熱處理에 의한 電力 케이블 接續 界面의 絶綠 特性 變化

이창종 한국교원대학교 1998 국내석사

중국 항공우주력 발전과 한국 항공우주력 증강 방안

이창종 국방대학교 국방관리대학원 2014 국내석사

샌드위치 패널구조 물류창고 화재의 연기와 유독가스의 유동특성 및 피난시간 분석

이창종 충북대학교 2022 국내석사

본 연구에서는 물류창고의 사고사례를 통한 위험성을 나타내고 이를 통하여 샌드위치 패널 구조의 물류창고에서 연기 유동성과 유독가스의 위험성을 분석하였다. 이에 물류창고에서 화재가 발생할 경우를 가정하였고, 물류창고의 특성을 입력하기 위하여 화재 시뮬레이션과 피난 시뮬레이션을 활용하였다. 특히 샌드위치 패널의 심재로 우레탄폼, 스티로폼 등을 주로 사용하는데 여기서 발생되는 연기와 유독가스의 유동특성을 분석하였다. 기존에 샌드위치 패널로 지어진 물류창고에 대한 위험성을 도출하고 가연성 물질의 심재를 사용한 샌드위치 패널 구조의 물류창고에 대한 안전관리방안의 필요성을 제시하였다. 구체적인 결과는 다음과 같다. 사고사례에서 물류창고에는 다량의 물건이 적재되어 있고 구조적으로 화재에 취약하며 불이 붙으면 유독가스가 발생하는 우레탄폼, 스티로폼을 재료로 한 샌드위치 패널을 사용하고 있다. 이로 인해 화재 발생 시 폭발적인 연소와 다량의 유독가스가 발생하며 이는 곧 산소결핍과 질식으로 이어져 많은 인명피해가 초래되고 있다. 특히, 2020년 4월 경기도 이천 이어 7월 경기도 용인에서 물류창고 화재가 발생하였다. 2021년 6월 이천에 있는 물류창고에서 화재가 발생하였으며 "대응 단계"를 발령할 정도로 규모가 큰 창고 화재가 연이어 발생하고 있다. 화재 시뮬레이션을 위하여 물류창고 밀집 지역인 경기도 용인시 소재의 “O”사의 냉장·냉동창고를 선정하였으며 평면도와 비상대피도면, 재실자의 분포에 맞춰 시나리오를 설계하였다. 연기와 유독가스의 유동특성을 분석하기 위하여 화재시뮬레이션이 가능한 FDS를 이용하였다. 분석결과 일반 건축물과 다르게 빠른 속도로 급격하게 확산되었다. 연기의 확산속도는 일반 건축물에 비해 급격하게 확산되는 형태가 나타났다. 따라서 가연성 물질인 우레탄폼의 샌드위치 패널로 구성된 물류창고에 대해서는 일반 건축물과 별도로 안전관리방안의 새로운 규정이 필요하다. 피난 시뮬레이션은 화재 시뮬레이션의 연기 유동성과 유독가스의 확산속도를 피난시간과 비교 분석하였다. 일반 건축물의 연기 유동성과 비교했을 때 샌드위치 패널의 연기의 유동성이 빠르게 나타났다. 따라서 우레탄폼의 연소 시 발생하는 유독가스의 위험성을 나타내고 구체적인 피난 대책의 필요성을 제시하였다. 최종적으로 본 연구는 샌드위치 패널 심재 중 주로 이용되었던 우레탄폼의 위험성을 고찰하고 화재 발생 시 인명피해에 직접적 영향을 미치는 유독가스의 확산 특성을 분석하였다. 본 데이터는 물류창고의 안전관리방안을 마련하기 위한 기초자료로 활용이 가능하다. This thesis is aimed to explain the risks (a fire) based on actual accidents that took place at a logistics center and to analyze the dispersion movements of smoke and the harmful effects of poisonous gas at such a place made of sandwich panels. To that end, a fire was assumed to break out at a logistics center and fire and evacuation simulations were utilized to identify the characteristics of such warehousing facilities. Especially, as the cores of sandwich panels are mostly made of urethane foam or styrofoam, the movements of smoke generated from the burning materials and poisonous gas created by their combustion were analyzed. This thesis identified risks entailed in the existing logistics centers built with such panels and proposed the need for safety management plans for such facilities as they are made of combustible materials. Here are the detailed results. In an actual case this thesis focused on, a fire took place at a