• Journal of Technology Innovation
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• v.30 no.3
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• pp.1-34
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• 2022

This study examines the effect of CEO age on the value relevance of R&D which is the relationship between R&D expenditures and firm value. The value relevance of R&D expenditures is higher in companies with current older CEOs, while the relationship in companies with younger CEOs is lower than that of other companies. These results suggest that older CEOs tend to be conservative and make prudent R&D investment decisions. Because they make systematic investment decisions with rich experience, they are expected to have higher investment performance in the market. On the other hand, young CEOs choose risky investments in order to have their abilities highly evaluated in the labor market. The market places a high degree of risk on the R&D decision-making of young CEOs. Next, we analyze whether the age of the replaced CEOs affects the relationship between R&D expenditures and firm value. The result shows that the change of management increases the effect of R&D expenditure on firm value. However, in the case of being replaced by a younger CEO, this positive relationship becomes lower than that of other companies, showing results consistent with the case of the current younger CEO. The samples are analyzed by dividing them into conglomerates and non-conglomerates. In conglomerates, the age of the replaced CEOs does not affect the value relevance of R&D expenditures. Only non-conglomerates showed a negative (-) effect on the replaced younger CEOs. These results suggest that conglomerates maintain the stability of R&D management and performance so that the performance of R&D expenditures is not significantly affected by the age of the replaced CEOs. The reason is that mutual checks and support are coordinated within the group through decentralization of work and systematization of decision-making. This study shows evidence that the relationship between R&D expenditure and firm value according to the age of the replaced CEO is a phenomenon that only occurs in non-conglomerates. This phenomenon suggests that conglomerates are stably managing their R&D performance regardless of the change of CEOs or the characteristics of the CEOs.

• Journal of the Korean Orthopaedic Association
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• v.54 no.6
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• pp.528-536
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• 2019

Purpose: This study examined the effects of a weekly teriparatide on the change in vertebral compression ratio, back pain, and vertebral fracture healing in osteoporosis patients with vertebral compression fractured induced by low energy trauma. Materials and Methods: From January 2016 to December 2017, 57 patients with severe osteoporotic vertebral fractures with a T score of -3.5 or less were included in this study. The changes in the vertebral compression ratio, visual analogue scale (VAS), Oswestry disability index (ODI) for at least 6 months were examined. The morphology of bone marrow edema and the presence of intervertebral cleft, osteocalcin, and N-terminal telopeptide (NTx) were also investigated. Results: The mean compression ratio was 20% in the experimental group (teripratide group) at 3 months, and 38% in the control group. A significant difference in the compression ratio of the vertebral body over time was observed (p<0.05; t-test). A comparison of the compression ratio of the vertebral body with the follow-up duration in each group showed no significant increase in the, compression (p=0.063) in the experimental group and a significant increase in the control group (p<0.05). The mean time to reach the plateau of the compression rate was one month in the experimental group and three months in the control group. The VAS score in the experimental and control group was 0.39 and 1.07 points, respectively. The ODI score in the experimental and control group was 33.72 and 39.52, respectively. At the last follow-up radiographs, there were no cases with an intervertebral cleft (0%) in the experimental group and 1 case (2.2%) in the control group. A significant difference in the osteocalcin level was observed between the injury and 6 months after the injury (p=0.003). In addition, there was no significant difference in the NTx level between the injury and 6 months after injury (p=0.960). Conclusion: In vertebral compression fractures patients with severe osteoporosis, a weekly teriparatide can promote the union of fractures, prevent further collapse of the vertebral body, and reduce the back pain faster.

• BMB Reports
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• v.57 no.2
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• pp.110-115
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• 2024

Alterations in DNA methylation play an important pathophysiological role in the development and progression of colorectal cancer. We comprehensively profiled DNA methylation alterations in 165 Korean patients with colorectal cancer (CRC), and conducted an in-depth investigation of cancer-specific methylation patterns. Our analysis of the tumor samples revealed a significant presence of hypomethylated probes, primarily within the gene body regions; few hypermethylated sites were observed, which were mostly enriched in promoter-like and CpG island regions. The CpG Island Methylator Phenotype-High (CIMP-H) exhibited notable enrichment of microsatellite instability-high (MSI-H). Additionally, our findings indicated a significant correlation between methylation of the MLH1 gene and MSI-H status. Furthermore, we found that the CIMP-H had a higher tendency to affect the right-side of the colon tissues and was slightly more prevalent among older patients. Through our methylome profile analysis, we successfully verified the methylation patterns and clinical characteristics of Korean patients with CRC. This valuable dataset lays a strong foundation for exploring novel molecular insights and potential therapeutic targets for the treatment of CRC.

