• Journal of the Korean Society of Tobacco Science
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• v.18 no.1
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• pp.12-20
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• 1996

The spermatogenesis and chromosome number were investigated in the pupal testes of Helicouerpa assulta Guenee by light microscopy. During the spermatogenesis, each bundle of P8(256) sperms developed by 6 mitotic and 2 meiotic spermatogonial divisions. From the early stage of spermatogenesis, it was distinguishable between two kinds of sperm differentiation, eupyrene and apyrene spermatogenesis, which are characteristic in Lepidoptera, by the differences in nuclear shape and cell distribution in immature spermatocyst. Through the followed spermiogenesis, the spermatocysts were developed into two kinds of mature cyst, a streamline-shaped eupyrene cyst with nucleated sperms of thready head or a long spindle-shaped apyrene cyst with anucleated sperms of cylindrical head. As the results off chromosomal analysis at metaphase of the spermatogonial mitosis and spermatocytic meiosis, the chromosome number were 2n=6a/n=31, respectively, and no variation between individuals.

• Korean Journal of Head & Neck Oncology
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• v.33 no.2
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• pp.59-62
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• 2017

Solitary fibrous tumor (SFT) is an uncommon spindle cell neoplasm that is usually presented as a pleural origin localized tumor. There are few cases, found in thyroid. Twenty six cases found in thyroid have been reported since 1993, and two of these were malignant. We report another malignant case in this study; a 55 years old man visited out-patient clinic due to palpable mass of anterior neck, and pathologically diagnosed as malignant SFT of thyroid after surgical resection. In this study, we focus on the clinical features of this uncommon disease along with other literature reviews.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.2
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• pp.129-138
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• 2012

In this study, three types of large scale multi-tasking machine tools together with core technologies involved have been developed and introduced; a multi-tasking machine tool for large scale marine engine crankshafts, a multi-tasking vertical lathe for windmill parts, and a large scale 5-axis machine tool of gantry type. Several special purpose devices has been necessarily developed for the purpose of handling and machining big and heavy workpieces accurately, such as PTD (Pin Turning Device) with revolving ring spindle for machining eccentric crankshaft pins, hydrostatic rotary table and steady rest for supporting and resting heavy workpieces, and 2-axis automatic swiveling head for high-quality free surface machining. Core technologies have been also developed and adopted on their detail design stage; 1) structural design optimization with FEM structural analysis, 2) theoretical hydrostatic analysis for the PTD and rotary table bearings, 3) box-in-box type cross-rail and octagonal ram design to secure machine rigidity and accuracy, 4) constant spindle rpm control against gravitational torque due to unbalanced workpiece.

• Korean Journal of Head & Neck Oncology
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• v.30 no.1
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• pp.23-27
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• 2014

Low-grade myofibroblastic sarcoma is a rare disorder of malignant soft tissue tumor and is usually occurred various regions that often manifests in the head and neck region. The most common clinical presentation of this entity is non-tender cervical lymphadenopathy. This disease usually presents high possibility of local recurrence and low possibility of distant metastasis. We report a rare case of low-grade myofibroblastic sarcoma occurring in the sternocleidomastoid muscle and invading to the mastoid tip. A 56-year-old male visited the clinic with a complaint of slowly growing postauricular mass for 6 months. Mass originating from sternomastoid muscle and invasion to mastoid tip was observed by imaging studies. Surgical complete excision with simple mastoidectomy was performed via modified facelift approach. The histopathologic findings revealed malignant spindle cell tumor with positive staining with smooth muscle actin. The patient has no recurrence for 2years without any complication.

• Journal of Practical Engineering Education
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• v.14 no.1
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• pp.119-125
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• 2022

Materials used for education are materials such as SM20C, Al6061, and acrylic. SM20C materials are carbon steel and are often used in certification tests and functional competitions, but are also widely used in industrial sites. The Al6061 material is said to be a material that has lower hardness and stronger flexibility than carbon steel, so it is a material that generates a lot of compositional selection of tools. If students are taught practical training using acrylic materials, vibration occurs due to excessive cutting in some parts and damage to the tool occurs. In this process, we examine to what extent the impact on the 2NC head, which is a five-axis equipment, can affect precision control. The weakest part of the five-axis equipment can be said to be the weakest part of the head that controls the AC axis. When the accuracy and cumulative tolerance of this part occur, the accuracy of all products decreases. Therefore, the core part of the 2NC head, the spindle housing, was carried out using an Al7075 T6 (Alcoa, USA) material. In the process of vibration and cutting applied to this material, the analysis was conducted to find out the value applied to the finite element analysis under extreme conditions. It is hoped that this analysis data will help students see and understand the structure of 5-axis machining rather than 5-axis cutting.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.11
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• pp.1187-1192
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• 2013