logistics center that had a substantial amount of merchandise stacked up and was made of sandwich panels made of urethane foam and styrofoam, both of which generate poisonous gas when they catch fire as they are structurally susceptible a fire. As a result, when a fire breaks out at a place like this, this leads to explosive combustion and a large amount of poisonous gas, which translates into a lot of causalities due to lack of oxygen and subsequent asphyxiation. Especially, after an accident in Icheon, Gyeonggi Province, in April, 2020, another fire broke out at a logistics center in July in Yongin, Gyeonggi Province. In addition to them, there was a fire at a logistics center in Icheon, Gyeonggi Province, in June, 2021, signaling that there have been a series of large-scale fires enough to be categorized as the emergency "response phase" at such facilities. For a fire simulation, this thesis chose a logistics center for cold and frozen products of the company "O" in Yongin, Gyeonggi, where many of such centers were located, and designed a scenario reflecting the floor plan, the emergency evacuation plan, and the distribution of occupants. FDS capable of fire simulations was utilized to analyze the heat emissivity generated at the cooler and freezer warehouse and the movements of smoke. The diffusion speed of smoke appeared to spread rapidly compared to general buildings. Therefore, it is deemed necessary to newly establish additional regulations for logistics centers built with sandwich panels made of the combustible urethane foam, separate from those for general buildings. In an evacuation simulation, the movements of smoke and its dispersion speed generated from the fire simulation were compared with the evacuation time for further analysis. Smoke dispersion in a center of sandwich panels was faster than in a general building. Therefore, this thesis suggested the need to let known the hazardousness of toxic gas created when urethane foam is being burnt and to establish detailed evacuation plans. Lastly, this thesis delved into the harmful effects of urethane foam, the major material used to make the cores of sandwich panels, and analyzed the dispersion characteristics of toxic gas that has a direct impact on the scale of casualties. This data may be used as fundamental basis to create safety management plans for logistics center.

