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High salt intake results in various harmful effects on human health including hypertension, cardiovascular disease, and reduced bone density. Despite this, there are very few studies in the literature that have investigated the association between sodium intake and osteoarthritis (OA). Therefore, we aimed to explore these associations in a Korean population.This study used cross-sectional data from adult subjects aged 50-75 years from two consecutive periods of the Korean National Health and Nutrition Examination Survey V-VII (2010-2011 and 2014-2016). The estimated 24-hour urinary sodium excretion (24HUNa) was used as a surrogate marker of salt intake. In the 2010-2011 dataset, knee OA (KOA) was defined as the presence of the radiographic features of OA and knee pain. The association between KOA and salt intake was analysed using univariable and multivariable logistic regression methods. For the sensitivity analysis, the same procedures were conducted on subjects with self-reported OA (SR-OA) with knee pain in the 2010-2011 dataset and any site SR-OA in the 2014-2016 dataset.Subjects with KOA had significantly lower energy intake, but higher 24HUNa than those without KOA. The restricted cubic spline plots demonstrated a J-shaped distribution between 24HUNa and prevalent KOA. When 24HUNa was stratified into five groups (2, 2-3, 3-4, 4-5 and ≥5 g/day), subjects with high sodium intake (≥5 g/day) had a higher risk of KOA (odds ratio [OR] = 1.64, 95% confidence interval [CI] 1.03-2.62) compared to the reference group (3-4 g/day) after adjusting for covariates. The sensitivity analysis based on SR-OA with knee pain showed that high sodium intake was also significantly associated with increased prevalence of OA (OR = 1.84, 95% CI 1.10-3.10) compared with the reference group. Regarding SR-OA at any site in the 2014-2016 dataset, estimated 24HUNa showed a significantly positive association with the presence of SR-OA after adjusting for potential confounders.This nationwide Korean representative study showed a significant association between symptomatic KOA and high sodium intake (≥5 g/day). Avoidance of a diet high in salt might be beneficial as a non-pharmacologic therapy for OA.

Background The neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) are used as a diagnostic marker, disease activity marker, and prognostic marker in patients with Crohn’s disease and ulcerative colitis. We aimed to investigate the NLR and PLR as a marker of inflammation and prognostic biomarker in intestinal Behçet’s disease (BD). Methods A total of 1712 diagnostic tests with 621 intestinal BD patients who underwent both blood examination and endoscopic examination at the Inflammatory Bowel Disease Clinic of Severance Hospital, Seoul, Korea between March 2005 to November 2020 were analyzed in our study. We analyzed to identify the independent risk factors of the clinical remission (CR) and endoscopic remission (ER). Moreover, for 435 patients who underwent a series of blood and endoscopic examination, we performed Kaplan-Meier (K-M) analyses to identify the NLR and PLR as a marker of prognosis in intestinal BD. Results The NLR levels were higher in non-CR group compared to CR group (3.3±2.7 vs. 2.0±1.2, p Conclusion The NLR and PLR were higher in patients with active intestinal BD compared to those with inactive intestinal BD. And the NLR and PLR showed a promising role as marker for prediction of disease prognosis. Therefore, the NLR and PLR might be effective, readily available, and low-cost biomarkers for inflammation in intestinal BD patients.

BackgroundBehcet’s disease (BD) is a systemic vasculitis with multiorgan involvement.ObjectivesTo compare the risk of all-cause and cause specific mortality among patients with BD compared to general populationMethodsUsing the 2002-2017 Korea National Health Insurance database, we conducted a cohort study among BD patients compared to general population matched on age and sex at a 1:5 ratio. The primary outcome was death of any cause, and the secondary outcomes were cause-specific mortality for top 5 causes of death. Cox proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs), comparing BD patients versus general population.ResultsThe PS-matched study cohort (mean age 42.1 years; 32.0% male) included 32288 BD patients and 161440 controls. During a mean follow-up of 9.6 years, 2214 deaths occurred. The HR [95%] for all-cause mortality was 10.6 [9.6-11.6]. The Top 5 causes of death derived from malignancy, cardiovascular disease, infection, respiratory disease, and injury: the HR [95%] for mortality from these causes were 8.5 [7.2-10.1], 10.8 [8.6-13.6], 14.6 [8.1-26.3], 12.0 [8.5-17.0], and 8.0 [5.0-13.0], respectively.ConclusionThis population-based cohort study warns exceptionally heavy burden of the disease showing approximately 10 times higher mortality of BD patients compared to general population. In line with this, risk of cause specific mortality was also significantly higher among the BD patients, for 5 top causes of death.Disclosure of InterestsNone declared

BackgroundGout is associated with an increased risk of cardiovascular (CV) disease.ObjectivesTo update comparative CV safety of febuxostat versus allopurinol among patients with goutMethodsUsing the 2011-2019 Korea National Health Insurance database, we conducted a cohort study comparing gout patients initiating febuxostat versus allopurinol, with study participants matched on a propensity score (PS) for>60 covariates at a 1:1 ratio. The primary outcome was composite CV outcome of myocardial infarction, coronary revascularization, and stroke. Secondary outcomes were CV and all-cause mortalities in addition to individual components of the primary outcome. Cox proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs), comparing febuxostat versus allopurinol initiators.ResultsWe included 160,930 febuxostat users PS-matched on 160,930 allopurinol users (mean age 59.3 years, 79.6% male). During a mean follow-up of 250 days, the incidence rate of the primary outcome was 2.27 and 2.06 per 100 person-years for allopurinol and febuxostat users respectively, with the PS-matched HR [95% CI] of 1.03 [0.95-1.12]. Analysis on secondary outcomes also showed a similar result except for all-cause mortality with a significantly reduced risk among febuxostat users with a PS-matched HR [95% CI] of 0.84 [0.78-0.91] (Table 1).Table 1.Comparative cardiovascular safety between febuxostat and allopurinolFebuxostat N = 160,930Allopurinol (Ref) N= 160,930HR (95% CI)EventsPYaIR [95% CI]EventsPYaIR(95% CI]Composite CV endpoint2635128,1932.06 [1.98-2.13]2,09992,5122.27 [2.17-2.37]1.03 [0.95-1.12]MI468129,8730.36 [0.33-0.39]34193,8080.36 [0.33-0.40]1.13 [0.91-1.39]Coronary revascularization1085129,2330.84 [0.79-0.89]85693,2930.92 [0.86-0.98]1.10 [0.96-1.26]Stroke or TIA1490129,1631.15 [1.10-1.21]1,18793,2521.27 [1.20-1.35]0.99 [0.90-1.10]Death2558130,1761.97 [1.89-2.04]2,20194,0072.34 [2.24-2.44]0.84 [0.78-0.91]aIR is per 100 person-years. IR=incidence rate, HR=hazard ratio, CI=confidence interval, MI=myocardial infarction, PY=person-years, TIA=transient ischemic attackConclusionThis large population-based cohort study showed a similar CV safety profile between febuxostat and allopurinol users but found a 16% reduced all-cause mortality among febuxostat users compared to allopurinol, primarily derived from non-CV death reduction.Disclosure of InterestsNone declared

