• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.56-56
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• 2003

BaTiO$_3$, SrTiO$_3$단일막과 BaTiO$_3$ (BTO)/SrTiO$_3$ (STO) 산화물 인공격자를 pulsed laser deposition (PLD) 법에 의해서 100 nm 두께의 (La,Sr)CoO3 (LSCO) 산화물 전극이 코핑된 MgO 단결정 기판 위에 증착시켰다. 이러한 기판위에서 2 unit cell의 적층 두께를 갖는 BTO/STO 초격자 (=BTO2/STO2)를 100～5 nm까지 변화시켰다. 또한 BTO와 STO 단일막도 같은 두께로 변화시켰다. 이러한 두께 범위에서 BTO, STO 단일막과 초격자의 격자변형에 따른 유전특성을 살펴 보았다. 두께 변화에 따른 단일막과 초격자의 구조 분석은 포항 방사광 가속기의 x-ray 회절에 의해서 이루어졌다. 다양한 두께를 갖는 BTO2/STO2 초격자에서 BTO와 STO 충은 in-plane 방향으로 격자정합을 유지하면서 변형되었다. 두께가 얇아지면서 하부 LSCO영향으로 BTO, STO의 n-plane 격자상수는 LSCO 격자상수 쪽으로 접근하였다. Out-of-plane 방향의 BTO 격자상수는 두께가 얇아지면서 증가하였고 반면에 STO 격자상수는 감소하였다. STO와 BTO 단일막의 격자변형은 두께가 얇아지면서 in-plane 방향으로 압축응력으로 인해 증가하였다. 그러나, 격자부정합도가 큰 BTO격자에서 더 많이 변형되었다. 또한 초격자에서 BTO격자가 BTO 단일막보다 더 많이 변형되었는데 초격자에서는 BTO, STO 두 층의 발달된 변형뿐만 아니라 하부 LSCO/MgO 기판의 영향을 함께 받고 있기 때문이다. 초격자와 단일막의 유전상수를 살펴보면은 두께가 감소하면서 유전상수가 감소하는 size effect을 보이고 있다. 하지만 초격자에서의 유전상수가 단일막보다 우수한 유전특성을 보이고 있다. 이러한 결과로 볼 때 격자변형이 size effect 영향을 끼치는 중요한 요소임을 확인하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.55-55
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• 2003

Ferroelectric 물질은 고유전성, 자발분극과 전기장에 따른 유전상수의 변화 등의 특성을 가지고 있으므로 많은 연구가 진행중이다. 이러한 ferroelectric 물질의 유전 특성에 미치는 요소로는 물질의 조성비, 박막의 스트레스, 결정성 등이 있다. 특히 스트레스에 대한 연구가 활발히 진행중이다. 본 연구에서 산화물 인공격자를 이용하여 단일박막에서 얻을 수 없는 격자변형도를 얻어 격자 변형이 박막의 유전특성에 미치는 영향을 연구하였다. BaTiO$_3$ (BTO)/SrTiO$_3$ (STO) 산화물 인공격자를 Pulsed laser deposition (PLD)법으로 (La,Sr)CoO$_3$ 전극이 코팅된 MGO (100) 단결정 기판위에 증착시켰다. 적층 주기에 변화를 주어 BTO와 STO 각각 1.01~1.095와 0.925 ~ 1.003의 단일 막에서는 얻을 수 없는 격자 변형도를 얻었다. 이 실험적 데이터를 기초로 하여 density functional theory (DFT)라고 불리는 범함수밀도론를 기초한 제일원리적 계산 방법을 통하여 격자 변형된 SrTiO$_3$의 구조적, 전기적 특성을 계산하였다. SrTiO$_3$와 BaTiO$_3$ 격자의 안정성을 분석하기 위하여 Vienna Ab-intio Simulation Package (VASP) code가 사용되었다. SrTiO$_3$와 BaTiO$_3$ 산화물 격자의 안정성 분석 후, frozen-phonon 계산 방법을 사용하여 zone-centered optical phonon mode가 계산되었으며, mode effective charge는 Berry-phase polarization 으로부터 얻어졌다. SrTiO$_3$ 격자가 격자변형이 일어나지 않은 상태로부터 c/a= 0.985로 격자 변형 이 일어남에 따라 optical phonon mode는 점차 hardening되었다. BaTiO$_3$ 격자의 경우 SrTiO$_3$ 격자와는 달리 격자 변형이 1.01~1.023으로 진행됨에 따라 optical phonon mode의 증가를 가져왔으나 Born effective charge의 증가하였으며, 더 이상 격자 변형이 진행됨에 따라 optical phonon mode의 감소를 가져왔으나 Born effective charge의 증가 유전상수는 증가했다. 격자 변형이 SrTiO$_3$ 와 BaTiO$_3$ 산화물 격자의 optical phonon mode와 Born effective charge에 크게 영향을 미쳤다.