쇠고기 수급분석과 개선에 관한 연구

이창종 건국대학교 대학원 축산경영학과 1984 국내석사

용기와 재질에 따른 버섯의 MAP 저장기술

이창종 안동대학교 2010 국내석사

The study was conducted to evaluate the effects of postharvest treatment and modified atmosphere packaging methods on extending simulated shipment and shelf life environment of mushrooms (oyster mushroom, golden mushroom, king oyster mushroom, button mushroom). 1. Oyster mushroom Short-term heat treatment seemed not to greatly affect the quality of the oyster mushrooms. Oyster mushroom was packaged in PS (polystyrene), PP (polypropylene), PET1 (polyethyleneterephthalate) container. PET1 container packaged mushrooms maintained good appearance and marketability. However, PET1 container resulted in high off-flavor. Second experiment was carried out to alleviate the incidence of off-flavor through pin hole treatment on the PET1 container. Results showed that Φ 0.59 mm pin hole treatment successfully reduced off-flavor. However, increased pin hole number increased the rate of decay due to high O2 and low CO2 concentration in the PET1 container. During storage change of off-flavor level was not higher than after shelf life change of off-flavor level. So, during the storage period not treatment a pin hole. Pin hole treatment on the PET1 container only during shelf life. The result of the experiment was that pin hole treatments maintained the oyster mushroom quality during the 7-day simulated shelf life environment. Overall data suggests that optimum precooling temperature should be 0℃ for oyster mushrooms. Packaging of precooled oyster mushrooms packaging PET1 container seemed to provide adequate MAP environment during the shipment. After storage period, PET1 container treatment Φ 0.59 mm or 0.45 mm pin hole. Maximum storage period of oyster mushrooms appeared to be 4 weeks at 0.5±0.5℃ and 7 days on the shelf at 7.0℃±0.5℃. 2. Golden mushroom Changes in quality of golden mushrooms was investigated during storage and shelf life as influenced by packaging material and packaging method (removal of air vs. vacuum packaging). In the first experiment, 100 g-unit mushrooms were packaged in 30 μm cast polypropylene (CPP) or 20 μm PE film bags. Vacuum packaging tended to improve overall mushroom quality only when initial vacuum status maintained during storage and marketing period. Vacuum packaging retarded elongation of stem and opening of the golden mushroom cap. During the storage period there was an increase in the change of off-flavor level for the vacuum packaging during the shelf-life period, while no significant change of off-flavor level differences were observed between vacuum and non-vacuum packaging. The secondary experiment was carried out to evaluate effects of postharvest precooling temperature and packaging method. Results were similar to those of first experiment. The initial vacuum level seemed to be an important factor for golden mushroom quality maintenance. In order to extend the golden mushroom shelf-life period, the initial mushroom temperature should be down 8.0℃ and then, packaged in CPP vacuum packaging. Maximum storage period of golden mushrooms appeared to be 6 weeks at 0.5±0.5℃ and 5 or 7 days at 7.0℃±0.5℃. 3. King oyster mushroom Effect of pin hole (Φ 0.59 mm) and needle hole (Φ 0.45 mm) treatment in combination with Korean paper layers inside PET2 container were investigated as related to the quality of king oyster mushrooms during simulated shipment and on the shelf. Precooled mushrooms were packaged in pin hole 0 or 1 ea PET2 containers; with or without Korean paper. Pin hole (Φ 0.59 mm) and traditional Korean paper treatment affected no significant increase in the appearance of the mushrooms for marketability rating during the 4-week storage and 7-day marketing period. The investigation showed marketability level as higher than acceptable level. However, ethanol accumulation and change of flavor was observed in mushrooms packaged in 0 pin hole PET2 container. For reducing the ethanol level and change of flavor, internal packaging pin hole treatment is necessary. In the second experiment, effects of MAP material and traditional Korean paper treatment on the quality changes of king oyster mushroom were investigated during simulated period of 6-week shipment and 7-day shelf life. Mushrooms were packaged in PET2 container + needle hole (Φ 0.45 mm) 1, 30 μm PE blue film and MP 20 film. Precooled mushrooms were packaged in each MAP material and with or without traditional Korean paper. Change of hole size showed that CO2 concentration was higher with needle hole than that from Φ 0.59 mm pin hole treatment. Korean paper treatment in PET2 container caused overall quality deterioration. For the alternative PET2 container, using 30 μm PE blue film bag, the quality attributes and overall marketability were maintained at the acceptable level. In contrast, MP 20 film produced change of off-flavor development. Maximum storage period of king oyster mushroom appeared to be 6 weeks in storage with a 7-day shelf life in the PET2 container (NH 1+Korean paper 2) or 30 μm PE blue film at low temperature 7℃. 4. Button mushroom Effect of short-term heat treatment, pin-hole treatment, and packaging materials on the button mushroom were estimated. Pin hole treatment on the PET2 container was performed as continuous one hole treatment throughout shipping and marketing process or as two holes with an additional pin hole treatment for marketing process. No significant differences in score were observed in internal package gas composition, change of off-flavor, firmness, texture, and marketability. However, browning rating was significantly influenced by the pin hole treatment method. Button mushroom quality maintenance was advanced by the 1 pin hole treatment. Application of MP 10 film showed no improvement of button mushroom maintenance quality. The MP 10 film with PET2 container internal packaging gas composition comparison showed MP film has low O2 concentration and high CO2 concentration. The effects of precooling method and MA material treatment were investigated during a simulated shipment and local marketing process. Mushrooms were packaged in PET2 container (Φ 0.45 mm needle hole) or MP 40 (40,000 cc/m2/24 h) film for 4 weeks of storage, then put on the shelf at 7℃ for 7 days. No significant differences in internal package gas composition, change of off-flavor, firmness, texture and marketability ratings were observed between two precooling methods, whereas quality attributes were significantly influenced by MA materials. Mushrooms packaged in PET2 container maintained their quality. In contrast, mushrooms packaged in MP 40 film did not maintain off-flavor, texture, browning, and marketability.