BackgroundThe increased prevalence of rheumatoid arthritis (RA) in women has led to studies exploring how female reproductive factors affect disease outcomes in women RA. While a few studies have investigated how early menopause (EM) affects RA outcomes, they had relatively small sample size and have shown inconsistent results [1, 2]. Moreover, none has evaluated the association between age at menopause and longitudinal changes in validated disease activity indices or patient-reported outcomes (PROs) of RA.ObjectivesWe aimed to assess the differences in clinical outcomes between RA patients with EM (age at menopause MethodsA total of 2,878 postmenopausal women with RA were included from the Korean Observational Study Network for Arthritis, a nationwide prospective RA cohort of Korea. Each patient was examined at baseline and for 5 consecutive years using the simplified disease activity index (SDAI), health assessment questionnaire-disability index (HAQ-DI), and other PROs. Among patients with a baseline SDAI >11, generalized estimating equation (GEE) analyses were performed to evaluate the impact of EM on longitudinal changes in RA activity and PROs during follow-up.ResultsThe EM group (N=437) was younger than the UM group (N=2,441) [58.0±9.5 vs. 60.8±8.0 years, pConclusionRA patients with EM demonstrate higher disease activity and poorer health-related quality of life. EM significantly affects longitudinal changes in disease activity and PROs in RA.References[1]Pikwer M, Nilsson JA, Bergstrom U, et al. Early menopause and severity of rheumatoid arthritis in women older than 45 years. Arthritis Res Ther. 2012 Aug; 14(4):R190.[2]Wong LE, Huang WT, Pope JE, et al. Effect of age at menopause on disease presentation in early rheumatoid arthritis: results from the Canadian Early Arthritis Cohort. Arthritis Care Res (Hoboken). 2015 May; 67(5):616-623.Table 1.Longitudinal analysis of predictors of the SDAI, HAQ-DI, and EQ-5D utility value over time using a GEE model among patients with a baseline SDAI >11OutcomeIndependent variablesRegression coefficient (β) (95% CI)PSDAIAge0.013 (-0.024-0.049)0.503RA duration0.084 (0.046-0.122)Baseline SDAI0.580 (0.531-0.630)Biologic use0.196 (-0.924-1.315)0.732Early menopause1.265 (0.412-2.117)0.004Follow-up time-1.806 (-1.964--1.647)HAQ-DIAge0.007 (0.004-0.009)RA duration0.011 (0.009-0.014)Baseline HAQ-DI0.674 (0.638-0.711)Biologic use0.044 (-0.033-0.122)0.264Early menopause0.092 (0.030-0.154)0.003Follow-up time-0.004 (-0.016-0.007)0.457EQ-5DAge-0.002 (-0.003--0.000)0.007RA duration-0.003 (-0.004--0.002)Baseline EQ-5D utility value0.532 (0.492-0.572)Biologic use-0.012 (-0.045-0.021)0.489Early menopause-0.033 (-0.059--0.006)0.016Follow-up time0.010 (0.005-0.015)Disclosure of InterestsNone declared

Background:Interstitial lung disease (ILD) is a severe extra-articular manifestation of rheumatoid arthritis (RA). However, there are few prospective studies for the natural course of lung physiology in most patients with RA-ILD.Objectives:To assess the natural course of lung physiology of RA-ILD and the relation between arthritis activity and pulmonary physiology in patients with RA-ILD.Methods:The KOrean Rheumatoid Arthritis ILd (KORAIL) cohort is the prospective observational cohort and aims to investigate the natural course of RAILD. Based on either 1987 or 2020 ACR criteria, patients diagnosed with RA and ILD based on CT scan were recruited from six tertiary medical hospitals in Korea since January 2015. RA disease activity was assessed using swollen and tender joint count by treating physician, inflammatory markers including CRP and ESR, and patient’s global assessment annually. Pulmonary function tests (PFT), including FVC, FEV1, DLCO, and chest CT scan, were conducted annually.Results:We analyzed 163 patients at baseline (V1), 141 at 1-year (V2), 122 at 2-year (V3), and 88 at 3-year follow-up (V4). The mean (±SD) duration since RA diagnosis and since ILD diagnosis was 7.6±8.0 and 2.7±3.1 years, respectively. The female to male ratio was about 2:1, and 58.9% of patients (n=96) were 65 years old or older. Only two patients were negative for RF and anti-CCP; 98.7% of patients (n=161/163) were positive for RF (n=143, 87.7%) or anti-CCP antibody (n=154, 94.5%). At enrollment, one-hundred-nine patients (66.9%) had FVC ≥80 % of predicted. Twenty-five patients (15.3%) showed FEV1/FVC≥0.7, of which seventeen patients, only ten percent of a total cohort (10.4%), had FVC ≥80% of predicted, which corresponds to the obstructive pattern. Proportion of patients showed a ≥10-point decline from the enrollment in FVC of the predicted value were around 10% at every year (Table 1). The proportion of patients with a relative decline of ≥10% from the enrollment in FVC predicted was increased every year because of cumulation. The proportion of patients with a relative decline of ≥10% from the previous visit in FVC predicted was also around 10-15% every year. Proportions of patients with 55% or more DLco % pred. has been decreased annually; 78.5% (n=128/158) at V1, 72.9% (n=105/139) at V2, 68.7% (n=90/117) at V3, and 56.6% (n=56/85) at V4. Patients with a relative decline of ≥10% from the enrollment in DLco predicted was 38 (27.5 %) at V2 and 37 (31.9%) at V3. Patients with a relative decline of ≥10% from the previous visit in DLco predicted was 29 (25.2%) at V3. Of note, thirty patients (21.7%) showed a relative 10% or more increase from enrollment in DLco predicted at V2, and so did 30 patients (25.9%) at V3.Table 1.The analysis of forced vital capacity (FVC) in KORIL cohortV1 (enrollment)V2 (1-year)V3 (2-year)V4 (3-year)FVC (mL), mean±SD2549.5 ± 743.32479.5±764.42435.8 ± 742.82405.7 ± 731.2FVC % of predicted, mean±SD84.70 ± 16.7484.7±18.184.3 ± 17.683.1 ± 19.1Rate of FVC decline, mL·year-1 (95% CI)--14 (-49, 21)-62 (-104, -21)-A 10-point decline from V1 in predicted FVC value, n (%)-10 (7.1)16 (13.3)8 (9.4)Relative decline of 10% from V1 in predicted FVC value, n (%)-17 (12.1)23 (18.9)17 (19.3)Relative decline of 10% from the previous visit in predicted FVC value, n (%)-17 (12.1)17 (14.2)13 (15.3)Conclusion:Annually, about 10-15% of patients experience a relative ≥10% decline from the previous visit in FVC predicted value in RA-ILD.Acknowledgements:This work was supported by the Korea Health Technology R&D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health and Welfare, Republic of Korea (grant no.HI14C1277).Disclosure of Interests:None declared

RORγt, a truncated isoform of retinoic acid receptor-related orphan receptor gamma (RORγ), is a transcription factor involved in Th17 cell differentiation. It is expressed in a few distinct types of immune cells and described as the master regulator of Th17 cytokine expression1. RORγ has identical ligand-binding domains as RORγt2; consequently, compounds targeting RORγ are also expected to modulate Th17 cell activity. This article is protected by copyright. All rights reserved.