• Clinics in Shoulder and Elbow
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• v.7 no.1
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• pp.23-29
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• 2004

It has been reported that rotator cuff tear have good response to arthroscopic or open repair even if the range being so wide. However, the majority of this literature regarding the diagnosis and treatment of tear focused on lesion of the supraspinatus and infraspinatus tendons. But involvement of the subscapularis tendon with rotator cuff tear should be thought to be less common and poorer to open operative repair. Furthermore, some europian author have stated that the rotator cuff tear including the subscapularis tendon are sufficiently distinct in their clinical presentation and prognosis as to merit separate consideration of their diagnosis and treatment. The purpose of this study is to evaluate result of arthroscopic or open repair in patient with rotator cuff tear that include the subscapularis tendon. Of the 128 rotator cuff repairs performed from 1998 through 2003, 12 had a tear that include the subscapularis tendon in combination with the supraspinatus (8 cases) and infraspinatus (4 cases). Mean duration of symptoms before surgical treatment was 6 months (range 3 to 12 months). All 12 patient demonstrated a positive lift off sign. Shoulder function was assessed using the Constant- Murley score, which ranges from 30 to 58. Pain was assessed using a linear visual analogue scale range from 0 to 10. Postoperative Constant score range from 40 to 64 (average 47.8). Pain score improved from 5.5 to 8.5, but there are postoperative pain improvement on nothing in 5 patient. The overall result for 12 patient were satisfy in 2, fair in 5 and dissatisfy in 5: Therefore satisfactory result were noted only in 16 % of this overall group. In conclusion, we have failed to make good result in patient with rotator cuff tear that included the subscapularis tendon. At the result, outcome after surgical repair of this type of rotator tear is comparatively inferior to the result of operative repair of rotator cuff not involved the subscapularis tendon.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2264-2270
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• 2006

This paper describes fast-hewing frequency synthesizers for multi-band OFDM(MB-OFDM) ultra-wide band(UWB) systems. Three different structures in generating 3 center frequencies(3432MHz, 3960MHz, 4488MHz) are designed and compared. The first structure generates 3 center frequencies using only one PLL operating at 4224MHz, and the second uses three PLLs operating at corresponding center frequencies. The proposed third structure employes two PLLs operating at 3960MHz and 528MHz. Simulation results using 0.18um RF CMOS process parameters show that the third structure exhibits boner characteristics in spur, area and current consumption than the other structures. The band switching time of the proposed synthesizer is less than 1.In and the spur is less than -36dBc. The synthesizer consumes 22mA from a 1.8V supply.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.4
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• pp.303-309
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• 2008

The reduction of risk within the workplace has long been focus of attention both through industry initiatives and legislation. Exposure matrices according to industries and processes treated DMF (N,N-Dimethylformamide) were constructed based on KOSHA (Korean Occupational Safety and Health Agency)'s 2005 exposure database which were gathered from Korean agencies of workplace hazards evaluation for business place. These exposure matrices were assessed by danger value (DV) that was calculated from combination of hazard rating, duration of use rating, and risk probability rating of exposure to chemical hazardous agents in accordance with Hallmark Risk Assessment Tool. The results of risk assessment is divided four kinds of control bands which were related with control measures. The applicability of risk assessment using exposure matrices was performed by field study and survey for high matrices group. This study found that more attentions should be paid to two industries, manufacture of sewn wearing apparel and manufacture of textiles, among 19 industries, and to 3 processes, coating, processing & mixing, and lab, among 80 processes because those were regarded as having the highest risk.

• Journal of Chest Surgery
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• v.31 no.3
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• pp.329-335
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• 1998

A 55-year-old male was admitted to our hospital complaining of chest discomfort, dysphagia and severe pain on swallowing. Esophageal manometry showed that there was no relaxation of lower esophageal sphincter to swallowing. There was double barrelled esophagus or mucosal stripe appearance on esophagogram. Endoscopy revealed an appearance as if an esophago-tracheal fistula had been made at the level of the upper thoracic esophagus. Also, two slit-like mucosal tears was seen on the lower esophagus. There after, fasting and total parenteral nutrition for several weeks failed to bring about any changes in his symptoms. So, as treatment, primary closure of the upper opening of the false lummen was performed under general anesthesia. Soon after the surgical procedure, the patient's symptoms were improved except for mild dysphagia. He was discharged after oral intake had been juduciously commenced with fluids and soft diet subsequently. During follow-up in out-patient department, he had no specific symptoms including fever or dysphagia and massive dissection of the esophagus was improved on esophagogram. We report the experience of a case of spontaneous submucosal dissection of the esophagus which required conservative and surgical management