In the case of 4 wheel drive (4-WD) type car, power switching occurs to 4-WD by operating lever or switch that operates power switching device attached in transfer case which can operate motor by electric signal. So if the RPM of motor is high, power switching will not exactly occur and can cause damage to gear in transfer case according to circumstances. So in this study, we applied 2 level of planet gear type motor spindle of motor drive part of a power train. And conducted decelerating to increase torque to switch power safe and accurately. Also, we researched efficiency of gear by designing reduction gear ratio and gear type and by calculating contact stress and bending strength. Based on researched content, we made drive head of power switching device and a reduction module which uses type that uses motor spindle as sun gear and ring gear as cover.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.10
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• pp.1159-1165
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• 2011

The recording density of HDD is increasing in ratio of 100% each year. Because the increasing of recording density requires the feature of high rotation, fixation and low-noise, fluid hydrodynamic bearing(FDB) has been paid attention to overcome a limitation in ball bearing. Most of researches related to improving performance of FDB have been studied in Japan which has 80% more market share of HDD spindle motor assembly. Main subject of studies are about for the design of the groove shape, manufacturing process of fluid dynamic bearing, performance evaluation and measurement. In HDD, non-repeatable runout(NRRO) is most important parameter which determines the performance of HDD spindle system because NRRO is unpredictable that cannot be compensated in head/slider servo system. In this study, performance evaluation system can measure dynamic behaviors were designed and methodology for calculating imbalance, RRO, and NRRO were proposed.

• Archives of Craniofacial Surgery
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• v.23 no.2
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• pp.77-82
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• 2022

Sarcomatoid squamous cell carcinoma (SSCC), a biphasic malignant tumor consisting of atypical squamous epithelial and mesenchymal elements mixed with epithelioid and spindle cells, is a variant of squamous cell carcinoma. Cutaneous SSCC is very rare and aggressive and has a poor prognosis. Here, we report a case of cutaneous SSCC with satellites and in-transit metastases. A 79-year-old woman presented with a protruding mass on the left temporal area sized 1.2×1.0 cm. The punch biopsy report indicated keratoacanthoma or well-differentiated squamous cell carcinoma. The size of the tumor increased to 2.7×2.0 cm after 8 days. An excisional biopsy was performed with a 2 mm safety margin. The tumor was identified as SSCC with a clear resection margin. Reoperation was performed thrice with an increased safety margin of 10 mm; however, the cancer recurred along with satellites and in-transit metastases. Chemoradiotherapy was administered; however, the size of the tumor increased along with satellites and in-transit metastases. The patient expired 162 days after the initial excision. Complete excision and immediate multidisciplinary approach should be combined during the early stages due to the aggressiveness and poor prognosis of cutaneous SSCC with satellites and in-transit metastasis.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.22 no.1
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• pp.56-59
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• 2011

Inflammatory pseudotumor is characterized by the presence of a mass that may mimic malignancy and is composed of spindle cells mixed with variable amounts of extracellular collagen, lymphocytes, and plasma cells It is benign tumor commonly involves lung and orbit and rarely that occurs in the head and neck The cause and pathogenesis of inflammatory pseudotumor still remain controversial. Some bacterial infection or chronic irritation may have prompted some speculation that an initially reactive process can change into an overt neoplastic disease. It tends to affect children and young adults than old ages. We present a case of inflammatory pseudotumor involving the tongue base, in a 73-year-old patient with repeated oral bleeding that aggravated over a few days. Clinical examination showed angiomatous polyp like findings in oropharynx that easy bleeding tendency. CT images showed well defined soft tissue mass with focal enhancement. After surgery, tumor was finally diagnosed inflammatory pseudotumor by histopathologic examinations showed plasma cells and inflammatory cells in variable fibrotic tissues.

• Journal of Veterinary Clinics
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• v.37 no.2
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• pp.109-113
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• 2020

A 5-year-old female lion-head rabbit weighing 2 kg was brought to a local animal hospital with hematuria. Radiography showed a mass in the uterus, which was removed by ovariohysterectomy. Macroscopic examination showed several masses in both uterine horns. These masses, which invaded the deep uterine walls, were firm to the touch, and their cut surfaces were greyish-white in color. Histopathologically, these masses were nonencapsulated and were composed of spindle cells arranged in cellular, large interlacing bundles or streams. The tumor cells had elongate nuclei with prominent nucleoli, granular chromatin and eosinophilic cytoplasm. Moderate anisocytosis and anisokaryosis were observed. Severe and extensive inflammation and necrosis were present within the masses. Immunohistochemically, the neoplastic cells were positive for vimentin, desmin, and α-smooth muscle actin, but negative for cytokeratin. These uterine masses were diagnosed as leiomyosarcoma. To our knowledge, this is the first report of a uterine leiomyosarcoma in the rabbit in Korea.