BACKGROUND Use of human milk is recommended for low birth weight (VLBW) infants, but must be safety fortified with sterile liquid fortifiers to be nutritionally sufficient. Due to clinical concern for a high incidence of metabolic acidosis among VLBW infants fed human milk fortified with acidified liquid human milk fortifier (ALHMF), we aimed to retrospectively compare the outcomes of infants fed ALHMF to those fortified with non-acidified liquid HMF (NLHMF). METHODS Medical records of VLBW neonates admitted to our institution's neonatal intensive care unit from July 1st, 2013 to June 30th, 2014 were reviewed. 129 patients were included in the study, 61 of which received ALHMF and 68 received NLHMF. Metabolic, nutritional and clinical outcomes, including growth, were compared between the two cohorts. RESULTS Of the infants who received ALHMF, 70.5% developed metabolic acidosis compared to only 11.8% in the NLHMF group (p

Introduction Anti-tachycardia pacing (ATP) therapy is an important treatment for current ICD termination of ventricular arrhythmia (VA). But there was concern about excessive frequency and voltage can cause arrhythmia, pain and damage. Optogenetic allowed modulation of electrical excitation with light in myocardium over-expressing light-sensitive protein, and optical illumination developed a non-contact and pain-free approach to research and treatment of cardiac disorder. Purpose Explore the effects of optogenetic termination and electric termination of myocardial infarction VA in vivo. Methods Rats (N=10) accepted jugular vein injection with 1×1012 vector genomes of (AAV-CAG-hChR2(H134R)-mcherry) to achieve cardiac transgenic expression of light sensitive protein Channelrhodopsin-2 (ChR2). After thoracotomy, myocardial infarction was induced by ligation of the left anterior descending coronary artery, and then VA was induced by electrical burst stimulation (10 v, 50 Hz, 2 s). Before the myocardial infarction operation, every heart was illuminated by 473 nm laser or electrical stimulated on the right ventricle in a train of 30 pulses at 8 HZ to test the threshold of light intensity or electrical pacing voltage. The VA termination process during 20 s after burst stimulation was investigated in different performance: optical termination, 1 s constant illumination repeated in 4 episodes with 1 s interval (470 nm, 20 times threshold intensity); electrical termination, ATP in 8 pulses of 8hz with 2ms duration in 4 times pacing threshold; natural recovery from VA, without optical or electrical intervention. Recovery time was defined as the time from the end of the burst stimulation to the recovery of sinus rhythm, and the termination rate was the percentage of sinus rhythm recovery among 11s after the end of burst stimulation with or without any intervention. Results We analyzed the recovery time and the termination rate (N=10, n=127 episodes per mode). The sequence of recovery time was optical termination (7.328±0.3623 s) < electric termination (10.31±0.4482 s) < natural recovery (12.97±0.3834 s) (figure D). We confirmed that the termination rate of optical illumination (86.14±4.145%) was higher than those of ATP (63.5±6.371%) and natural recovery (47.71±5.476%) (figure E), and there was no significant difference between the last two process (one-way of ANOVA; p=0.124). Comparison of three modes Conclusions Optogenetic manipulation shortened the recovery time and increased the termination rate in myocardial infarction ventricular arrhythmia, which may provide a potential approach for translational arrhythmia therapy. Acknowledgement/Funding The national natural science foundation of China (81772044)

Background The main path of sepsis-induced cardiomyopathy is the loss of endothelial barrier function. Neuregulin-1 (NRG-1) has beneficial effects on endothelial function. Purpose To investigate the effect of NRG-1 treatment on the protection of cardiac endothelial cells and the changes of RhoA/ROCK signaling in sepsis. Methods Rats were randomly divided into three groups: sham, LPS, and NRG-1. After successful induction of sepsis by lipopolysaccharide (LPS, 10mg/kg), rats were administered either a vehicle or recombinant human neuregulin-1 (rhNRG-1, 10μg/kg/d) for one or two days. We recorded their survival rate at 48h after sepsis. Hemodynamic methods were performed to assess cardiac function. We used immunofluorescence assay to detect von Willebrand Factor (vWF). Intercellular adhesion molecule-1 (ICAM-1) and vascular endothelial growth factor (VEGF)levels in serum were measured by enzyme-linked immunosorbent assay (ELISA), and serum nitric oxide (NO) was detected by reductase method. We used transmission electron microscopy to observe changes in myocardial ultrastructure and western blot to assess expression of RhoA and ROCK1 protein. Results Sepsis impaired endothelial function manifested by increased ICAM-1, NO and VEGF levels in serum, NRG-1 treatment could significantly alleviate these increase (P Levels of endothelial biomarker in serum ICAM-1 (pg/ml) VEGF (pg/ml) NO (pg/ml) Sham 24h 1564.74±94.41 0.84±0.28 203.27±1.81 Sham 48h 322.92±7.92 1.78±0.61 6.57±0.38 LPS 24h 5139.85±284.15† 3.11±0.04† 679.05±78.59† LPS 48h 950.41±25.23†‡ 4.65±0.30† 180.40±30.08†‡ NRG 24h 2772.18±164.45§ 0.30±0.04§ 355.14±23.41§ NRG 48h 578.57±28.97§‡ 1.02±0.45§ 104.67±2.13§‡ †p Effect of NRG-1 on endothelial cells Conclusions NRG-1 could alleviate endothelial injury in sepsis by strengthening the barrier function of vascular, reducing the secretion of endothelial-related biomarkers and inhibiting oxidative stress, thus improving cardiac function and survival rate, these effects may base on RhoA/ROCK signaling pathway. These may contribute to reverse the impaired endothelial cells in sepsis in the future. Acknowledgement/Funding The national natural science foundation of China (81772044)