部下의 成熟度에 따른 效果的인 리더쉽 類型에 關한 硏究

이창종 단국대학교 경영대학원 1997 국내석사

組織體란 두 사람 이상이 모여 共同目標를 達成하고자 하는 有機體이다. 이러한 組織의 目標達成에 貢獻하기 위해서는 組織構成員들의 協同心을 最大한 發揮할 수 있게 하는 效果的인 리더쉽이 必要한 것이다. 더 나아가 組織內에서 리더는 部下들에게 共同目標를 향하여 潛在的인 能力을 發揮할 수 있게 하는 雰圍氣를 助成하여야 하며, 部下들의 士氣昻揚에 關心을 가져야 한다. 그렇기 때문에 리더쉽을 效果的인 經營管理自體와 同一視하는 경향이 있으며, 오늘날 組織內의 리더의 役割에 많은 關心 을 가지고 있다. 그런데 이와 같은 리더쉽에 대하여는 社會科學의 어느 分野보다도 많은 硏究努力이 투입되었음에도 불구하고, 效果的인 리더쉽에 대한 共通된 理論과 確固한 結論은 아직 형성되어 있지 않고, 또 組織에서의 실제 適用도 매우 어려운 것이 사실이다. 그동안의 리더쉽에 대한 硏究는 特性理論(Trait theory )에서 시작하여 行動理論(Behavioral theort ), 狀況理論(Situational theory )에 이르기까지 무수한 리더쉽 理論이 등장했으며 最近의 硏究方向은 唯一한 最善의 리더쉽 理論은 存在하지 않으며 리더쉽은 리더가 그를 둘러싼 모든 狀況과의 適切한 結合을 통해서만 可能하다는 狀況理論(Situational theory )이 주류를 이루고 있다. 이에 本硏究는 허어시(Her sey )와 블랜차아드(Blanchard)의 狀況理論 (Situational theory )을 中心으로 空軍學軍士官候補生의 成熟度와 이들의 敎育을 擔當하고 있는 訓育官들의 리더쉽 類型을 分析하고 이것을 바탕으로 效果的인 리더쉽 類型을 밝히는데 그 目的이 있었다. 本硏究를 위해 韓國航空大學校에 在學중인 空軍學軍士官候補生140명(1년차 : 70명, 2년차 : 70명)과 訓育官要員5명을 調査對象으로 하였다. 또한 허어시(Her sey )와 블랜차아드(Blanchard)가 開發한 「成熟度- 行動類型綜合測定尺度」(Maturity Style Match Rating Form)를 사용하여 空軍學軍士官候補生들의 成熟度를 測定하였으며, 다음으로는 「리더 有效性및 適應性測定表」(Leader Effectiveness and Adaptability Description : LEAD)를 사용하여 訓育官들의 리더쉽 類型을 測定하였다. 資料分析을 통한 주요 硏究結果는 다음과 같다. 1. 空軍學軍士官候補生의 成熟度는 1년차(3학년)와 2년차(4학년)가 差異가 있는 것으로 나타났다. 2. 訓育官의 리더쉽 類型은 1년차(3학년)와 2년차(4학년)를 對象으로 差異가 있는 것으로 나타났다. 3. 空軍學軍士官候補生의 成熟度에 따른 訓育官의 效果的인 리더쉽 類型은 差異가 있는 것으로 나타났다. 結論的으로 空軍學軍士官候補生의 狀況, 즉 成熟水準에 알맞은 리더쉽 類型을 發揮하여 敎育成果를 效率的으로 達成하기 위해서는 空軍學軍士官候補生의 成熟水準把握과 成熟水準의 變化에 따라 融通性있게 適切한 리더쉽을 發揮할 수 있도록 리더쉽 訓練이나 敎育이 持續的으로 이루어질 것을 제언한다. The organization is a organic - body in which more than two men seek to achieve a commom goal In order to contribute to the achievement of this goal of the organization, there needs the effective leadership that is able to make the members of the organization work with the maximum spirit of cooperation. Moreover, the leader in the organization has to creat the spiritual conditions that can make their potential ability bloom in achieving the common goal, have the concerns about the exaltation of their morale For this reason, there is a trend that identifies the leadership with the effective management itself, and today there is rising much interest m the leader's role in the organization. Although there are more studies m the area of leadership than any other area in social science, the common theory and distinct conclusion about the effective theory are not yet established, and it is very difficult indeed to apply them to the management of the organization Until now there is innumerable the ones of leadership in the leadership theories, from Trait theory, Behavioral theory to Situational theory, while major theory, such as Situational theory says that there is no one best leadership theory, and it can be applied only through binding all the surrounding circumstancesT his study aims to analyse the maturity of the Air Force RO.TC (Reserve Officers' Training Corps) students on the basis of Hersey and Blanchard's Situational Theory and suggest the effective leadership model from that The object of this study is a group of 140 Air Force R.OT.C students in Hankuk Aviation University (first grade : 70, second grade: 70) and their 5 instructors And with the 「Maturity Style Match Rating Form」 which Hersey and Blanchard created, the maturity of the students was measured, then with the LEAD (leader effectiveness and adaptability description) questions the leadership model of the instructors From those analyses produced like these results : 1. There are differences in the maturity between the first grade (junior) and the second grade (senior) of the RO.T.C students. 2. There are differences in the leadership model of instructors between the first grade (junior) and the second grade (senior). 3. There are differences among the leadership models of instructor in accordance with the maturity of the students. Conclusively, in order to develop a leadership model proper to RO.T.C students' conditions, i.e, maturity level, and to achieve the instruction goal, this study suggest continuous leadership training and instruction, so that a good leadership may be properly developed in accordance with the understanding of the students' maturity level and with the change of their maturity level.

