Junhyun Cho

Diameter of the normal fetal thymus on ultrasound

To present the normative data of the transverse diameter of the developing fetal thymus.

Angiomyolipoma with minimal fat: differentiation of morphological and enhancement features from renal cell carcinoma at CT imaging.

Background Angiomyolipoma (AML) with minimal fat may mimic renal cell carcinoma (RCC) and is difficult to distinguish from RCC with imaging studies alone. Precise diagnostic strategies have been explored to discern AML with minimal fat from RCC. Purpose To compare the morphological and enhancement features of AML with minimal fat with those of size-matched RCC on computed tomography (CT). Material and Methods Our study included 143 pathologically proved renal tumors (29 AML with minimal fat: mean diameter, 2.5 cm; range, 1.2–4 cm; 114 RCC: mean diameter, 2.8 cm; range, 1.3–4 cm). All patients underwent biphasic helical CTs. Two radiologists retrospectively evaluated the morphological (i.e. non-round and round appearances, with or without capsule) and enhancement features (i.e., wash-out, gradual, or prolonged). For the parameters that had statistically significance between the two groups, we calculated the positive and negative predictive values by using the univariate χ2 test. P < 0.05 indicated a significant difference. Results AML with minimal fat showed a non-round appearance without a capsule (n = 24, 83%) and prolonged enhancement (n = 20, 69%). The positive and negative predictive values of the non-round appearance without capsule for differentiating AML with minimal fat from RCC were 82.8% and 95.6%, respectively. The positive and negative predictive values of prolonged enhancement were 62.5% and 90.8%, respectively. These features were valuable predictors for AML with minimal fat from RCC. Conclusion CT images with non-round shape without capsule and prolonged enhancements may be used to differentiate AML with minimal fat from RCC.

Measurement of compensatory hyperplasia of the contralateral kidney: usefulness for differential diagnosis of fetal unilateral empty renal fossa

To assess the usefulness of sonographic evaluation of compensatory hyperplasia of the contralateral kidney for the differential diagnosis of fetal unilateral empty renal fossa (ERF).

In‐utero development of the fetal anal sphincter

To investigate the in‐utero development of the fetal anal sphincter using transabdominal ultrasound.

Prenatal ultrasound findings of fetal urethral duplication

Urethral duplication is a rare congenital anomaly with approximately 300 cases described in the literature1–13. Most of the reported cases are of incomplete duplications. The anomaly is more common in males2, with few cases reported in females6, and the embryology of the condition is unclear. Most patients are asymptomatic, except for a double stream on micturition. Some patients present with urinary tract infections, incontinence or bladder outflow tract obstruction. Associated genitourinary anomalies and lumbar spine anomalies have been reported3,11,14,15. We could find no cases of prenatally diagnosed urethral duplication described in the literature. We report the prenatal ultrasound and postnatal imaging findings of a case of fetal urethral duplication. A 36-year-old woman underwent a targeted ultrasound examination at 31 weeks’ gestation because of fetal dilatation of the renal pelves and ureters. This revealed bilateral dilatation of the renal pelves and ureters of a male fetus. Periodic changes of the renal pelvic and ureteral diameters suggested vesicoureteral reflux (VUR). The urinary bladder was dilated for > 2 h, suggesting bladder outlet obstruction, but posterior urethral dilatation was not detected. During fetal urination, the urine flow through the urethra was divided into upper and lower flows on color Doppler ultrasound imaging, suggesting urethral duplication (Figure 1). Postnatal examination revealed two urethral orifices and a duplicated urethra. On voiding cystourethrography, the upper urethral opening was normally located but the lower opening was on the ventral surface. Despite its abnormal location, the ventral urethral opening was almost normal in shape. There was a web-like structure on the proximal portion of the ventral urethra, and the lumen to the bladder was not visualized (Figure 2). The patient frequently voided and had a weak double stream. On follow-up ultrasound examination of the kidney 2 months later, hydroureteronephrosis had progressed and a Tc-99m DTPA renal scan revealed delayed excretion in the left kidney. The patient underwent a vesicostomy, Deflux injection (Oceana Therapeutics Ltd., Dublin, Republic of Ireland) and incision to broaden the meatus at the distal end of the ventral surface. Followup voiding cystourethrography 1 year after the operation showed persistent Grade V right VUR and urethral duplication. The left VUR had resolved. The most widely accepted classification system of urethral duplication is that proposed by Effmann et al.1. According to Effmann’s classification, our case was Type IIA2, in which the second channel arises from the first independently and courses into a second meatus. The urethral duplication was initially detected on prenatal ultrasound examination in association with dilatation of the renal pelves and ureters. The hydroureteronephrosis progressed after birth and the patient underwent a vesicostomy. It is not clear whether or not the hydroureteronephrosis resulted from the urethral duplication. The duplication was first identified on color Doppler imaging of fetal voiding. Fetal voiding is usually visible on color Doppler imaging, and our case illustrates the utility of this imaging modality in providing helpful information in cases with anomalies of the lower urinary tract and external genitalia. Patients with urethral duplication are usually asymptomatic, except for a urinary double stream and cosmetic problems. However, depending on the urethral anatomy, the clinical presentation can vary from no symptoms to VUR or renal dysfunction. In our case VUR developed and the excretory function of the left kidney was decreased. Both cosmetic problems and accompanying VUR can be an indication for surgical treatment. Therefore, in the surgical management of urethral duplication, a thorough work-up is needed to detect associated anomalies and to identify the type of duplication. Our case highlights the need to investigate accompanying co-existing conditions, such as VUR, which can result in kidney dysfunction. Radiological evaluation, including voiding cystourethrography, retrograde urethrogram and renal ultrasound, are important to delineate the physiology of the genitourinary system and the anatomy of the urethral duplication and for comprehensive follow-up.