BACKGROUND: Oral semaglutide is the first oral formulation of a glucagon-like peptide-1 (GLP-1) receptor agonist developed for the treatment of type 2 diabetes. We aimed to compare the efficacy and safety of flexible dose adjustments of oral semaglutide with sitagliptin 100 mg. METHODS: In this 52-week, multicentre, randomised, open-label, phase 3a trial, we recruited patients with type 2 diabetes from 81 sites in ten countries. Patients were eligible if they were aged 18 years or older (19 years or older in South Korea), had type 2 diabetes (diagnosed ≥90 days before screening), HbA1c of 7·5-9·5% (58-80 mmol/mol), and were inadequately controlled on stable daily doses of one or two oral glucose-lowering drugs (for 90 days or more before screening). Participants were randomly assigned (1:1) by use of an interactive web-response system, stratified by background glucose-lowering medication at screening, to oral semaglutide with flexible dose adjustments to 3, 7, or 14 mg once daily or sitagliptin 100 mg once daily. To approximate treatment individualisation in clinical practice, oral semaglutide dose could be adjusted on the basis of prespecified HbA1c and tolerability criteria. Two efficacy-related estimands were prespecified: treatment policy (regardless of treatment discontinuation or use of rescue medication) and trial product (on treatment and without use of rescue medication) for participants randomly assigned to treatment. The primary endpoint was achievement of HbA1c of less than 7% (53 mmol/mol) at week 52 and the confirmatory secondary efficacy endpoint was change in bodyweight from baseline to week 52. Safety was assessed in all participants who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, number NCT02849080, and European Clinical Trials Database, EudraCT number 2015-005593-38, and an open-label extension is ongoing. FINDINGS: Between Sept 20, 2016, and Feb 7, 2017, of 804 patients assessed for eligibility, 504 were eligible and randomly assigned to oral semaglutide (n=253) or sitagliptin (n=251). Most participants were male (285 [57%] of 504) with a mean age of 57·4 years (SD 9·9). All participants were given at least one dose of their allocated study drug except for one participant in the sitagliptin group. From a mean baseline HbA1c of 8·3% (SD 0·6%; 67 mmol/mol [SD 6·4]), a greater proportion of participants achieved an HbA1c of less than 7% with oral semaglutide than did with sitagliptin (treatment policy estimand: 58% [134 of 230] vs 25% [60 of 238]; and trial product estimand: 63% [123 of 196] vs 28% [52 of 184]). The odds of achieving an HbA1c of less than 7% was significantly better with oral semaglutide than sitagliptin (treatment policy estimand: odds ratio [OR] 4·40, 95% CI 2·89-6·70, p

Stress-related mucosal disease (SRMD), or stress ulceration, is a group of conditions ranging from stress-related superficial gastric mucosal damage to deep gastric ulcers that are primarily correlated with mucosal ischemia, and pharmacologic interventions that optimize tissue perfusion or preserve defensive mucus aim to decrease the occurrence of conditions, such as gastric acidity, or enhance gastric defenses. However, the identification of multifactorial pathogenesis may be effective in preventing SMRD, and the use of stress prophylaxis is generally preferred. Since threonine is a component in the polymerization and synthesis of gastric mucin and possibly enhanced defense actions and lignin may provide structural support for defense and antioxidative function, we hypothesized that dietary intake of threonine and/or lignin can enhance defense against SRMD. The water immersion-restraint stress (WIRS) was used in rats and additional groups were pretreated with threonine alone or the combination of threonine and lignin. Based on gross and microscopic evaluations, threonine alone or the combination of threonine and lignin, a natural antioxidant, significantly reduced the development of SRMD (P0.05). According to molecular explorations, the levels of inflammatory mediators, such as interleukin (IL)-8, IL-6, IL-1β, inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), and interferon gamma (IFN-γ), all of which are mediators that play a significant role in controlling WIRS, significantly decreased in the groups pretreated with either threonine alone or the combination of threonine and lignin (P0.01). WIRS significantly increased apoptosis in the stomach. However, the apoptotic index significantly decreased with threonine pretreatment. According to periodic acid Schiff staining results, the expression of gastric mucin was significantly preserved in groups pretreated with threonine but remarkedly decreased in the WIRS group. The gastric heme oxygenase-1 levels significantly increased in the group treated with threonine. In conclusion, the dietary intake of threonine or the combination of threonine and lignin is effective in preventing SRMD.

Background:Interstitial lung disease (ILD) is a severe extra-articular manifestation of rheumatoid arthritis (RA). However, the effect of RA treatment on the course of ILD is not yet known.Objectives:To assess the effect of RA treatment on the course of lung physiology of RA-focusing on biologic DMARDs treatment.Methods:The Korean Rheumatoid Arthritis ILd (KORAIL) cohort is the prospective observational cohort and aims to investigate the natural course of RAILD. Based on either 1987 or 2020 ACR criteria, patients diagnosed with RA and ILD based on CT scan were recruited from six tertiary medical hospitals in Korea since January 2015. RA disease activity was assessed using disease activity (DAS)28-ESR and CRP, annually. Pulmonary function tests (PFT), including FVC and DLCO were conducted annually. In the current study, we analyzed patients who completed a 2-years follow-up or had died during those terms till October 2020. They classified patients into three groups: patients treated with abatacept ≥24 weeks ever (Group 1), those with other bDAMRDs ≥24 weeks ever (Group 2), and those without any bDMARDs or with bDMARDs Results:Of a total of 125 patients who completed 2-year follow-up, 21 patients were classified as Group 1, 26 for Group 2, and 78 for Group 3. The mean age or the number of patients with ≥ 65-year-old was comparable between groups(Table 1). The mean duration since RA diagnosis was shorter in Group 3, but that since ILD diagnosis was comparable. DAS28-ESR score was comparable between Group 1 and 2 at enrollment, so was in 1-year-follow-up (p=0.75) and 2-year-follow-up (p=1.00). FVC and % of the predicted value in FVC, FEV1, and DLco were also comparable among the three groups at enrollment. The numbers of patients with ≥10-point decline in % of FVC predicted was 2 (10.0%) for Group 1, 1 (3.8%) for Group 2, 3 (3.9%) for Group3 during the first 1-year follow-up, and 3 (15.8%), 3 (11.5%), 10 (14.1%) during the last 1-year follow up. The percent of FVC predicted was 81.6 ± 17.5 %, 87.4 ± 17.9 %, 85.2 ± 17.7 % for Group 1,2 and 3, respectively, at 1-year-follow-up, and 79.5 ± 18.8 %, 89.0 ± 16.8 %, 83.5 ± 17.3 % at 2-year-follow-up. (Figure 1A). The percent of DLco predicted was 75.5 ± 23.4 %, 66.7 ± 18.1 %, 67.5 ± 16.7 % for Group 1,2 and 3, respectively, at 1-year-follow-up, and 74.0 ± 23.7 %, 69.1 ± 18.9 %, 67.0 ± 18.5 % at 1-year-follow-up (Figure 1B).Conclusion:Treatment of bDMARDs did not exacerbate FVC than without bDMARDs treatment and mitigated the decline of DLCO compared to without bDMARDs treatment during 2-year-follow-up.Table 1.Clinical characteristics at enrollment (V1)TotalGroup 1.Group 2.Group 3.PN125212678Age at enrollment65.9±8.266.0±8.863.9±8.066.6±8.10.3465, n (%)72 (57.6)13 (61.9)11 (42.3)48 (61.5)0.21Female, n (%)89 (71.2)16 (76.2)17 (65.4)56 (71.8)0.71RA duration, years8.0±8.49.6±6.69.2±9.07.2±8.60.05ILD duration, years3.0±3.33.8±3.73.8±3.52.5±3.10.10BMI, kg/m224.1±3.123.8±3.724.8±2.923.9±3.00.39Ever-smoker1855180.57RF positive, n (%)111 (88.8)19 (90.5)22 (84.6)70 (89.7)0.72Anti-CCP positive, n (%)119 (95.2)20 (95.2)25 (96.2)74 (94.9)1.00Arthritis activityDAS28-ESR4.0 ± 1.44.1 ± 1.14.3 ± 1.83.8 ± 1.40.60*DAS28-CRP3.1 ± 1.43.2 ± 1.23.4 ± 1.63.0 ± 1.40.76*HAQ-DI0.70 ± 0.760.64 ± 0.490.82 ± 0.820.67 ± 0.800.28*Pulmonary function testFVC, ml2522.5 ± 765.42406.2 ± 772.62617.3 ± 965.22522.2 ± 692.30.65FVC, % of pred.84.6 ± 16.980.9 ± 17.786.12 ± 17.8285.08 ± 16.50.53FEV1, % of pred.92.4 ± 21.492.0 ± 24.890.6 ± 22.193.0 ± 20.40.88DLco, % of pred.71.5 ± 19.772.3 ± 26.769.1 ± 16.472.0 ± 18.70.80Figure 1.Acknowledgements:This research was supported by Bristol Myers Squibb Inc.Disclosure of Interests:Sung Hae Chang: None declared, Ji Sung Lee: None declared, Jeong Seok Lee: None declared, Chan Ho Park: None declared, Min Uk Kim: None declared, You-Jung Ha: None declared, Eun Ha Kang: None declared, Yeon Ah Lee: None declared, Yongbeom Park: None declared, Jung-Yoon Choe: None declared, Eun Young Lee Grant/research support from: Bristol Myers Squibb Inc.

