim of this study was to reveal how collagenases (matrix metalloproteinase [MMP]-1, 8, 13) and tissue inhibitor of metalloproteinase 1 (TIMP-1) are expressed in immunohistochemistry of retrodiscal tissue in temporomandibular joint disorder patients.

Materials And Methods: This study was conducted on 39 patients who underwent discoplasty or discectomy. Immunohistochemical staining was undertaken and expression levels of MMP-1, 8, 13, and TIMP-1 were evaluated.

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Objective: The aim of this study was to analyze risk factors and establish a prediction model for temporomandibular joint (TMJ) disk perforation by constructing a nomogram.

Study Design: The study included a total of 282 joints in 274 patients. All patients underwent open TMJ surgery after obtaining magnetic resonance imaging (MRI), from 2005 to 2015.

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β-Hydroxy esters are considered as potential building blocks for the production of fine chemicals and potential drug molecules in various industries. Developing an efficient and recyclable catalyst for the synthesis of β-hydroxy esters is challenging. Here we report the first ionic-liquid-based heterogenized cobalt catalyst, [imidazolium-CTF][Co(CO)], for the direct ring-opening carbonylation of propylene oxide to methyl 3-hydroxybutyrate (MHB) with 86% selectivity (>99% conversion).

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Background: Implants with deep thread depth have been developed for the purpose of increasing total implant surface area. However, effects of implant thread depth remain controversial. The aim of this study is to examine effects of thread depth on peri-implant tissues in terms of bone-implant contact (BIC), bone-implant volume (BIV), and hard and soft tissue dimensions using comprehensive analyses, including microcomputed tomography (micro-CT).

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Objective: To evaluate the volume and position of the temporomandibular joint structures, specifically the glenoid fossa and the condylar head, in patients with facial asymmetry.

Study Design: Fifty-six adult patients were divided into two groups-asymmetry group and control group-based on the severity of the mandibular asymmetry, as seen on their orthopantomograms. The volumes and positions of the bilateral temporomandibular joint components were measured by using computed tomography images and a three-dimensional analysis program.

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Necrotizing sialometaplasia usually heals within 4 to 10 weeks with conservative treatment, and rarely recurs. When necrotizing sialometaplasia is present on the hard palate it may occur unilaterally or bilaterally. In this case, necrotizing ulceration occurred on the left hard palate of a 36-year-old woman after root canal treatment of the upper left first premolar under local anesthesia.

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We describe our experience with conservative condylectomy for the correction of facial asymmetry in five patients with osteochondroma of the mandibular condyle. All five patients presented with malocclusion and facial asymmetry, which are common clinical findings of osteochondroma involving the mandibular condyle. We performed conservative condylectomy without additional orthognathic surgery for all five patients, preserving the vertical height of the condylar process as much as possible.

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Objectives: The aim of this animal study was to examine the effects of thread size in the implant neck area on peri-implant tissues in terms of BIC and hard- and soft-tissue dimensions.

Materials And Methods: Six Beagle dogs received experimental implants in the mandible 3 month after the removal of premolars and first molars (P2, P3, P4, and M1). Two different types of implants were installed in each animal: Anyone microthread(®) as Group 1 and Anyone(®) as Group 2.

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A heterogenized catalyst on a highly porous covalent triazine framework was synthesized and characterized to have a coordination environment similar to that of its homogeneous counterpart. The catalyst efficiently converted CO2 into formate through hydrogenation with a turnover number of 5000 after 2 h and an initial turnover frequency of up to 5300 h(-1) ; both of these values are the highest reported to date for a heterogeneous catalyst, which makes it attractive toward industrial application. Furthermore, the synthesized catalyst was found to be stable in air and was recycled by simple filtration without significant loss of catalytic activity.

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Introduction: We report a case of successful autotransplantation of a premolar impacted with a dentigerous cyst and transplanted with collagen plugs for initial support.

Methods: An 18-year-old man had an impacted premolar accompanied with a large dentigerous cyst. The tooth was extracted surgically and transplanted to an edentulous alveolar ridge, and a collagen sponge was inserted to ensure proper healing and initial support.

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Objectives: The purpose of this retrospective study is to find the differentiating characteristics of cystic and cystic-appearing lesions that involve the impacted mandibular third molar by analyzing panoramic radiographs and computed tomography images, and to aid the preoperative diagnosis.

Materials And Methods: Eighty-one patients who had a mandibular cystic or cystic-appearing lesion that involved impacted mandibular third molar and underwent cyst enucleation were included in the study. The preoperative panoramic radiograph and computed tomography findings were analyzed in accordance to the histopathologic type.

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