• Korean Journal of Veterinary Research
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• v.50 no.1
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• pp.55-57
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• 2010

Torque teno virus (TTV), a species of Anellovirus, is a non-enveloped single stranded DNA virus with a wide range of animal hosts. The incidence of TTV is quite ubiquitous throughout the world. A total of 235 serum samples obtained from 137 pigs and 98 cattle at slaughterhouses in Korea during April 2005 to May 2005 were tested by TTV-specific PCR as to monitor prevalence of TTV among swine and cattle. As a result, the prevalent rates of TTVs in pigs and cattle were 43.1% and 4.1%, respectively. It seems that TTV infection is quite prevalent in swine population.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.8 no.2
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• pp.202-212
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• 2005

Purpose: Transfusion transmitted virus (TTV) is a newly discovered virus and to date the contribution of TTV to liver disease remains unclear. Little is known about the frequency of TTV infection in children in Korea. The purpose of this study was to investigate the prevalence and genotypic distribution of TTV carried by healthy children and patients with hepatitis in Korea. Methods: Eighty eight of healthy children and three groups of patients with hepatitis-14 patients with chronic hepatitis B, 12 patients with chronic hepatitis C and 25 patients with hepatitis of unknown etiology-were tested. TTV DNA was detected by semi-nested PCR using primer sets generated from N-22 region and from 5' noncoding region (NCR) of the viral genome. PCR products derived from 8 patients with hepatitis and from 11 healthy children were sequenced and a phylogenetic tree was constructed. Results: TTV was found by PCR with N22 primer in 11.3% of healthy children, 28.5% of children with hepatitis B, 25% of children with hepatitis C, 24% of children with hepatitis of unknown etiology. TTV DNA was found by PCR with 5'NCR primer in 32.9% of healthy children, 71.4% of patients with chronic hepatitis B, in 50% of patients with hepatitis C and in 48% of patients with hepatitis of unknown etiology. TLMV DNA was found in 48.9% of healthy children, 21.4% of patients with hepatitis B, 16.6% of patients with hepatitis C, 40% of patients with hepatitis of unknown etiology. Among the sequenced isolates, 10(52%) belonged to genotype 1 (G1) and others belonged to genotype 2 (G2) or genotype 3 (G3). Among the G1 sequences, 7 were grouped as G1a. Conclusion: TTV infection was common in healthy children and in patients with hepatitis. But, the prevalence of TTV DNA by 5'NCR primer was relatively high in patients with hepatitis B and there may be some association between TTV and hepatitis B virus infection. G1 was the major genotype of the studied population.

• Pediatric Infection and Vaccine
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• v.11 no.2
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• pp.153-157
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• 2004

Purpose : Ttransfusion transmitted virus(TTV) is a circular DNA and consists of diverse genotypes and variants. The pathogenecity of TTV is still unclear. Recently another circular single stranded DNA virus, distantly related to TTV was isolated from the sera of blood donors, designated as Transfusion transmitted virus like minivirus(TLMV). TTV and TLMV show greater sequence divergence from each other than between genotypes of TTV. We planned to know the prevalence of TLMV in children. Methods : TLMV DNA was detected by PCR primers from noncoding region of the genome in 88 children without hepatitis, aged 0~15 years. PCR products derived from 10 children were directly sequenced and phylogenetic analysis was undertaken. Results : TLMV DNA was detected in 49% of 88 children without hepatitis. The prevalence of TLMV varied with age : <1 y, 16%(4/25); 1~3 y, 62%(18/29); 4~6 y, 43%(7/16); 7~9 y. 16%(1/6); 10~15 y, 66%(8/12). Mixed infection with TTV was confirmed in 22% of 88 children. Pyhlogenetic analysis of 10 TLMV sequences showed much heterogeneity compared to sequences of GenBank. Conclusion : TLMV prevalence in children was 49% in Korean children. Our TLMV sequence did not cluster in any sequence of TLMV in the GenBank.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.88-93
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• 2023

As the demand for High Bandwidth Memory (HBM) increases and the handling capability of larger wafers expands, ensuring reliable Total Thickness Variation (TTV) measurement for stacked wafers becomes essential. This study presents the design of a measurement module capable of measuring TTV across the entire area of a 300mm wafer, along with estimating potential mechanical measurement errors. The module enables full-area measurement by utilizing a center chuck and lift pin for wafer support. Modal analysis verifies the structural stability of the module, confirming that both the driving and measuring parts were designed with stiffness exceeding 100 Hz. The mechanical measurement error of the designed module was estimated, resulting in a predicted measurement error of 1.34 nm when measuring the thickness of a bonding wafer with a thickness of 1,500 ㎛.