Sonographic findings of uterine sacculation during pregnancy

in either the celomic fluid or the maternal serum in four female fetuses that served as controls. Total cfDNA (βglobin DNA) was consistently found in all samples. The concentration gradient of fetal cfDNA between the amniotic fluid (highest), celomic fluid (lower) and maternal serum (lowest) would seemingly indicate that the fetus itself is the source of fetal cfDNA in the maternal serum. However, it is very unlikely that fetal cfDNA from the early amniotic fluid could reach the maternal circulation because exchange at the level of the yolk sac is mainly unidirectional towards the fetus and the amniotic membrane is practically impermeable to large molecules8. Given that the estimated size of fetal cfDNA in maternal circulation is 100–300 base pairs9, which is equivalent to about 30–90 kDa, and the transfer through the amniotic membrane is negligible for molecules of similar size (e.g. human albumin), it appears that the source of cfDNA in the amniotic fluid is the fetus and the source in the maternal serum is the placenta. The alternative mechanism of direct transfer of fetal cfDNA between the fetal and maternal circulations is also unlikely because the uteroplacental circulation is established only after 10 weeks’ gestation10. In support of this, a recent study found that the concentration of cfDNA in maternal serum was similar in normal and anembryonic pregnancies, indicating that the trophoblast is the source of cfDNA in maternal blood, even in the absence of a fetus or fetoplacental circulation3. The robustness of our results is restricted by the small sample size, which mostly arose from the exclusion of most of the samples of the initial pool (female fetuses, n = 4; male fetuses without amniotic fluid, n = 3). In summary, the SRY and DYS14 markers are detected in the fluid compartments of very early pregnancy. Their distribution in the maternal serum and fetal fluid compartments provides preliminary evidence that the most likely source of fetal cfDNA in the maternal circulation is the trophoblast. A larger sample would be required in order to draw definite conclusions.

Development of the Supercritical Carbon Dioxide Power Cycle Experimental Loop in KIER