열처리에 의한 전력 케이블 접속 계면의 절연 특성 변화

이창종 한국교원대학교 1998 국내석사

公共工事 入札·契約制度 改善 方案에 관한 硏究

李暢鍾 충남대학교 2000 국내석사

After the IMF's bailout, the situation of the Korean construction industry does not improve, as the orders for both of public and private construction works do not increase significantly. Moreover, the number of general contractors tends to increase very sharply, since the licensing system for general contractors has changed from a registration system to an approval system, which is much less strict to new entrants into the construction market. As a result, the degree of competition for receiving orders among the general contractors gets higher, leading to forming cartels among them or submitting dumping bids when bidding for construction projects. Based upon the current situation of the construction industry as mentioned above, the purpose of this thesis is three-fold: The first is to re-define the role and implication of the bidding and contract system, which has played the key role in the Korean construction industry since the introduction of the system into the market; The second is to analyze the influence of the change of bidding and contract system on the bidding behavior of general contractors based on a historical review of the system; The third is to propose some remedy measures of the current bidding and contract system based on an analysis of the opportunistic behavior of the general contractors such as cartels and dumping bids. The bidding and contract system for the last fifty years in Korea has constantly changed according to a changing demand in social environment, mainly between the lowest price awarding system and the restricted average price awarding system. The lowest price awarding system, usually employed during the period of economic booms, is the most suitable one to the principle of market competition, which, however, has resulted in dumpings due to severe competition among general contractors. On the contrary, the restricted average price awarding system, usually employed during the period of economic recessions, has prevented the contractors from dumpings. However, the negative effect of the system is the awarding of construction works not by their technology, but by their luck. The current bidding and awarding system, which is based on the price factor only, has been criticized for the bad quality of construction works and the general contractors' neglect of research and development (R&D), as the average awarding rate for public construction works has ranged between sixty-nine and seventy-three percent. With the advent of a new millennium era, the ministry of construction and transportation (MOCT) of the Korean government has declared its intention to improve the domestic practice up to an international standard by publicly announcing Remedy Measures of the Construction Industry in the Era of New Millennium. The basic direction of these remedy measures is to change the focal point of the policy for the construction industry from industry protection to the principle of competition based on market mechanism. In particular, the government has proposed some policy directions in order to improve the current bidding, awarding and contract system and to enhance construction financing. Based on the re-definition of bidding, awarding and contract system and the analysis of its influence on the bidding behavior of the general contractors, six remedy measures are proposed in this thesis, which are as follows: First, the current bidding and contract system should be diversified by types of ordering agencies, which enables the agencies to consider price and technology simultaneously ; Second, as the construction works are various by nature, the standard and procedure of bidding, awarding and contract system should also be diversified by types of construction works; Third, in order to maintain the remedy measures discussed above, the ordering agencies should enhance their ability to implement the system in practice; Fourth, the government should change the current ordering system for public construction works from centrally concentrated one to decentralized one; Fifth, the government should also adopt a proposal bidding system, in which general contractors propose their own bids according to a basic drawing initially presented by ordering agencies; Sixth, the current qualification system is designed for competition based on price factor only, but needs to be re-designed for competition based on both of price and technological factors.