Background:Interstitial lung disease (ILD) is a severe extra-articular manifestation of rheumatoid arthritis (RA). However, the effect of RA disease activity on the course of ILD is not yet known.Objectives:To assess the natural course of lung physiology of RA-ILD and the relation between arthritis activity and pulmonary physiology in patients with RA-ILD.Methods:The Korean Rheumatoid Arthritis ILd (KORAIL) cohort is the prospective observational cohort and aims to investigate the natural course of RAILD. Based on either 1987 or 2020 ACR criteria, patients diagnosed with RA and ILD based on CT scan were recruited from six tertiary medical hospitals in Korea since January 2015. RA disease activity was assessed using disease activity (DAS)28-ESR and CRP, annually. Pulmonary function tests (PFT), including FVC and DLCO were conducted annually. According to the transition of DAS28-ESR status, we classified patients into four groups: Group A. persistent remission or low disease activity, Group B. improvement, Group C. worsening, Group D. persistent moderate to high disease activity.Results:We analyzed 143 patients who completed a 2-year follow-up (visit 2) or had died with available PFT results at least twice. Mean duration since RA diagnosis and since ILD diagnosis was 7.6±8.0 and 2.7±3.1 years, respectively. Twenty-four patients were Group A, 33 Group B, 10 Group C and 30 Group D. The mean of FVC (mL) and % of the predicted value in FVC was significantly lower in Group D than in other groups (Table 1). The annual rate of decline in FVC was -42 (95% CI -93~10) mL·year-1 in Group B while -113 (95% CI -206~-21) mL·year-1 in Group C (Figure 1A). The annual decline rate in Group C was further exaggerated in patients with ≥ 80% of FVC predicted (-141, 95% CI -251~-32 mL·year-1). During two years of follow-up, patients ever experienced a relative decline of ≥10% from the enrollment in FVC predicted was 27.3%(n-9/33) in Group B whereas 30.0% (3/10) in Group C. The annual rate of decline in % of DLco predicted value was also the largest in Group C (-4.6 %·year-1, 95%CI -8.5~-0.7), which further exaggerated in patients with ≥ 80% of FVC predicted (-4.9%·year-1, 95 %CI -8.3~-1.5, Figure 1B). Of note, about half of patients with maintained not only low disease activity (Group A) but also moderate to severe disease activity (Group D) improved in DLco at least 10% or more from the enrollment of DLco predicted value (Group A: 54.2%, n=13/24, Group D: 46.7%, n=14/30).Conclusion:RA disease activity is associated with the change of lung physiology in patients with RA-ILD; worsening disease activity associated with a further decrease of annual change in FVC and maintaining low disease activity associated with a further increase of annual change in % of DLco predicted value.Table 1.The analysis of forced vital capacity (FVC) according to disease activity transition group.Group AGroup BGroup CGroup DFVC (mL), mean±SD2810.0±771.12528.8±735.32801.0±952.72048.3±575.7FVC % of predicted, mean±SD87.5±14.586.5±16.693.0±15.677.2±17.3Rate of FVC decline, mL·year-1 (95% CI)-52 (-112,7)-42 (-93,10)-113 (-206, -21)1 (-52, 54)A 10-point decline from V1 in predicted FVC value, n (%)29 (20.3)6 (25.0)6 (18.2)3 (30.0)Relative decline of 10% from the enrollment in predicted FVC value, n (%)35 (24.5)5 (20.8)9 (27.3)3 (30.0)Figure 1.The annual change of pulmonary physiology according to disease activity transition group.Acknowledgements:This work was supported by the Korea Health Technology R&D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health and Welfare, Republic of Korea (grant no.HI14C1277).Disclosure of Interests:None declared

Administration of dextran sulfate sodium (DSS) in drinking water led to significant bout of colitis simulating ulcerative colitis of human. However, colitis usually developed 5 - 7 days after DSS administration. Therefore, we hypothesized host defense system might protect colitis up to 5 days of DSS administration. 2.5% DSS-induced colitis were administered to C57BL/6 mice and sequential measurements of pathology, cyclooxygenase-2 (COX-2), nuclear factor-κB (NF-κB), heme oxygenase-1 (HO-1), NADPH quinone oxidoreductase-1 (NQO1), γ-glutamylcysteine synthetase (γ-GCS), nuclear factor erythroid 2-related factor-2 (Nrf2), and keap1 were done at 2, 6, 12, 24, 48, 96, 120, and 168 hour of DSS administration, respectively. DSS-induced colitis was repeated in either COX-2