Three supercritical carbon dioxide (CO2) power cycle experimental loops have been developed in Korea Institute of Energy Research (KIER) from 2013. As the first step, a 10 kWe-class simple un-recuperated Brayton power cycle experimental loop was designed and manufactured to test its feasibility. A 12.6 kWe hermetic turbine-alternator-compressor (TAC) unit which is composed of a centrifugal compressor, a radial turbine and the gas foil bearings was manufactured. The turbine inlet design temperature and pressure were 180 °C and 130 bar, respectively. Preliminary operation was successful at 30,000 RPM which all states of the cycle existed in the supercritical region. Second, a multi-purpose 1 kW-class test loop which operates as a transcritical cycle at a temperature of 200 °C was developed to concentrate on the characteristics of the cycle, control and stability issues of the cycle. A high-speed turbo-generator was developed which is composed of a radial turbine with a partial admission nozzle and the commercial oil-lubricated angular contact ball bearings. Finally, a 60 kWe-class Brayton cycle is being developed which is composed of two turbines and one compressor to utilize flue-gas waste heat. As the first phase of development, a turbo-generator which is composed of an axial turbine, a mechanical seal and the oil-lubricated tilting-pad bearings was designed and manufactured.Copyright

Study on the Durability Characteristics of the PEM Fuel Cells having Gas Diffusion Layer with Different Micro Porous Layer Penetration Thicknesses

3 JNTG Co., Ltd., 235-36 Mannyun-ro, Jeongnam-myeon, Hwasung-si, Gyeonggi-do 445-961, Republic of Korea Abstract >> Durability characteristics of Gas Diffusion Layer(GDL) is one of the important issues for accomplishing commercialization of Proton Exchange Membrane Fuel Cell(PEMFC). It is strongly related to the performances of PEMFC because one of the main functions of GDL is to work as a path of fuel, air and water. When the GDL does not work on their proposed functions due to the degradation of durability, mass transfer in PEMFC is disturbed and it might cause the flooding phenomenon. Thus, investigating the durability of GDL is important and understanding the GDL degradation process is needed. In this study, electrochemical degradation with carbon corrosion is introduced. The carbon corrosion experiment is carried out with GDLs which have different MPL penetration thicknesses. After the experiment, the amount of degradation of GDL is measured with various properties of GDL such as weight, thickness and performance of the PEMFC. The degraded GDL shows loss of their properties.

P01.19: Prenatal US diagnosis of infantile hepatic hemangioendothelioma: a case report

Results: We identified 84 cases. 24 had associated gastro-intestinal tract and respiratory anomalies; 22 had abnormal karyotypes (10 Trisomy 18s, 5 Trisomy 21s and 1 each of other aneuploidies or other karyotypical abnormalities); 6 had neuromuscular syndromes; 3 had major central nervous system anomalies; 7 had renal anomalies causing anhydramnios; 5 had other genetic syndromes; 2 had placental insufficiency leading to anhydramnios; 8 were found to have normal stomach appearances and had normal outcomes and 7 had a normal outcome despite persistently absent stomach on ultrasound examination. Of these 84: 26 underwent termination of pregnancy; 9 suffered in utero fetal demise; 8 died in the neonatal period; 3 died in infancy; 44 had a live birth and survived infancy and 5 outcomes were not obtained. Conclusions: A persistently absent stomach on ultrasound scanning is associated with a guarded prognosis – with an incidence of abnormal karyotype of 29% and a high incidence of associated structural abnormalities. In only 9.2% of persistently absent stomachs was the outcome normal. We have not been able to explain why these normal fetuses did not demonstrate stomach ‘bubbles’ on ultrasound.

Numerical Analysis of the Gas Flow Distribution Characteristics in the Anode Flow Channel of Molten Carbonate Fuel Cell (MCFC)

조준현 * 하태훈 · * 김한상 · ** 민경덕 · 박종훈 · *** 장인갑 · *** 이태원 · *** Abstract A three-dimensional computational fluid dynamics (CFD) analysis is performed to investigate flow characteristics in the anode channels and manifold of the internal reforming type molten carbonate fuel cell (MCFC). Considering the computational difficulties associated with the size and geometric complexity of the MCFC system, the polyhedral meshes that can reduce mesh connectivity problems at the intersection of the channel and the manifold are adopted and chemical reactions inside the MCFC system are not included. Through this study, the gas flow rate uniformity of the anode channels is mainly analyzed to provide basic insights into improved design parameters for anode flow channel design. Results indicate that the uniformity in flow-rate is in the range of ±1% between the anode channels. Also, the mal-distributed inlet flow-rate conditions and the change in the size of the manifold depth have no significant effect on the flow-rate uniformity of the anode channels.