• Journal of Veterinary Science
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• v.22 no.4
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• pp.52.1-52.8
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• 2021

Background: The normal vertebral anatomy of Korean raccoon dogs and their variants require research attention as a prerequisite for identifying pathologies and anomalies. Objectives: This retrospective study aimed at describing the vertebral formula and congenital vertebral anomalies in Korean raccoon dogs (Nyctereutes procyonoides koreensis). Methods: Radiographs of 82 raccoon dogs (42 males, 40 females) acquired from May 2013 to June 2020 in the Gangwon Wildlife Medical Rescue Center were reviewed to evaluate the cervical, thoracic, and lumbar vertebrae of the spine. Results: Normal morphology of all vertebrae was observed in 50 of the 82 raccoon dogs, and the vertebral formula was cervical 7, thoracic 13, and lumbar 7. Congenital vertebral anomalies were found in 32 raccoon dogs: transitional vertebrae (TV) in 31 and block vertebrae in 2. Two raccoon dogs had 2 types of vertebral anomalies: one had TV and block vertebra, and the other had 2 types of TV. Twenty-nine raccoon dogs had thoracolumbar TV (TTV) and 3 had lumbosacral TV. TTV was morphologically classified into 4 different types: unilateral extra-rib in 5 raccoon dogs, bilateral extra-ribs in 14, bilateral elongated transverse processes in 4, and an asymmetric mixed formation of extra-rib with elongated transverse process in 6. Conclusions: This study showed that TTV is common in Korean raccoon dogs, and that the vertebral formula is relatively diverse. The bilateral extra-ribs type TTV is the most common variant, which is almost similar to normal rib to be confused the radiographic evaluation.

• Journal of the Semiconductor & Display Technology
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• v.22 no.3
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• pp.8-13
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• 2023

High bandwidth memory a core technology of the future memory semiconductor industry, is attracting attention. Temporary bonding and debonding process technology, which plays an important role in high bandwidth memory process technology, is also being studied. In this process, total thickness variation is a major factor determining wafer performance. In this study, the reliability of the equipment measuring total thickness variation is identified, and the servo motor settling, and wafer total thickness variation measurement accuracy are analyzed. As for the experimental variables, vacuum, acceleration time, and speed are changed to find the most efficient value by comparing the stabilization time. The smaller the vacuum and the larger the radius, the longer the settling time. If the radius is small, high-speed rotation performance is good, and if the radius is large, low-speed rotation performance is good. In the future, we plan to conduct an experiment to measure the entire of the wafer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1-5
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• 2005

The grinding process is replacing lapping and etching process because significant cost savings and performance improvemnets is possible. This paper presents the experimental results of wafer grinding. A three-variable two-level full factorial design was employed to reveal the main effects as well as the interaction effects of three process parameters such as wheel rotational speed, chuck table rotational speed and feed rate on TTV and STIR of wafers. The chuck table rotaional speed was a significant factor and the interaction effects was significant. The ground wafer shape was affected by surface shape of chuck table.

• Tribology and Lubricants
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• v.32 no.2
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• pp.61-66
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• 2016

Total thickness variation (TTV), BOW, and surface roughness are essential characteristics for high quality sapphire substrates. Many researchers have attempted to increase removal rate by controlling the key process parameters like pressure and velocity owing to the high cost of consumables in sapphire chemical mechanical polishing (CMP). In case of the pressure approach, increased pressure owing to higher deviation of pressure over the wafer leads to significant degradation of the TTV. In this study, the authors focused on reducing TTV under the high-pressure conditions. When the production equipment polishes multiple wafers attached on a carrier, higher loads seem to be concentrated around the leading edge of the head; this occurs because of frictional force generated by the combination of table rotation and the height of the gimbal of the polishing head. We believe the skewed pressure distribution during polishing to be the main reason of within-wafer non-uniformity (WIWNU). The insertion of a hub ring between the polishing head and substrate carrier helped reduce the pressure deviation. Adjusting the location of the hub ring enables tuning of the pressure distribution. The results indicated that the position of the hub ring strongly affected the removal profile, which confirmed that the position of the hub ring changes the pressure distribution. Furthermore, we analyzed the deformation of the head via finite element method (FEM) to verify the pressure non-uniformity over the contact area Based on experiment and FEM results, we determined the optimal position of hub ring for achieving uniform polishing of the substrate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.147-148
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.233-234
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• 2011