Background Both hyperuricemia and hyperhomocysteinemia are known to be associated with the deterioration of vascular endothelial function and are regarded as important risk factors for atherosclerotic vascular diseases. However, there has been no report about the relationship between homocysteine (Hcy) and atherosclerosis in patients with hyperuricemia. Objectives In this study, we evaluated the relationship between the carotid IMT and various clinical parameters including renal function and serum Hcy level in patients with hyperuricemia, and investigated the possible mechanism of how hyperuricemia is related with the increase of carotid IMT. Methods A total of 1228 subjects who visited the health promotion centre of hospital were enrolled in this study. All subjects completed both carotid ultrasonography and laboratory measurement, including serum Hcy levels and renal function. Serum Hcy levels were measured by a competitive immunoassay using direct chemiluminescent. Carotid IMT was evaluated by B-mode carotid ultrasonography. Results Hyperuricemic patients showed higher carotid IMT values compared with normouricemic patients (1.12±0.64 mm vs. 1.02±0.50 mm, p=0.043). The serum Hcy levels were significantly higher in the hyperuricemic group than in the normouricemic group (13.39±4.42 μmol/L vs. 11.69±3.65 μmol/L, p Conclusions Carotid IMT was higher in patients with hyperuricemia than in normouricemic individuals. This study suggests that impairment of the renal function in patients with hyperuricemia may induce the increase in carotid IMT via increased serum Hcy levels. Disclosure of Interest None declared

Background Gout is one of a heterogeneous group of diseases related to hyperuricemia. The measurement of 24 hour urinary uric acid excretion is frequently used to evaluate disease status and select drugs that lower uric acid level. However, 24 hour urine collection is inconvenient and frequently unreliable, due to errors in collection. Therefore, a simpler alternative to the 24 hour urine collection is needed. Objectives We investigated the utility of the random urine uric acid-to-creatinine (UA/CR) ratio in predicting 24 hour urine uric acid excretion in patients with gout. Methods Ninety patients with gout without any use of uric acid lowering agents were enrolled in this study. The mean age was 50.0±16.7 years old and the male patient was 90.0% (81/90) of all participants. For the evaluation of uric acid excretion and renal function, patients were collected 24 hour urine. Random urine uric acid and creatinine specimens were gained on the same day of 24 hour urine collection. Chronic kidney disease was defined as a creatinine clearance (CCr) level of less than 60 ml/min/1.73m2 measured in 24 hour urine collection sample. Excretion of more than 600 mg of uric acid in the 24 hour urine sample was defined as uric acid over-excretion. Results Mean serum uric acid level was 7.73±1.89 mg/dl, and the mean 24 hour uric acid excretion was 666.5±236.2 mg. The random urinary UA/CR ratio showed positive correlation with 24 hour urine uric acid excretion (γ=0.398, p Conclusions The random urine UA/CR ratio correlated with 24 hour urine uric acid excretions in patients with gout. The best cut-off random urine UA/CR ratio value to discriminate uric acid over-excretion was 0.342, with a sensitivity of 74.1% and a specificity of 66.7%. The random urine UA/CR ratio would be a useful predictor to detect patients with urinary uric acid underexcretion, who could then be treated with uricosuric drugs. Disclosure of Interest None declared

Repeated bouts of ulcerative colitis featured troublesome course of inflammatory bowel disease leading to fatal colitis-associated cancer, which is strongly associated with oxidative stress and sustained inflammation. Since oligonol, low molecular weighted polyphenol extracted from fruit lychee, showed antioxidative and anti-inflammatory actions, we hypothesized that oligonolcan prevent relapse of colitis. We compared oligonol with current gold standard therapeutics, sulfasalazine in preventive efficacy of relapse. First, dextran sulfate sodium (DSS)-induced colitis were made following pretreatment with oligonol, 10, 50, and 100 mg/kg for 7 days to measure therapeutic effect of oligonol and relapse model via repeated DSS administration was made following with either 50 mg/kg oligonol or 30 mg/kg sulfasalazine to explore relapse preventing action of oligonol in C57BL/6 mice. Detailed changes in colon were measured to explain molecular mechanisms. Pretreatment of 10, 50, 100 mg/kg oligonol (p.o.), significantly reduced DSS-induced colitis; total pathologic scores, colon length, and clinical symptom scores (P0.05). Oligonol pretreatment significantly decreased the levels of interleukin (IL)-1, IL-6, and tumor necrosis factor-α (TNF-α) as well as nuclear factor-κB (NF-κB), c-Fos, and c-Jun in affected colon tissues, but the expression of heme oxygenase-1 (HO-1) and NADH: quinone oxidoreductase-1(NQO-1) as well as total antioxidant concentration (P0.005) was significantly increased with oligonol. A relapse model established with repeated DSS administration led to high mortality. However, oligonol significantly ameliorated exacerbations of colitis, while sulfasalazine did not (P0.01). Significantly decreased expressions of cyclooxygenase-2 (COX-2), TNF-α, and macrophages inhibition were relapse preventing actions of oligonal, but significant action of oligonol relevant to relapse prevention was either significantly increased expressions of NQO-1 or significantly preserved mucin (P0.05). Concerted anti-inflammatory, antioxidative, and host defense enhancing actions of oligonol can be applied during maintenance therapy of IBD to prevent relapse of IBD.

Although human-sized bipedal humanoid robots have been developed as the ideal form of human-friendly robots, studies of humanoid robots from the user perspective and of actual interaction between humanoid robots and the public in daily environments are few. This paper presents a long-term public demonstration that encouraged interaction between a humanoid robot and unspecified individuals. We have collected a significant amount of subjective evaluation data from the public by performing a storytelling demonstration that enhanced people's empathy towards the robot. The evaluation model consists of the robot's human friendliness, which involves its impression on humans, interaction with humans, and imitation of human motions and the robot's human appearance which involves gender, age, height, and body type. This study shows that there is no significant difference in human-friendliness between gender groups (male and female), while there is a significant difference between age groups (children and adults). In human appearance, it appears that there is no significant difference between either gender groups or age groups, except for the case of the robot's height.

