Pytorch version is 0.4.1.
Can you check this codes have problem in usages?
input_image = np.vstack([image1, image2])
input_image = 
Variable(torch.from_numpy(input_image).cuda())
output = model(input_image)

Here is my whole structure:
In main.py, I  call train fuction train(model, ...)
and In train() take model
model = model.cuda()
model = model.train()
x = Variable(torch.randn(64, 3, 28, 28).cuda())
output = model(x)