• Journal of Chest Surgery
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• v.30 no.3
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• pp.348-348
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• 1997

A 48 year old man, has been suffering from a growing chondrosarcoma of sternum which has deeply invading the anterior mediastinum: He underwent wide resection of the chest wall tumor including a 4 cm free margin of normal tissue on all portions. The tumor as 15 × 16× 10cm in size arising from sternum and include both proximal one third of the clavicle and the 1 st, 2nd, and 3rd coital cartilages. The resected skeletal defect in the anterior wall was very large after wide resection of the'tumor and reconstructed due to paradoxical chest wall movement with sandwich like method of double over lapping Marlex mesh and methylmethacreylate, and steel wires. The soft tissue reconstructive procedure was dont with myocutaneous flap transposition use of pectoralis muscle. But the patient go infected with tuberculosis in the mediastinum two months after the operation. We had removed all of previously inserted prosthetics and performed curettage and drainage. Recently we experienced a case with giant chondrosarcoma of the sternum associated with tuberculous mediastinitis. The patient had an uneventful postoperative course and was discharged with adjuvant treatment such as antituberculous medication for 1 year.

• Journal of Chest Surgery
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• v.30 no.3
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• pp.248-252
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• 1997

A 48 year old man, has been suffering from a growing chondrosarcoma of sternum which has deeply invading the anterior mediastinum: He underwent wide resection of the chest wall tumor including a 4 cm free margin of normal tissue on all portions. The tumor as 15 $\times$ 16$\times$ 10cm in size arising from sternum and include both proximal one third of the clavicle and the 1 st, 2nd, and 3rd coital cartilages. The resected skeletal defect in the anterior wall was very large after wide resection of the'tumor and reconstructed due to paradoxical chest wall movement with sandwich like method of double over lapping Marlex mesh and methylmethacreylate, and steel wires. The soft tissue reconstructive procedure was dont with myocutaneous flap transposition use of pectoralis muscle. But the patient go infected with tuberculosis in the mediastinum two months after the operation. We had removed all of previously inserted prosthetics and performed curettage and drainage. Recently we experienced a case with giant chondrosarcoma of the sternum associated with tuberculous mediastinitis. The patient had an uneventful postoperative course and was discharged with adjuvant treatment such as antituberculous medication for 1 year.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.45 no.4
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• pp.223-233
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• 2009

It has been considered that fishing areas for shrimp beam trawl have been in ruin because Korean local governments have permitted trawling into the areas limited by the fisheries local regulations from 1994. Physical and biological effects of the trawling were investigated in the study. Physical effects were investigated by optical methods such as trawling tracking by side scan sonar and comparing the gear both before and after trawling. Biological aspects were investigated by grab sampling of benthic animals, concentration of trace metals in sediment and a flux evaluation of ${NH_4}^+,\;{PO_4}^-,\;and\;SiO_2$ by coring. The fishing activity had physical impacts on the seabed but these recovered naturally in less than fourty days naturally, which increased the benthic biodiversity, increases the trace metal concentration of and nutrient flux into the seawater, especially phosphate and silicate. This method and these results can help in further studies looking for disturbances by fishing.

• Applied Biological Chemistry
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• v.41 no.1
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• pp.99-103
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• 1998

Triazolopyrimidine sulfonanilide (TP) derivative is one of excellent herbicide compounds. We have synthesized three classes of a new sulfonamide derivative (TPP) as Acetolactate synthase (ALS) inhibitors, in which the benzene ring in TP skeleton was converted to substituted pyrimidyl ring and examined their inhibitory activities on barley for ALS. $I_{50}$ values of the inhibitors ranged from 0.005 to 2 mM. Comparing the $I_{50}$ value of each class of TPP derivatives, the substituents in pyrimidine and triazolopyrimidine ring were found to affect the degree of ALS inhibition. TPP with substituted methyl group in pyrimidine ring showed higher inhibitory activity than that with methoxy group, while the substitution of the cyclopentano group in triazolopyrimidine ring gave very large inhibitory activity than that of methyl group. The present study established that variation of the electron density by substitution at heterocyclic ring is a very important factor for ALS inhibition, but showed no dependence on steric effect by substituents.