To investigate whether serum leucine-rich α2-glycoprotein (LRG) levels are elevated in patients with adult-onset Still's disease (AOSD) and determine their correlation with disease activity parameters.We enrolled 39 patients with AOSD, 47 patients with rheumatoid arthritis (RA), and 39 controls. Forty-five serum samples from the patients with AOSD were assayed for LRG using an enzyme-linked immunosorbent assay (ELISA). Comprehensive AOSD activity was determined by a modified Pouchot score.Serum LRG levels were significantly elevated in patients with AOSD (128.8±40.8 ng/mL) compared to those in patients with RA and in controls (33.9±15.2 ng/mL, p0.001 and 22.4±6.1 ng/mL, p0.001, respectively). Patients with active AOSD had significantly higher LRG levels than those with inactive disease (141.4±31.3 ng/mL vs. 79.8±37.1 ng/mL, p=0.002). Serum LRG levels were positively correlated with C-reactive protein (CRP; γ=0.387, p=0.015), lactate dehydrogenase (LDH; γ=0.370, p=0.026), ferritin (γ=0.687, p0.001) levels, and the modified Pouchot score (γ=0.756, p0.001). Serum LRG levels decreased significantly after treatment in all six patients with active AOSD who had follow-up evaluations (p=0.007). The best cut-off value for LRG to distinguish AOSD from RA was 67.9 ng/mL, with a sensitivity of 92.3% and a specificity of 97.9%.Serum LRG levels were increased in patients with AOSD and correlated well with disease activity measures. LRG may be a useful biomarker for distinguishing AOSD from RA and for monitoring the disease activity of AOSD.

Recent products of piperacillin/tazobactam (PTZ) from the original manufacturer, previously considered a major cause of galactomannan (GM) false-positivity, are reported not to be related to it. However, data regarding generic PTZ are limited and controversial. To evaluate the effect of generic PTZ on GM false-positivity in Korea, we performed a case-control study in adult patients with cancer. A case-control study was designed. Electronic medical records of cancer patients who were admitted and tested for serum GM between March and June 2014 at a tertiary care university hospital were reviewed. During the study period, a single generic PTZ (C manufacturer, Korea) was used. Patients who received PTZ within 24 h prior to serum GM testing were enrolled. Age- and GM test date-matched non-PTZ patients were selected as controls. A total of 110 patients received PTZ within 24 h prior to serum GM testing during the study period. The GM optical density index (ODI) of the PTZ group did not vary significantly from that of the control group (p = 0.251). The percentage of false-positive patients in the PTZ group was also similar to that of the control group (p = 0.538). There was no statistical relationship between GM ODI titer and time interval from PTZ administration (p = 0.095) or cumulative PTZ dose (p = 0.416). In a case-control study that evaluated 220 patients, a generic PTZ in Korea was not related to GM false-positivity.

군용 차량의 경우 일반적인 도로뿐만 아니라 야지를 주행하게 된다. 야지를 주행 하는 경우가 잦은 군용 차량의 경우 야지 주행에 대한 성능 시험 및 내구 시험이 중요한데, 내구 주행 시험은 비용과 시간으로 인해 제약을 받으므로, 시뮬레이션을 통해 차량의 성능을 분석할 수 있다면 비용과 시간을 줄일 (수 있다.1) 가상주행시험을 통해 차량의 성능을 분석하기 위해서는 신뢰성 있는 차량의 동역학 모델 확보와 시험로에 대한 측정 및 시뮬레이션에 활용할 수 있는 가상 노면이 필요하다. 군용차량의 동역학 모델 개발을 위해 상용 동역학 해석 프로그램인 MSC.ADAMS 를 이용하여 군용 차량의 동역학 모델을 개발하였다. 타이어와 비선형 댐퍼 등에 대하여 부품특성 시험을 통해 타이어의 강성을 계측하여 FTire 모델을 개발하였으며, 도면의 물성 정보와 기하학적 형상을 반영하여 겹판 스프링 모델은 ‘Leaf spring Editor’를 이용하여 개발하였다. 또한, 모델링에 필요한 정보는 휠 하중 계측 등의 실차 시험을 통해 질량정보를 Key Words: Vehicle Model(차량 모델), Bump Test(범프 시험), ADAMS(아담스), Leaf Spring(겹판 스프링) 초록: 군용 차량의 경우 야지 주행에 대한 성능 시험이 필수적인데 실차 시험의 경우 비용과 시간에 의한 제약을 받게 되므로, 시뮬레이션을 통한 성능 분석이 효율적이다. 본 연구에서는 상용 다물체 해석 프로그램인 MSC.ADAMS 를 이용하여 차량 모델을 개발한다. 타이어 수직 강성 시험을 수행하고 FTire 모델에 반영하여 타이어 모델을 생성한다. 댐퍼의 경우 비선형 특성 시험을 통해 얻은 결과를 반영하여 댐퍼를 모델링 하였으며, 겹판 스프링은 빔 요소 모델로 차량 모델을 구성한다. 단순 장애물 통과 시험 및 파형로 통과 시험을 수행하고 가속도 응답 및 휠 하중 응답 분석을 통해 차량 모델의 신뢰성을 검증하였다. Abstract: It is essential to perform driving performance tests of military vehicles on rough terrain. A full car test is limited by cost and time constraints, because of which a dynamic analysis via computer simulation is preferred. In this study, a vehicle model is developed using MSC.ADAMS, a commercial multibody analysis program, and compared via experiments . FTire is modeled using the results of a tire performance test to obtain the vertical stiffness. A nonlinear damper is modeled by a characteristic experiment. Leaf springs are modeled with beam force elements and consisted to a vehicle model . The vertical force and acceleration response of the wheel are identified when vehicle is passing over a simple bump as well as a sinusoidal road. The developed vehicle model is verified with the results of a full car test.

The unavailability of sufficient data at higher elevations causes many uncertainties in research on cold regions. This study considers a cryosphere-hydrology observation system established in 2008 at the Hulu small alpine watershed in the Qilian Mountains of Northwest China. The altitudinal gradient of weather factors is analyzed using data from the Hulu watershed and routine stations located in the Heihe upstream. The data presented here provide the following knowledge of mountain meteorology at elevations from 3367 m to 4166 m/4248 m in the Qilian Mountains: (1) the yearly precipitation—altitude relationship is linear in regions below 4248 m in the Heihe upstream, where the precipitation gradient increased marginally from 1960 to 2011; (2) the yearly air temperature lapse rate (TLR) is weaker at higher elevations (>3000 m), and the seasonal TLR became more divergent between winter and summer half-years from 1960 to 2011 (yearly mean 5.6 °C km-1); (3) in the Hulu watershed, the LRs of water vapo...

