Hong-Kyu Kim

Clinical significance of subclinical varicocelectomy in male infertility: systematic review and meta-analysis

Recent meta‐analysis by the Cochrane collaboration concluded that treatment of varicocele may improve an infertile couples chance of pregnancy. However, there has been no consensus on the management of subclinical varicocele. Therefore, we determine the impact of varicocele treatment on semen parameters and pregnancy rate in men with subclinical varicocele. The randomised controlled trials that assessed the presence and/or treatment of subclinical varicocele were included for systematic review and meta‐analysis. Random effect model was used to calculate the weighted mean difference of semen parameters and odds ratio of pregnancy rates. Seven trials with 548 participants, 276 in subclinical varicocelectomy and 272 in no‐treatment or clomiphene citrate subjects, were included. Although there was also no statistically significant difference in pregnancy rate (OR 1.29, 95% CI 0.99–1.67), surgical treatment resulted in statistically significant improvements on forward progressive sperm motility (MD 3.94, 95% CI 1.24–6.65). However, the evidence is not enough to allow final conclusions because the quality of included studies is very low and further research is needed.

Risk of incident Mycobacterium tuberculosis infection in patients with inflammatory bowel disease: a nationwide population‐based study in South Korea

The low incidence of Mycobacterium tuberculosis infection and lack of adequate controls have prevented researchers from estimating tuberculosis (TB) risk in inflammatory bowel disease (IBD) patients.

Incidence, Prevalence, Mortality and Causes of Death in Systemic Sclerosis in Korea: A Nationwide Population-Based Study.

DEAR EDITOR, While the epidemiology of systemic sclerosis (SSc) is known to vary by geographical region and race, studies at the national level, as well as reports from Asian countries, are scarce, and the majority of existing studies were limited to cases from small geographical areas. The risk of mortality in patients with SSc has been reported to be higher than in the general population. However, most previous studies were based on referral centres, where patients’ severity may be different from that of the general patient population. Therefore, a large-scale population-based study is needed to produce a reliable estimate. In this study, we investigated the incidence, prevalence, mortality and causes of death of patients with SSc in Korea from 2008 to 2013, using the Korean Rare Intractable Disease (RID) registry database linked with the Health Insurance Review and Assessment Services (HIRA) database, which covers the entire Korean population (50 million). To be registered in the RID registry as a patient with SSc, the diagnosis should be made by a physician based on uniform criteria predefined by the government, which are identical to the American College of Rheumatology (ACR) criteria. Also, the diagnosis is reviewed by another healthcare professional in the institution before its final submission to the government. Through this process, we believe the diagnosis is reliable. We defined an incident case as a newly diagnosed and registered patient in the RID registry in that year, with a 2-year washout period. Prevalent cases were defined as all patients with SSc registered in the HIRA-RID database in the corresponding year. Cause of death and vital status of patients with SSc were determined by linking the HIRA-RID database with Statistics Korea, which contains information on the causes of death of all deceased Koreans diagnosed by a physician according to

Effect of Bonding Condition on the Tensile Properties of Diffusion Bonded Haynes230

This study investigated the effect of bonding temperature and holding time on microstructures and mechanical properties of diffusion bonded joint of Haynes230. The diffusion bonds were performed at the temperature of 950, 1050, and for holding times of 30, 60, 120 and 240 minutes at a pressure of 4MPa under high vacuum condition. The amount of non-bonded area and void observed in the bonded interface decreased with increasing bonding temperature and holding time. Cr-rich precipitates at the linear interface region restrained grain migration at and . However, the grain migration was observed in spite of short holding time due to the dissolution of precipitates to base metal in the interface region at . Three types of the fracture surface were observed after tensile test. The region where the coalesce and migration of grain occurred much showed high fracture load because of base metal fracture whereas the region where those did less due to the precipitates demonstrated low fracture load because of interface fracture. The expected fracture load could be derived with the value of fracture area of base metal () and interface (),

Thermal Analysis of Nickel-Base Superalloys by Differential Scanning Calorimetry

Load

Analyses of Creep Properties of Ni-base Superalloy Powders as Cooling Rate after Solid Solution Heat Treatment