• Food Science and Preservation
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• v.30 no.5
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• pp.833-846
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• 2023

Onions are essential vegetables for Koreans' diet and have various physiological activities. However, problems arise every year due to the imbalance between production and demand. Therefore, in this study, nutritional and functional components, and antioxidant activity were analyzed for each growth period in order to utilize onions at the disposal period. Whole onions harvested before June showed higher values of general ingredients, inorganic ingredients, organic acids, spiraeoside, quercetin, total chlorophyll, and antioxidant activity than bulbs harvested in June. On the other hand, the free sugar content was higher in the bulb of the harvest season in June than in whole onions. The total thiosulfinate content was similar to that of whole onions and bulbs in the early stages of growth. In addition, as a result of comparing the flavonoid compound and antioxidant activity of each onion variety, whole onions harvested at 25 weeks were higher in content than onion bulbs harvested in June. In conclusion, onions before the harvest season in June had excellent utilization value as food. Harvesting before 21 weeks is desirable for growing onions with excellent nutritional value, while harvesting after 23 weeks is recommended for excellent functional components and antioxidant activity in onions.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.122-127
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• 2010

Purpose: The Xpress3.$cardiac^{TM}$ which is a kind of wide beam reconstruction (WBR) method developed by UltraSPECT (Haifa, Israel) enables the acquisition of at quarter time while maintaining image quality. The purpose of this study is to investigate the usefulness of WBR method for decreasing scan times and to compare to it with filtered back projection (FBP), which is the method routinely used. Materials and Methods: Phantom and clinical studies were performed. The anthropomorphic torso phantom was made on an equality with counts from patient's body. The Tl-201 concentrations in the compartments were 74 kBq (2 ${\mu}Ci$)/cc in myocardium, 11.1 kBq (0.3 ${\mu}Ci$)/cc in soft tissue, and 2.59 kBq (0.07 ${\mu}Ci$)/cc in lung. The non-gated Tl-201 myocardial perfusion SPECT data were acquired with the phantom. The former study was scanned for 50 seconds per frame with FBP method, and the latter study was acquired for 13 seconds per frame with WBR method. Using the Xeleris ver. 2.0551, full width at half maximum (FWHM) and average image contrast were compared. In clinical studies, we analyzed the 30 patients who were examined by Tl-201 gated myocardial perfusion SPECT in department of nuclear medicine at Asan Medical Center from January to April 2010. The patients were imaged at full time (50 second per frame) with FBP algorithm and again quarter-time (13 second per frame) with the WBR algorithm. Using the 4D MSPECT (4DM), Quantitative Perfusion SPECT (QPS), and Quantitative Gated SPECT (QGS) software, the summed stress score (SSS), summed rest score (SRS), summed difference score, end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) were analyzed for their correlations and statistical comparison by paired t-test. Results: As a result of the phantom study, the WBR method improved FWHM more than about 30% compared with FBP method (WBR data 5.47 mm, FBP data 7.07 mm). And the WBR method's average image contrast was also higher than FBP method's. However, in result of quantitative indices, SSS, SDS, SRS, EDV, ESV, EF, there were statistically significant differences from WBR and FBP(p<0.01). In the correlation of SSS, SDS, SRS, there were significant differences for WBR and FBP (0.18, 0.34, 0.08). But EDV, ESV, EF showed good correlation with WBR and FBP (0.88, 0.89, 0.71). Conclusion: From phantom study results, we confirmed that the WBR method reduces an acquisition time while improving an image quality compared with FBP method. However, we should consider significant differences in quantitative indices. And it needs to take an evaluation test to apply clinical study to find a cause of differences out between phantom and clinical results.

• Tuberculosis and Respiratory Diseases
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• v.66 no.3
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• pp.192-197
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• 2009

Background: Despite the benefits of home oxygen therapy in patients suffering chronic respiratory failure, previous reports in Korea revealed lower compliance to oxygen therapy and a shorter time for oxygen use than expected. However, these papers were published before oxygen therapy was covered by the national insurance system. Therefore, this study examined whether there were some changes in compliance, using time and other clinical features of home oxygen therapy after insurance coverage. Methods: This study reviewed the medical records of patients prescribed home oxygen therapy in our hospital from November 1, 2006 to September 31, 2008. The patients were interviewed either in person or by telephone to obtain information related to oxygen therapy. Results: During study period, a total 105 patients started home oxygen therapy. The mean age was 69 and 60 (57%) were male. The mean oxygen partial pressure in the arterial blood was 54.5 mmHg and oxygen saturation was 86.3%. Primary diseases that caused hypoxemia were COPD (n=64), lung cancer (n=14), Tb destroyed lung (n=12) and others. After oxygen therapy, more than 50% of patients experienced relief of their subjective dyspnea. The mean daily use of oxygen was 9.8${\pm}$7.3 hours and oxygen was not used during activity outside of their home (mean time, 5.4${\pm}$3.7 hours). Twenty four patients (36%) stopped using oxygen voluntarily 7${\pm}$4.7 months after being prescribed oxygen and showed a less severe pulmonary and right heart function. The causes of stopping were subjective symptom relief (n=11), inconvenience (n=6) and others (7). Conclusion: The prescription of home oxygen has increased since national insurance started to cover home oxygen therapy. However, the mean time for using oxygen is still shorter than expected. During activity of outside their home, patients could not use oxygen due to the absence of portable oxygen. Overall, continuous education to change the misunderstandings about oxygen therapy, more economic support from national insurance and coverage for portable oxygen are needed to extend the oxygen use time and maintain oxygen usage.

