Executive SummaryMarks & Spencer is one of the leading retailers founded by Michael Marks in 1884. From 1980’s to late 1990’s, the company, which is known for its high-quality and high-price, continued to grow rapidly focusing on the quality. However, due to globalization, changeable casual trends, and short fashion life cycles, M&S’s system met the challenge. On the other hand, Zara, a company founded in 1963 in Spain, became a new icon in apparel industry with its fast fashion system.What is different between supply chains of Marks & Spencer and Zara?The supply chain of Marks & Spencer is a centralized structure. It means it takes time. For example, products in Hong Kong were sent to warehouses in UK before the shipment to Asia. Unlike M&S, Zara’s supply chain is more flexible and reliable, since its system is decentralized. Zara’s supply chain made the short design-to-store lead time possible. Even though M&S’s quality is better than Zara’s, customer might not recognize the slight differences between those.M&S’s supply chain is a quite classic. They forecast the next season demands in advance, purchase order, product, pack, and distribute. Since they outsource works from fabric supply to packing, making changes increases cost. On the other hand, Zara handles their entire works by themselves except sewing process. This consistent and stable system can make its production cycle time short through its own facilities and internal logistics. Trendy customers always want to wear the unique designed dress. By making the final design to sales cycle time short (22-30days), by providing limited products more frequently, and by replenishing small batches, Zara is able to satisfy customers’ desire. One of Zara’s strategies is the out-of-stock strategy. In the traditional and previous market, stock out has a negative meaning; loss of sales. However, in fast changing fashion world, there are always another ways to satisfy the customers. Moreover, this strategy makes customers buy Zara’s product at least once, since they are not sure the product that they want to purchase might not be there in next time.Why is it so difficult for Marks & Spencer to play the “Fashion Game”?First of all, M&S cannot follow the trend of apparel industry, due to its low flexibility. M&S usually forecasts demands for next season one year in advance, however, it is too early to change the quantity. When they got they were going wrong, it is too late to pull back. It is not easy to respond fast to the unpredictable fashion market with the traditional centralized supply chain. Moreover, due to the big size of organization, its low flexibility, and its high quantities of inventory, reacting to the changeable market is getting harder. Naturally, it led the company to the drop of M&S’s share price. In addition, narrow customer based products, for instance 5% market share among 15-24 year-old, helped them to lose the market. They failed to deal with short fashion life cycles.At last, in M&S value chain, there were so many outsourced parts such as fabric supply, assembly, packing and so on. If one of these works is delayed, the following works should be delayed. As a result, they cannot help stocking out of trend products.Zara Case Write-Up
. B급 푸쉬풀 회로{대부분의 연산효증폭기 출력은 매우 미약하여 수십mA 정도의 전류를 사용하려 해도 쉽지 않다. 물론 고출력 AMP도 있지만 가격도 비싸도 구입도 쉽지 않을뿐만 않이라 출력도 일정 한계를 갖고 있다. 그래서 등장하는 것이 출력 전류 증강법이다. 출력의 증강은 위그림과 같이 출력에 별도의 드라이브 회로를 부가하는 것이 기본이다.{연산증폭기의 출력을 증강하기위한 회로는 푸시풀 이미터 플러워가 가장 많이 이용된다. 이 회로에서는 연산증폭기 출력의 상하에 다이오드가 붙어 있다. 이 다이오드에는 저항 R3과 R6을 통해서 바이어스 전류가 흐르고 있어서 다이오드 양단전압은 항상 일정한 전압Vf로 되어 있다.NPN 트랜지스터의 베이스는 Vo + Vf 의 전위가 되어 있으며 이미터 플러워에 의해-VBE 전압이 트랜지스터의 이미터 전위가 되지만 실리콘 트랜지스터와 실리콘 다이오드를 사용하면 거의 Vf=VBE 가 되므로 트랜지스터의 이미터전위는 연산증폭기의 출력전압과 동일해진다.아래 쪽 PNP 트랜지스터도 같은 동작을 하며 회로의 출력이 +일때는 위쪽 NPN 트랜지스터가, 출력이 -일때는 아래쪽 PNP트랜지스터가 동작한다. 이와 같이하는 동작을 푸시풀이라고 한다. 저항이나 다이오드 없이 회로를 만들고 싶지만 트랜지스터는 0.6 V정도의 베이스-이미터간 전압이 없으면 동작하지 않기 때문에 충분한 바이어스를 해 다이오드와 저항 R4와 R5가 필요해진다.이 회로의 동작은 반전 증폭기지로서 입출력 관계는 Vout = -Vin * (R2 / R1) 으로 보통 반전증폭기와 같다.보통은 연산증폭기는 크게 잡아야 20 mA 정도의 출력전류 밖에 흘릴 수 없다. 그래서 이러한 출력증강 회로를 사용하는 것이다. 100 mA정도의 출력이 필요하다면 트랜지스터로 2SC1815 - 2SA1015를 사용하고 다이오드는 1S1588 정도면 충분할 것이다. 트랜지스터의 이미터에 들어가 있는 저항은 과전류 보호용 저항으로 트랜지스터가 타 버리는 것을 막기 위해서 넣은 것으로 10 정도면 충분하다.
Zara case write up
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[실험] B급 push-pull 회로
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