非破壞檢査法에 따른 콘크리트 部材의 初期材齡狀態에 關한 實驗的硏究

이창종 한밭대학교 대학원 2018 국내석사

비파괴검사법은 기존 건축구조물의 노후화와 자연재해로 인한 구조물의 손상정도를 평가할 수 있는 정밀진단이나 유지관리를 위한 정기점검에 대한 관심사가 증가하고 있는 추세에 중요하며 질적 향상이 불가피하고 특히 초기재령에 따른 콘크리트 부재의 상태평가는 더욱 중요하다. 건축구조물의 신속 정확한 진단을 수행하기 위해서는 응력파 기반 비파괴검사기 법의 장점을 이용한 복합 비파괴검사 기술의 개발이 절실하다. 2016년 9월에 발생한 이스라엘 텔아비브의 한 건설 현장에서 신축 중인 주차장 건물의 붕괴로 인한 인명피해는 콘크리트 구조물의 초기재령 압축강도에 대한 평가의 중요성을 반증해 준다. 이 현장은 붕괴되기 2개월 전 7월에도콘크리트 보가 붕괴되는 사고가 있었으나 초기 재령 상태에서의 콘크리트 압축강도 등 상태평가가 정확하게 이루어지 않아 사고를 미연에 방지하지 못한 것은 교훈으로 남는다. 콘크리트 구조물의 상태를 평가할 때, 시공 후 유지관리 시의 진단뿐만 아니라 시공 중의 품질관리를 위한 다양한 기법을 통한 압축강도 추정이 필요하다. 여기에서 대상 건축물에 손상이나 파괴를 주지 않고 건축물의 상태를 파악하기에 적합한 비파괴검사법을 이용한 진단기법이 주요 관심 사이며, 그 적용성 평가 관련한 많은 연구가 진행되고 있다. 본 연구의 목표는 콘크리트 부재의 초기재령 상태를 파악하기 위한 방법으로 비파괴검사법 중 하나인 초음파속도법과 충격반향기법을 적용하여 콘크리트의 압축강도와 콘크리트 기둥부재의 두께를 추정하고자 한다. 콘크리트 부재 실험체는 설계강도 24, 30, 40 MPa을 대상으로 재령 16, 20, 24, 48, 72, 120시간을 기준으로 6개의 재령에 따른 변수를 설정하여 90개의 모의부재를 제작하여 초기재령의 콘크리트 압축강도 추정과 콘크리트 기둥부재 두께 추정에 관한 실험을 실시하였다. 이로부터 도출된 초음파속도와 압축강도의 상관 관계식은 신축공사 현장에서 콘크리트 구조물의 초기재령 압축강도 추정을 할 수 있으며, 아울러 충격반향기법을 이용하여 콘크리트 기둥부재의 품질관리가 가능함을 확인하였다. 이상의 결과로부터 비파괴검사법은 콘크리트 구조물의 품질관리 기법으로서 그 효용성을 확인하였다.