Appropriate thermo-mechanical properties of nickel-based superalloys are achieved by heat treatment, which induces precipitation and solid solution hardening; thus, information on the temperature ranges of precipitation and dissolution of the precipitates is essential for the determination of the heat treatment condition. In this study, thermal analyses of nickel-based superalloys were performed by differential scanning calorimetry method under conditions of various heating rates of 5, 10, 20, or 40K/min in a temperature range of 298~1573K. Precipitation and dissolution temperatures were determined by measuring peak temperatures, constructing trend lines, and extrapolating those lines to the zero heating rate to find the exact temperature under isothermal condition. Determined temperatures for the precipitation reactions were 813, 952, and 1062K. Determined onset, peak, and offset temperatures of the first dissolution reaction were 1302, 1388, and 1406K, respectively, and those values of the second dissolution reaction were 1405, 1414, and 1462K. Determined solvus temperature was 1462K. The study showed that it was possible to use a simple method to obtain accurate phase transition temperatures under isothermal condition.

THU0514 Seasonal Variations of Episodes of Acute Gouty Arthritis: A Systematic Review and Meta-Analysis

In this study, solid solution heat treatment of consolidated nickel-based superalloy powders is carried out by hot isotactic pressing. The effects of the cooling rate of salt quenching, and air cooling on the microstructures and the mechanical properties of the specimens are analyzed. The specimen that is air cooled shows the formation of serrated grain boundaries due to their obstruction by the carbide particles. Moreover, the specimen that is salt quenched shows higher strength than the one that is air cooled due to the presence of fine and close-packed tertiary gamma prime phase. The tensile elongation at high temperatures improves due to the presence of grain boundary serrations in the specimen that is air cooled. On the contrary, the specimen that is salt quenched and consists of unserrated grain boundaries shows better creep properties than the air cooled specimen with the serrated grain boundaries, due to the negative creep phenomenon.

Technological Review on the Development of Metallic Armor Materials

Background Acute gouty arthritis is the inflammatory arthritis with abrupt and intermittent nature of attack. Objectives The aim of this study was to analyze the seasonal variations of episodes of acute gouty arthritis. Methods We searched MEDLINE, EMBASE, the Cochrane library, and KoreaMed for all articles published before November 2015. Studies with quantitative data on episodes of acute gouty arthritis by months and/or seasons were included. Meta-analysis for episodes of acute gouty arthritis was done by seasons and months. Subgroup analyses by the confirmatory methods of acute gouty arthritis were done by seasons. Results Ten studies published between 1920 and 2015 were included, containing a total of 29,863 subjects. Plotting of episodes of acute gouty arthritis by months showed higher episodes during the period from March to July than other months. The risk ratio of episodes of acute gouty arthritis in spring was 1.21 (95% CI: 0.95 to 1.55, I2=86%; p=0.12), 1.32 (95% CI: 0.98 to 1.78, I2=90%; p=0.07), 1.27 (95% CI: 1.02 to 1.59, I2=81%; p=0.03) when compared to summer, fall and winter, respectively. Therefore, spring had significantly higher episodes of acute gouty arthritis than winter. Subgroup analyses by confirmatory methods of episodes of acute gouty arthritis were as follows: 1) The risk ratio of acute gouty arthritis confirmed by the presence of monosodium urate in synovial fluid in spring was 1.46 (95% CI: 1.22 to 1.76, I2=0%; p<0.0001), 1.28 (95% CI: 1.07 to 1.54, I2=7%; p=0.007), 1.24 (95% CI: 0.93 to 1.65, I2=59%; p=0.15) when compared to summer, fall and winter, showing that spring had significantly higher episodes of acute gouty arthritis than summer and fall; 2) The risk ratio of acute gouty arthritis confirmed by the presence of inflammation in synovial fluid was 1.53 (95% CI: 1.31 to 1.80, I2=0%; p<0.00001), 1.44 (95% CI: 1.07 to 1.93, I2=69%; p=0.02), 1.28 (95% CI: 1.05 to 1.55, I2=40%; p=0.01) when compared to summer, fall and winter, showing that spring had significantly higher episodes of acute gouty arthritis than 3 other seasons. Conclusions This seems to be the first systematic review and meta-analysis on seasonal variations of acute gouty arthritis. Based on our study, the acute gouty arthritis might be developed more frequently during the period from spring. Increase in physical activity, dehydration, and seasonal variation of cortisol level could be related with this seasonal variation of episodes of acute gouty arthritis. References Choi HJ, Lee CH, Lee JH, Yoon BY, Kim HA, Suh CH, Choi ST, Song JS, Joo H, Choi SJ, Lee JS, Shin K, Jun JB, Baek HJ. Seasonality of gout in Korea: a multicenter study. J Korean Med Sci. 2015 Mar;30(3):240–4. Elliot AJ, Cross KW, Fleming DM. Seasonality and trends in the incidence and prevalence of gout in England and Wales 1994–2007. Ann Rheum Dis. 2009 Nov;68(11):1728–33 Disclosure of Interest None declared

