• 한국연초학회지
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• 제18권1호
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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.

• 대한두경부종양학회지
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• 제33권2호
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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.

• 한국정밀공학회지
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• 제29권2호
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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.

• 대한두경부종양학회지
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• 제30권1호
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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.

• 실천공학교육논문지
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• 제14권1호
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• pp.119-125
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• 2022

교육용으로 사용되는 피삭재(소재)는 SM20C, Al6061, 아크릴 등의 소재를 사용한다. SM20C 소재는 탄소강으로서 자격증 시험 및 기능경기대회에서 많이 사용되지만 산업현장에서도 많이 사용된다. Al6061 소재는 탄소강에 비하여 경도가 낮아지고 전성(연성)이 강한 소재이기에 공구의 구성인선이 많이 발생하는 소재라고 한다. 아크릴 소재를 이용하여 학생들에게 실습지도 하면 어느 부분에서 과다 절삭으로 인하여 진동이 발생하고 공구의 파손이 발생하는 소재이다. 이러한 과정에서 5축장비인 2NC헤드에게 가해지는 충격이 정밀도 제어에는 어느정도 영향을 줄 수 있는지 알아본다. 5축장비의 가장 취약한 부분은 AC축을 제어하는 헤드가 가장 약한 부분이라 할 수 있다. 이 부분의 정밀도 및 누적 공차가 발생할 경우 모든 제품의 정밀도가 떨어지는 현상이 발생한다. 따라서 2NC헤드의 핵심적인 부분, 스핀들 하우징은 Al7075 T6(미국 알코아사) 소재를 사용하여 진행하였다. 이 소재에서 작용되는 진동 및 절삭 과정에서 힘을 극한조건에서 유한요소 해석으로 적용되는 값을 밝혀 내고자 해석을 진행하였다. 이러한 해석 데이터를 활용하여 학생들이 5축절삭 보다 5축가공기의 구조를 보고 이해하는데 도움이 되기를 기대한다.

• 한국정밀공학회지
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• 제30권11호
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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.

• 한국정밀공학회지
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• 제28권10호
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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.

• 대한두개안면성형외과학회지
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• 제23권2호
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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.

• 대한후두음성언어의학회지
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• 제22권1호
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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.

• 한국임상수의학회지
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• 제37권2호
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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.