• Tuberculosis and Respiratory Diseases
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• v.47 no.4
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• pp.442-450
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• 1999

Background : Isoniazid(INH) and rifampicin(RFP) are the most effective anti-tuberculosis drugs which make the short-course chemotherapy possible. Although prescribed dosages of INH and RFP in Korea are different from those recommended by American Thoracic Society, there has been few study about pharmacokinetic profiles of INH and RFP in Korean patients who receive INH, RFP, ethambutol(EMB) and pyrazinamide(PZA) simultaneously. Methods : Among the patients with active tuberculosis from Dec. 1997 to July 1998, we selected 17 patients. After an overnight fast, patients were given INH 300mg, RFP 450mg, EMB 800mg and PZA 1500mg daily. Blood samples for the measurement of plasma INH(n=15) and RFP(n=17) level were drawn each at 0, 0.5, 1, 1.5, 2, 4, 6, 8 and 12hrs, and urine was also collected. INH and RFP level in the plasma and the urine were measured by high-performance liquid chromatography(HPLC). Pharmacokinetic parameters such as peak serum concentration(Cmax), time to reach to peak serum concentration(Tmax), half-life, elimination rate constant(Ke), total body clearance(CLtot), nonrenal clearance(CLnr), and renal clearance(CLr) were calculated. Results : 1) Pharmacokinetic parameters of INH were as follows: Cmax; $7.63{\pm}3.20{\mu}g/ml$, Tmax; $0.73{\pm}0.22hr$, half-life; $2.12{\pm}0.84hrs$, Ke; $0.83{\pm}0.15hrs^{-1}$, CLtot; $17.54{\pm}8.89L/hr$, CLnr; $14.74{\pm}8.35L/hr$, CLr; $2.79{\pm}1.31L/hr$. 2) Pharmacokinetic parameters of RFP were as follows: Cmax; $8.93{\pm}3.98{\mu}g/ml$, Tmax; $1.76{\pm}1.13hrs$, half-life; $2.27{\pm}0.54hrs$, Ke; $0.32{\pm}0.08hrs^{-1}$, CLtot; $14.63{\pm}6.60L/hr$, CLr; $1.04{\pm}0.55L/hr$, CLnr; $13.59{\pm}6.21L/hr$. 3) While the correlation between body weight and Cmax of INH was not statistically significant (r=-0.514, p value>0.05), Cmax of RFP was significantly affected by body weight of the patients(r=-0.662, p value<0.01). Conclusion : In Korean patients with tuberculosis, 300mg of INH will be sufficient to reach the ideal peak blood level even in the patients over 50kg of body weight However, 450mg of RFP will not be the adequate dose in the patients who weigh over 50~60kg.

• Tuberculosis and Respiratory Diseases
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• v.49 no.6
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• pp.740-751
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• 2000

Background : Moxifloxacin is a newly developed drug which is more potent and safe compared to previous fluoroquinolones. This drug effectively eradicates organisms such as beta-lactamase-producing or other resistant bacteria. Moxifloxacin is known to be effective in treating respiratory infections such as Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Chlamydia pneumoniaeme, Legionella spp. and Mycoplasma pneumoniae. Methods : In a multicenter, randomized, open, comparative study, the efficacy and safety of oral moxifloxacin taken 400 mg once a day and clarithromycin taken 500 mg twice daily for 7 days were compared for the treatment of Korean patients with acute exacerbations of chronic bronchitis. Results : A total of 170 patients were enrolled, and they were divided into two groups: 87 in the moxifloxacin group and 83 in the clarithromycin group. Of those enrolled, 76 (35 for bacteriologic efficacy) in the moxifloxacin group and 77 (31 for bacteriologic efficacy) in the clarithromycin group were included in the efficacy analysis. All were included in the safety analysis. Clinical success was noted in 70 (92.1%) of 76 moxifloxacin-treated patients and 71 (92.2%) of 77 clarithromycin-treated patients. Bacteriologic success rate seemed to be higher in moxifloxacin group (73.5%) than in clarithromycin group (54.8%), but statistically insignificant (p=0.098). Drug susceptibility among organisms initially isolated was higher in moxifloxacin group on Streptococcus pneumoniae, Pseudomonas aeruginosa, Klebsiella pneumoniae (p<0.001). Adverse events were reported by 12.8% of 86 patients receiving moxifloxacin and 21.7% of 83 patients receiving clarithromycin. Headache (4.7% vs 4.8%, moxifloxacin group vs clarithromycin group, respectively) and indigestion (2.3% vs 6.0%, moxifloxacin group vs clarithromycin group, respectively) were the most frequent side effects in the two groups. Conclusion : This study demonstrated that for the treatment of acute exacerbations of chronic bronchitis a 7-day course of moxifloxacin 400 mg od was clinically equivalent and microbiologically superior to clarithromycin 500 mg bid.