무선망에서의 TCP 성능향상에 관한 연구

이창종 고려대학교 컴퓨터과학기술대학원 2006 국내석사

본 논문은 유선 망에 최적화 된 TCP(Transmission Control Protocol)- Reno, New Reno, SACK TCP 에 대하여 조사하고 무선 망에서 시뮬레이션 하여 TCP의 성능을 분석하고 무선 망에서의 TCP 문제점을 지적하였다. TCP는 Connection-Oriented Protocol 이며 reliable한 data 전송을 위해 Acknowledgment 사용하고 Retransmission Time-Out value(RTO) 계산하며 packet이 loss 되었을 때는 재 전송을 수행한다. 또한 TCP의 congestion control은 TCP의 성능을 좌우하는 핵심적인 알고리즘이다. 유선 망에서 packet이 loss되는 이유는 주로 네트워크의 Congestion 때문이며, Congestion은 네트워크의 bandwidth가 꽉 차서 더 이상 data를 전송할 수 없는 상태를 말한다. 또한 네트워크는 그 사용자 수와 data traffic 정도에 따라 한 송신단이 사용할 수 있는 bandwidth는 계속 변하기 때문에 이를 네트워크의 상태를 계속 감시하면서 data의 전송률을 제어하는 것이 필요하다. TCP에서 네트워크의 Congestion과 관련하여 이런 일련의 과정을 처리하는 부분이 Congestion Control 이며, Slow Start, Congestion Avoidance, Fast retransmission, Fast Recovery 네 개의 알고리즘으로 구성되어 있다. 또한 New Reno와 SACK TCP는 한 RTT 동안 여러 개의 packet이 loss되는 경우 TCP의 성능이 저하되는 것을 보완하기 위해 TCP를 개선한 것이다. 하지만 유선 망에 최적화 된 TCP는 무선 망에서 크게 성능이 떨어진다. 그 이유는 유선 망과 달리 무선 망은 높은 error rate를 가지며, bandwidth가 작기 때문이며 또한 mobile host의 hand-off 과정에서 송,수신단 사이의 연결이 끊어질 수 도 있다. 본 논문에서는 무선 망의 높은 error rate와 TCP의 Congestion Control에 초점을 맞춰 무선 망에서 TCP의 성능을 분석하였다. 그리고 error rate가 유선 망에서와 같이 낮을 때와 error rate가 높을 때, TCP의 Congestion window를 분석해 봄으로써 TCP의 Congestion Control이 무선 망에서 성능 저하의 주 원인임을 확인하였다. 이미 무선 망에서 TCP의 성능을 개선하기 위한 방안들이 많이 제안되고 있다. 앞으로 TCP가 망에서 error 의해 손상되거나 loss된 packet을 Congestion에 의해 loss된 packet과 구별하여 처리하는 본질적인 해결책을 위한 노력이 필요하다고 생각한다. This paper specifies outlines concerns related to the TCP(Transmission Control Protcol) as well as four TCP congestion control algorithms: slow start, congestion avoidance, fast retransmit and fast recovery. Also this paper describe each of TCP Reno, New Reno, SACK TCP. And I use simulations to explore the throughput of each of TCP Reno, New Reno, SACK over wireless link. In particular, I investigate the performance and congestion window trace of TCP when error rate of wireless link increases. These simulations show the problems of TCP congestion control algorithm over wireless links. In this study, I use the NS(Network Simulator) as a simulator. Simulation model is simply composed of three nodes: fixed host, base station, and mobile node which dose not go beyond base station. And wireless lossy link is approximated by a two-state error model.