Outline of Explosion Bulge Test in Air of Welding Structure

This paper describes the state of the art for the development of metallic armor materials which are mainly used as armor plates of the combat vehicles. Several important micro-structural features affecting ballistic properties of the metallic armor are discussed. Optimization of the strength and toughness balance of the metallic armor is necessary for the improvement of the ballistic performance resulting from maximizing the resistance to the penetration of the bullet and also to brittle failure of the plates. Understanding and control of the adiabatic shearing phenomenon developed remarkably during high strain rate deformation is needed to prevent brittle failure of the metallic armor materials.

An intermediate temperature creep model for Ni-based superalloys

1998년 국내에서 처음으로 1,200톤급 잠수함이 건 조된 이래 11척의 1,200톤급 잠수함이 건조되었으며, 1,800톤급 잠수함도 3척이 건조되어 운용되고 있다. 2003년도부터는 4,500톤급 구축함이 진수되어 2004 년도에 실전 배치되었으며, 7,600톤급 구축함 3척이 운용될 예정이고, 4,500톤급과 7,600톤급의 중간 크 기의 구축함인 KDX IIA 가 2019년부터 전력화 예정 인 것으로 알려져 있다. 우리나라 주변국인 일본, 중국, 러시아 등은 우리나 라가 보유한 잠수함 및 구축함보다 성능과 규모 면에서 뛰어난 체계를 갖추기 위해 투자를 대폭 늘이고 있으며 해군력의 증강에 총력을 기울이고 있다. 국내에서도 이 러한 추세를 감안하여 해군력의 증강에 장기적으로 많 은 예산을 투자하고 있는 것으로 판단된다. 잠수함 및 구축함의 건조시 초기에는 외국의 설계와 기술이 도입되었지만 현재는 국내의 독자 설계 및 축척 된 기술로 건조가 가능하다. 잠수함 및 구축함은 구조적으로 압력을 받는 용접구 조물로서 해저 및 해상에서 부위에 따라 많은 압력을 받으며, 또한 기뢰나 폭뢰, 어뢰 등의 공격을 받을 수 있기 때문에 구조물의 안정성 확보가 중요한 문제로 인 식되고 있으며, 독일 및 미국에서는 용접부에 대해 부 풀음 시험을 하도록 규격으로 정하고 있다. 미국에서는 T0974-BD-GIB-101/300에 의해 폭파변형시험을 실 시하며 공기중에서 시험온도에 따른 초기 균열발생 및 균열전파에 의해 저항성을 평가하는 방법이 있으며 이 방법에 대해 소개한 바 있다. 미국에서는 공기중에서 폭파시험을 수행하지만 독일에서는 수중에서 폭파시험 을 수행하고 있으며 Nato Stang 4137에 실험방법을 규정해 놓았다. 국내에서 건조된 209함중 6번함까지는 수입된 고강도 판재인 HY-80강이 사용되었으나, 209 함 7번함부터 214함은 모두 국내에서 개발된 DS80 강 및 DS-100강이 각각 적용되었다. 이 들 잠수함 건 조는 알려진 바와 같이 모두 독일로부터 기술 도입에 의해 건조되었으며, 국내 개발된 모재 및 용접 판재에 대해 독일에서 수중 폭파시험을 수행하여 인증을 득한 후 잠수함에 적용될 수 있었다. 추후 국내 기술에 의해 잠수함, 수상함 건조를 위해서는 폭파변형시험의 국내 인증이 필요할 것이다. 공기중 폭파변형시험 방법 및 절차는 규격에 자세히 명기 되어 있지만, 수중폭파시험 과 관련된 규격 및 방법은 비밀로 분류되어 있어 이에 대한 국내 개발이 필요하였다. 국방과학연구소에서는 독일에서 평가된 시험편의 수 중폭파시험 결과를 분석하여 국내에서 가능한 수중폭파 시험 기술을 확보하여 국내에서 생산된 강재에 대해 수 중 폭파시험을 수행하여 선각재용 강재 및 용접부의 사 용 적합성을 평가하였다. 본 고에서는 국내에서 개발된 수중폭파시험 기법에 대해 간략히 기술하고자 한다.