This paper presents the experimental torque disturbance analysis of a missile hatch system by spline backlash. The missile hatch system uses a spline and gear train for vertical elevation of the heavy hatch. The spline used for the rotation shaft of the hatch is generally used for automotive driving parts that transmit high amounts of power. It has an angular backlash, which results in jerks. Backlash of the hatch spline influences hatch swinging. The spline backlash and hatch swing are experimentally analyzed by measuring the hatch's rotation angle and acceleration. Hatch swing is visually observable for a short period, and it is measured by measuring the rotation angle variation and hatch acceleration. The shape of fluctuation and duration time of hatch angle variation are similar to those of torque. This shows that the hatch swing due to spline backlash generates torque disturbances. Corresponding Author, eskang@cnu.ac.kr 2014 The Korean Society of Mechanical Engineers C

본 연구의 목적은 실감나는 운전 환경을 제공하는 공기압 구동식 드라이빙 시뮬레이터 개발에 있다. 드라이빙 시뮬레이터의 모션 플랫폼은 운전자에게 실제 차량의 사실적인 느낌을 주는 메카트로닉스 장비이다. 모션 플랫폼의 비용은 드라이빙 시뮬레이터를 개발하는데 가장 큰 부분을 차지한다. 저비용으로 모션 플랫폼을 개발하기 위하여 6개의 공압 실린더로 구성된 스튜어트 플랫폼 형태를 기반으로 모션 플랫폼을 자체 제작하였다. 스튜어트 플랫폼은 조이스틱의 작동신호에 대한 응답으로 만족할 만한 추종성능을 보여주었다. 상용의 레이싱 게임 소프트웨어 중의 하나인 rFactor를 이용하여 드라이빙 시뮬레이터의 가능성을 확인하였다. 【A pneumatically-driven driving simulator that provides a realistic representation of the driving environment was developed. The motion platform for the driving simulator is a mechatronic device that gives a driver the realistic feeling of an actual vehicle. The cost of the motion platform comprises the largest part of the expenses in developing a driving simulator. In this project, to develop a low-cost motion platform, the self-built motion platform based on the Stewart platform configuration that is constructed by six pneumatic cylinders was used as its actuator. The Stewart platform that moves in response to the operating signals of the joystick showed satisfactory tracking performance. We confirmed the possibility of the driving simulator using rFactor that is a commercially available racing game software.】

In this paper, the disturbance applied to launcher hatch by ship motions is introduced to identify the vertical ship motion disturbance. Basically, ship motions are comprised of 6 degrees of freedom: roll, pitch, yaw, heave, surge and sway. In the case of the shipboard launcher hatch the coupled pitch, heave and roll are significant motions to be transformed to a vertical direction motion. The maximum acceleration values are obtained from the vertical motion model and the ship motion data in accordance with ship type and hatch location on the ship. We verify that the maximum pitch motion mainly influences the launcher hatch and also present the quantity of the maximum load disturbance by the ship’s motion acceleration. Keywords: ship motion, 6-DOF, vertical motion model, load disturbance, launcher hatch I. 서론 함정에 탑재되는 일반적인 전기기계 구동장치 및 제어기로 구성되는 함정 시스템은 함정운용 특성에 따른 다양한 외란(disturbance)을 받게 되며 함운용 외란을 제거하기 위한 제어기 설계가 요구된다. 함정 시스템 설계에 필요한 함운용 외란을 실제적으로 측정하여 제어기에 전달하는 경우 시스템 설계가 복잡해지고 고가의 비용이 든다. 따라서 함운용 외란을 잘 분석하여 함정 시스템 설계에 적용한다면 시스템 설계 및 성능 평가에도 유리하고, 설계 및 제작 비용도 절감할 수 있다. 함정에 탑재되는 제어시스템에 작용하는 외란 요소들은 함정종류(ship type) 및 해면상태(sea state)에 의해 결정되는 함정운동(ship motion), 함정의 운항속도(ship speed), 해상에서 부는 바람속도(wind velocity), 적설부하/결빙(icing) 및 함정의 엔진으로부터 전달되는 함진동(ship vibration) 등으로 다양한 형태를 갖는다. 이와 같은 외란 요소들은 함정에 설치되는 안정화 장치(stabilizer) 설계, 유도탄 발사 시의 유도탄 초기 안정성 해석 및 함정 발사대 해치시스템 설계 등에 고려되어야 하는 중요한 설계 요소이다. 특히 함운용시 필수적으로 함정 시스템에 직접 영향을 주는 외란은 함정운동으로 회전운동인 롤(roll), 피치(pitch), 요(yaw) 운동과 병진운동인 히브(heave), 서지(surge), 스웨이(sway) 운동으로 6자유도 운동으로 구성된다. 함정 시스템 설계를 위하여 이러한 함정운동 외란에 대한 식별(identification), 해석(analysis), 추정(estimation) 및 예측(prediction)에 관한 연구가 많이 수행되고 있다. 함정운동과 관련한 주요 연구들로 함정 형상 설계, 함정 운항제어, 함정운동에 대한 보상 및 제어응용을 위한 수학적 모델링 및 시뮬레이션 기법 등이 많이 연구되어 왔다[1,2,10, 11]. 함정운동은 실제 측정한 데이터를 분석하여 예측이 가능하지만 여러 운동이 중첩되어 있어 신경망(neural) 네트워크를 사용하여 조합(couple)된 함정운동에 관한 연구도 수행되었다[3]. 또한 함정에서 유도탄을 발사하기 위해서는 함정운동 외란을 고려한 유도탄 발사 초기 거동에 대한 안정성 해석이 중요하므로 함정운동 외란을 확률변수로 적용하여 유도탄 발사 안정성에 관한 연구도 수행되었다[4]. 함정 갑판에 항공기 착륙을 위하여 칼만 필터를 사용하여 실시간 함정운동을 추정하였으며[5], 또한 ISAR (Inverse Synthetic Aperture Radar) 데이터를 측정하여 함정운동을 추정하는 기법을 제시하였다[6]. 본 논문에서는 함정의 COG (Center of Gravity) 또는 COF (Center of Floating)에 작용하는 함정운동 데이터를 사용하여 함정에 탑재되는 발사대 해치에 작용하는 함정운동 외란에 대해서 분석하고, 함정운동 가속도에 의해 발생되는 부하 외란의 크기를 제시하여 해치시스템 설계 및 제어기 설계에 활용할 수 있도록 한다. II. 함정운동 분석 1. 좌표시스템 및 기본개념 그림 1은 함정운동을 나타내기 위한 좌표시스템으로 함정 운동의 중심점인 COG 또는 COF 기준의 X, Y, Z 좌표와 함정에 탑재되는 발사대 해치 COG기준의 x, y, z 좌표로 나타내었다. 그림 2는 함정의 COF 기준축을 중심으로 발생되는 함정의 6자유도 운동 방향을 나타낸다. 6자유도 함정운동은 히브, 서지, 스웨이 병진운동과 롤, 피치, 요 회전운동으로 구성된다. 발사대 해치에 전달되는 함정운동은 함정 중심점에서의 함정운동 모델과 함정 중심점에서의 발사대 탑재 위치를 사용하여 계산할 수 있다. 함정운동 모델은 일반적으로 정현모델(sinusoidal model)과 과도모델(transient model)을 사용한다. 정현모델은 함정의 종